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A  [ Alpha ] - [meaning]

• Aback - Condition of sail when the wind pressure is on the leeward or forward side, with sails backed or trimmed to windward (wind on the wrong side of the sails) Also known as "backwinded"
• Abaft - Behind or aft of; on the after side of; towards the stern relative to some other object or position.
• Abaft the beam - Any direction between the beam and the stern, more behind a vessel than in front of it. Behind a perpendicular line extending out from the middle of the boat
• Abeam - At right angles to the the fore and aft line of the boat, or beside, the boat; on the beam; also Abreast.
• Able Bodied Seamen - A member of the deck crew who is able to perform all the duties of an experienced seamen; certificated by examination; must have three years sea service. Also called Able Seamen and A.B.
• Aboard - On or in a vessel. Close aboard is close to another ship or an obstruction
• About - Across the wind in relation to the bow. When a sailboat tacks across the wind to bring it from one side to the other, she is said to go about.
• About Ship - The order to tack the ship
• Above-Board - Above the deck, and therefore open and visible. This gave rise to the term used to denote open and fair dealing.
• Above Deck - On the deck (not over it; see ALOFT).
• Abox - To lay the head-yards abox in a square rigged sailing vessel was to lay them square to the foremast in order to heave-to.
• Abreast - Alongside of; on the beam.
• ABS - American Bureau of Shipping: A U.S. based private classification, or standards setting society for merchant ships and other marine systems.
• Abyss - That part of the ocean lying below 300 fathoms from the surface.
• Access Hole - A hole through casing, bulkhead, floor or deck to enable one to reach work or gear.
• Accommodation - A cabin fitted for the use of passengers.
• A-Cockbill, A-Cockbell - Describing an anchor when it hangs by its ring at the cathead or from the hawsehole ready for letting go.
• Addendum - Additional terms at the end of a charter party.
• Admeasurement - The confirmed or official dimensions of a ship.
• Admiral - The title of a commander of a fleet or a subdivision of it.
• Admiralty Law - The law of the sea; jurisdiction over maritime causes.
• Admiralty Sweep - A large, cautious turn made to approach a gangway or to come alongside a vessel or jetty in a boat.
• Adornings - The gingerbread woodwork on the stern of old sailing ships.
• Adrift - Floating free with the currents and tide; said of a free floating object or boat which can not move by its own power; floating at random.
• Advantage - Method of reeving a tackle in order to gain the maximum increase in power.
• Advection Fog - Can occur any time warm, moist air blows over a surface cool enough to drop it's temperature below the dew point.
• Adventure - Consignments of cargo sent abroad in a ship to be sold or bartered by the master to best advantage or when the opportunity arises.
• Aerodynamic - Having a shape that that is not adversely affected by wind flowing past it.
• Aft - At, near or towards the stern; to move aft is to move back
• After Bow Spring Line - A mooring line fixed to the bow of the boat and leading aft where it is attached to the dock. This prevents the boat from moving forward in its berth. Its opposite, the forward quarter spring line, is used to keep the boat from moving aft in its berth.
• After Hatchway - The hatchway nearest the stern.
• After-leading - Said of a line that leads from its point of attachment towards the stern of the ship.
• Aftercabin - In a ship with multiple cabins, the cabin closest to the stern.
• Aftermast - In a sailing ship carrying multiple masts, the mast set closest to the stern.
• Aftermost - The farthest aft.
• Afterpart - The part of the boat behind the beam.
• Against the Sun - Anti-clockwise circular motion. Left-handed ropes are coiled down in this way.
• Age of the Tide - The interval between full moon and change of moon and the highest high tide.
• Agency Fee - A fee charged to the ship by the ship's agent, representing payment for services while the ship was in port. Sometimes called attendance fee.
• Agent - See Ship's Port Agent
• Agonic Line - Lines on the Earths surface joining point where there is no magnetic variation.
• Aground - When the hull or keel is touching or fast to the bottom of any body of water; on or onto the shore.
• Ahead - In front of the vessel, forward; in a forward direction; opposite of astern.
• Ahoy - Seaman's call to attract attention.
• AHT (Anchor-handling tug) - Moves anchors and tow drilling vessels, lighters and similar.
• Ahull - Lying almost beam on to strong winds and being driven before them while under bare poles (without sails up). The helm is lashed so as to point the vessel into the wind, but it continually falls away because of the pressure of the wind. It is a technique for riding out storms.
• Aid to Navigation (AtoN) - Any fixed object that a navigator may use to find his position, such as permanent land or sea markers, buoys, radiobeacons, and lighthouses, and to indicate safe and unsafe waters.
• Aladdin Cleat - A cleat that attaches to the backstay over the cockpit, usually used for hanging a lantern
• Albatross - Large and long-winged seabird of the southern hemisphere capable of long flights. It was believed among seamen that albatrosses embodied the souls of dead sailors, and it was considered unlucky to kill one.
• Aldis Lamp - A handheld electric lamp with a finger operated shutter used for the sending of signals at sea.
• Alee - Away from the direction of the wind; the side away from the direction of the wind.
• All Aback - With all sails filling from the opposite side from which they are trimmed.
• All Hands - The entire crew; an order on board ship for all seamen to muster on deck immediately.
• All-Around Light - A light showing an unbroken light over an arc of the horizon of 360 degrees. An anchor or riding light is an all-round light.
• All in the Wind - When a sailing vessel is head to the wind and all of her sails are fluttering.
• Allison - The act of striking or collision of a moving vessel against a stationary object.
• Almanac (Nautical) - Annual publication of astronomical data for the use of navigators.
• Aloft - Above the deck, usually overhead on the mast or in the rigging.
• Alongside - Close beside a ship, wharf or jetty.
• Aloof - Old expression meaning to "keep your luff", or sail as close to the wind as possible.
• Alow - Down or downwards; as in "Lay alow!"; opposite of Aloft.
• Altazimuth - Instrument for establishing the altitude and azimuth of stars and planets.
• Altitude - The angle a celestial body makes with the horizon.
• Amain - An old maritime expression meaning "immediately", as "let go amain" (drop the anchor at once!).
• Amas - The outboard hulls of a trimaran.
• Amidships - In or toward the part of a boat or ship midway between the bow and the stern; also midway between port and starboard sides; toward the middle of the ship or boat.
• Ammeter - An instrument for measuring electrical current in amperes.
• Amplitude - (1) In navigation, the angle between the point at which the sun rises and sets and the true east and west points of the horizon. (2) Wave height. *
• Anchor - (1) A heavy metal object, fastened to a chain or line, to hold a vessel in position, partly because of its weight, but chiefly because the designed shape digs into the bottom. (2) The act of using an anchor.
• Anchor Ball - A black ball visible in all directions, displayed in the forward part of a vessel to indicate that the vessel is anchored.
• Anchor Bed - Chocks which hold and anchor in place either in a locker or on deck.
• Anchor Bend - A type of knot used to fasten an anchor to its line.
• Anchor Buoy - A small buoy that is used to mark the position of an anchor. It is attached to the base or crown of an anchor and can be used to recover the anchor if it has to be cast adrift, or to trip it if it becomes wedged.
• Anchor is Apeak - The anchor is under the hawse .
• Anchor is Aweigh - Anchor is off the sea bottom when being heaved in .
• Anchor is Foul - Anchor cable is caught around the fluke or an object is caught around the anchor .
• Anchor Light - A white light, usually on the masthead, visible from all directions, used to indicate that a vessel is anchored.
• Anchor Warp - A hawser or line attached to an anchor.
• Anchor Watch - A member or members of the crew that keep watch and check to see whether the anchor is dragging and the the drift of the ship. This is prudent when anchored in heavy weather, or where wind direction may change dangerously.
• Anchor Windlass - A windlass is a winch-like device used to assist in the raising of the anchor.
• Anchorage - A sheltered place suitable for anchoring in relation to the wind, seas and bottom.
• Anemometer - An instrument for measuring wind speed
• Aneroid Barometer - A mechanical barometer used to measure air pressure for warnings of changing weather.
• Angle of Attack - The angle between the sail and the apparent wind or the rudder or centerline and the water flow.
• Angle of Cut - In navigation, the smaller angle at which two position lines on a chart intersect. The fix will be more reliable as the angle approaches 90°.
• Angle of Heel - The number of degrees of list a vessel has. The first indication that a vessel may need to reef is when there is too great an angle of heel.
• Annual Variation - The amount by which magnetic variation changes up or down each year in a particular area. The annual increase or decrease is printed in the compass roses on each chart and may make a significant difference over a number of years.
• Anode - see Sacrificial Anode
• Anticyclone - Area of high barometric pressure where the wind circulates clockwise in the Northern Hemisphere, and counter-clockwise in the Southern Hemisphere. These are fair weather systems with light or moderate winds.
• Antifouling Paint - A paint applied to the boat's bottom below the waterline which contains "poisons", such as copper, to inhibit the growth of marine life such as weeds or barnacles.
• Anti-Gallicans - A pair of additional backstays temporarily rigged to provide extra support to the masts of square rigged vessels when sailing downwind.
• Apeak - Said of an anchor when the cable is taut and vertical.
• Apostles - Large bollards affixed to the main deck near the bow of a square rigged vessel around which hawsers or anchor cables were belayed.
• Apparent Wind - The direction and speed of the wind as it appears to those on board, relative to the speed and direction of the boat; combination of the true wind and the wind caused by the boat's movement through the water.
• Appendage - A rudder, keel, centerboard, or skeg.
• Apron - A strengthening timber behind the lower part of the stem and above the foremost end of the keel in a wooden vessel.
• Aqualung - A device invented by Captain Jacques Cousteau in 1943 to enable a diver to operate underwater independent from an air supply from the surface.
• Arbitration - Method of settling disputes which is usually binding on parties. A clause usually in a charter party.
• Aries - The point at which the Sun , traveling in the Ecliptic , crosses the Equinoctial when going from South to North declination.
• Armstrong Patent - Slang expression to indicate that a ship was not fitted with any mechanical aids, and that all the work of the ship had to be done with the strong arms of the crew.
• Articles of Agreement - The document containing all particulars relating to the terms of agreement between the Master of the vessel and the crew. Sometimes called ship's articles or shipping articles.
• Articles of War - Disciplinary code in which maritime crimes and punishments are specified.
• Artificial Horizon - An aid to taking as astronomical sight with a sextant when the sea horizon is obscured through haze, fog, or darkness.
• Ashore - On the land or aground.
• Aspect Ratio - The relationship (ratio) between the sails height (luff length) and length along the foot. High aspect ratio means a sail that is tall and narrow, low aspect ratio is a short, squat sail. A high aspect ratio sail is very efficient in sailing close to the wind.
• A-stay - Said of an anchor cable when its line angle approximates a continuation of the fore stay line .
• Astern - Backwards, somewhere behind the vessel, towards the stern; in the direction of, or behind, the stern; opposite of ahead.
• Astrolabe - A precursor to the sextant. An old navigational device for checking the altitude of the sun or stars.
• At Sea - In marine insurance this phrase applies to a ship which is free from its moorings and ready to sail.
• Athwart - Lying along the ship's width, at right angles to the vessels fore-and-aft line (centerline). Same as abeam.
• Athwartship - A member or dimension running from port to starboard.
• Athwartships - From one side of a ship to the other.
• Atoll - A horseshoe-shaped or circular reef of coral surrounding a lagoon.
• A-trip - (1) Said of an anchor immediately when it is broken out of the ground. (2) In square-rigged ships topsails are a-trip when they are fully hoisted and ready for sheeting.
• Auster - Old Latin name for the south wind.
• Autopilot - Electro-mechanical steering device; an instrument designed to control automatically a vessel's steering gear so that she follows a pre-determined track through the water.
• Auxiliary - (1) A second method of propelling a vessel. On a sailboat this would be the engine. (2) Machinery fitted in steam and motor vessels which is not part of the main propelling machinery. (3) a support group, e.g., Coast Guard Auxiliary
• Avast - A command to stop or cease immediately what one is doing.
• Awash - Water washing over; the situation of an object when almost submerged.
• Aweigh - To raise an anchor off the bottom; the position of anchor as it is raised clear of the bottom.
• Awning - A sail or canvas set like a canopy to give shade from the sun .
• Aye - Yes. "Aye aye sir" is a reply on board ship on receipt of an order.
• Azimuth - The bearing of a celestial body from an observer's position.

B  [ Bravo ] - [meaning]

• Baboon Watch -  The unfortunate man who was assigned to remain on deck to watch over the ship's safety while the ship was in harbor, and the rest of the crew were off duty.
• Baby Stay - Secondary forestay supporting the leading edge of the mast and used to flatten the mainsail in building winds.
• Back - The wind shifts in a counterclockwise direction in the northern hemisphere and clockwise in the southern hemisphere (opposite of VEER); the wind is said to back when it changes contrary to its normal pattern.
• Back Splice - [image ] - A splice formed when a crown knot is made in the end of a piece of line and the ends are woven three times or more into the standing part of the line to keep it from unraveling.
• Backing A Sail - To push a sail out so that the wind fills the opposite side, thus slowing the boat down.
• Backing and Filling - Alternatively letting the sails draw, then spilling wind so as to keep a vessel more or less in one place until space is available, marking time.
• Backspring - A spring line from the stern of a boat to mid ships to stop forward movement
• Backstaff - A navigation instrument used to measure the apparent height of a landmark whose actual height is known, such as the top of a lighthouse. From this information, the ship's distance from that landmark can be calculated.
• Backstay - Standing or running (adjustable) wire rigging that supports the mast from the stern; a wire mast support leading aft to the deck or another mast
• Backwind - Wind that is deflected from it's normal course by the sails
• Backwinded - When the wind pushes on the wrong side of the sail, causing it to be pushed away from the wind. If the lines holding the sail in place are not released, the boat could become hard to control and heel excessively.
• Backwinding A Sail - To hold the mainsail or jib off to the side to cause the wind to blow onto the backside of the sail, used to slow a boat
• Baggywrinkle - Tassels of unraveled line, yarns, etc. which are lashed around chafe spots such as spreaders to prevent chafe on sails.
• Bail - To remove water from the boat by hand, bucket, pump etc.
• Bailers - Openings in the bottom or transom of a boat to drain water when sailing.
• Balance - The degree to which all the forces on a boat are symmetrical so the vessel sails with just a slight weather helm.
• Balance Frames - Those frames of a ship's hull which are equal in area, one forward and one aft of the ship's center of gravity.
• Bald-Headed - Sailing term used to indicate a sailing vessel underway with no headsails set.
• Bale - A metal ring on a boom, pole or mast where blocks or shackles may be attached.
• Ballast - Weight at the bottom or the lower portion of the boat to give her stability and/or to provide  satisfactory fore and aft trim.. Ballast can be place inside the hull of the boat or externally in a keel. Heavy substances can be loaded by a vessel to improve stability, trimming, sea-keeping and to increase the immersion at the propeller. Sea water ballast is commonly loaded in most vessels in ballast tanks, positioned in compartments right at the bottom and in some cases on the sides, called wing tanks. On a tanker, ballast is seawater that is taken into the cargo tanks to submerge the vessel to a proper trim.
• Ballast Tanks - Tanks carried in various parts of a ship for water ballast, for stability and to make the ship seaworthy.
• Balloon Jib - A reaching headsail that has a big draft and is usually light-weight 
• Bar - A region of shallow water usually made of sand or mud, usually running parallel to the shore. Bars are caused by wave and current action, and may not be shown on a chart.
• Bar Shot - Iron in a "dumbbell" shape shot into enemy rigging to cut lines and sails. *
• Bar Taut - Said of a rope when it is under such tension that it is practically rigid.
• Barber Hauler - A sail control used to change the athwartships lead of the jib sheet by pulling the sheet toward the centerline of the boat.
• Bare Boat Charter - A charter in which the bare ship is chartered without crew; the charterer, for a stipulated sum taking over the vessel for a stated period of time, with a minimum of restrictions; the charterer appoints the master and the crew and pays all running expenses.
• Bare Poles - Condition of a sailing ship when all sails have been taken down in a severe storm, very often a hazardous undertaking if there is a high sea running.
• Barge - (1) A cargo carrying vessel, usually without an engine, towed or pushed by a tug. Small barges for carrying cargo between ship and shore are known as lighters. (2) Also a term in sail racing - a boat which forces its way illegally between another contestant and the starting line is said to be barging.
• Barnacle - A small shellfish which sticks to the bottoms of ships.
• Barograph - An instrument used to keep a record of atmospheric pressure, such as on a paper drum.
• Barometer - An instrument that measures atmospheric pressure in inches or millibars of mercury
• Barometric Pressure - Atmospheric pressure as measured by a barometer.
• Barque (Also Bark) - A sailing ship with three to five masts, all of them square-rigged except the after mast, which is fore-and-aft rigged.
• Barquentine - Sailing vessel with three or more masts. Square rigged on foremast, fore and aft rigged on all others.
• Barratry - Any wrongful act knowingly done by the master or crew of a vessel to the detriment of the owner of either ship or cargo; and which was done without knowledge or consent of owner or owners.
• Bathyscaphe - A small free-moving submersible designed for exploring the ocean depths.
• Batten - A thin, flexible wooden or plastic strip inserted into a pocket (batten pockets) on the back part (leech) of a sail to stiffen it and assist in keeping its form.
• Batten Down - Secure hatches and loose objects both within the hull and on deck in preparation for approaching bad weather.
• Batten Pockets - Pockets in a sail where battens can be placed to stiffen the sail.
• Battle Honors - The names of battles or individual ship actions in which a warship has taken part, usually displayed in a prominent place on a ship as a source of pride in her name. Known as Battle Stars in the U.S. Navy.
• Bay - An indentation of the coastline between two headlands.
• Beachcomber - Originally a seaman who, not wanting to work, preferred to exist by hanging around ports and harbors and living on the charity of others. Now more generally describing any loafer around the waterfront who prefers not to work.
• Beacon - A lighted or unlighted fixed (non-floating) aid to navigation that serves as a signal or indication for guidance or warning. (Lights and daybeacons both constitute "beacons.")
• Beak - Name given to the metal point or ram fixed on the bows of old war galleys and used to pierce the hulls, and thus sink or disable enemy ships.
• Beam - (1) The transverse measurement of a boat at its widest point. Also called breadth. (2) One of the transverse members of a ship's frames on which the decks are laid.
• Beam Ends - Vessel said to be "on her beam ends" when she is lying over so much that her deck beams are nearly vertical.
• Beam Reach - A point of sail where the boat is sailing at a right angle to the wind (wind coming from abeam). A beam reach is usually the fastest point of sail. A beam reach is a point of sail between a broad reach and a close reach.
• Beam Sea - A situation in which waves strike a boat from the side, causing it to roll unpleasantly.
• Beam Wind - One which blows across a boat's side
• Beamy - Wide, a wide boat is a beamy boat
• Bear, to - The direction of an object from the observer's position.
• Bear Away, Bear Off - To turn the boat away from the wind. Also, Fall Off. The opposite of heading up.
• Bear Down - To approach something from upwind
• Bearing - (1) A compass direction, in compass points or degrees, from one point to another. Relative bearing is the direction relative to the heading of the boat with the bow 0 degrees and the stern 180 degrees. True bearing is the direction from the ship relating to true north with north being 0 degrees and south 180 degrees. (2) Also, a device for supporting a rotating shaft with minimum friction, which may take the form of a metal sleeve (a bushing), a set of ball bearings (a roller ball), or a set of pins around a shaft (a needle bearing).
• Beat / Beating - To sail towards the direction from which the wind blows by making a series of tacks. A point of sail also known as sailing close hauled.
• Beaufort Scale - A number system used to describe wind forces and sea conditions from 0 for a flat calm to 12 for a hurricane
• Becalm - The act of blanketing a ship by cutting off the wind, either by the proximity of the shore or by another ship. A ship motionless by the absence of wind is said to be becalmed.
• Becket - A loop or a small eye in the end of a rope or a block.
• Bee - A ring or hoop of metal.
• Bee Blocks - Wooden swells on each side of the after end of a boom, having sheaves through which to lead the leech reefing pendants.
• Bees of the Bowsprit - Pieces of hard wood bolted to the outer end of a bowsprit through which are rove the foretopmast stays before they are brought in to the bows and secured.
• Before the Mast - Said of a man who goes to sea as a rating compared with officers, and lives forward. Forward of a mast.
• Before the Wind - Sailing with the wind from astern, in the same direction toward which the wind is blowing
• Belay - (1) To make a line secure to a pin, cleat, bollard, bitt, etc. (2) Command to stop or cease action, e.g. "Belay the last order".
• Belaying Pin - Iron or wood pin fitted into racks, around which lines can be belayed or secured.
• Bell - Traditionally a ship's bell is made of brass and has her name engraved on it. It is used for striking the bells which mark the passage of time (see Bells) and is also used as a fog signal as an audible warning of a ship's position.
• Bell Buoy - A navigational buoy on which is mounted a bell with clappers hung inside  a metal cage, which is rung by the motion of the sea. It serves as a warning of shoal waters.
• Bell Rope - A short piece of line spliced into the end of the clapper by which the bell is struck. Traditionally it is finished off with a double wall knot crowned in its end.
• Bells - The strokes on the ship's bell to mark the passage of time. The passage of time in each watch is marked by the bell every half-hour.

Number of Bells	Hour (am or pm)
1	12:30	04:30	08:30
2	01:00	05:00	09:00
3	01:30	05:30	09:30
4	02:00	06:00	10:00
5	02:30	06:30	10:30
6	03:00	07:00	11:00
7	03:30	07:30	11:30
8	04:00	08:00	12:00

C  [ Charlie ] - [meaning]

• Cabin - A room or living compartment for passengers or crew.
• Cabin Sole - The floor or bottom surface of the enclosed space under the deck of a boat
• Cable - (1) A strong rope or chain for pulling or securing anything, usually a ship's anchor. (2) A nautical measurement of distance, a tenth of a nautical mile, 100 fathoms, or approximately 200 yards
• Cable Ship - A specially constructed ship for the laying and repairing of telegraph and telephone cables across channels, seas, lakes, and oceans.
• Caboose - Old term for the galley of a vessel situated normally on the deck and not between decks.
• Cabotage - The carriage of goods or passengers for remuneration taken on at one point and discharged at another point within the territory of the same country.
• Call Sign - A group of letters and numbers used for identification during radio transmission.
• Calm - Little or no wind and flat seas
• Calving - Breaking away of a mass of ice from a glacier or iceberg.
• Cam Cleat - A mechanical cleat used to hold a line automatically. It uses two spring loaded cams that come together to clamp their teeth on the line, which is place between them.
• Camber - The curvature of an object such as a sail, keel or deck. Usually used when referring to an objects aerodynamic or hydrodynamic properties. The weather decks of ships are rounded up or arched in an athwartship direction for the purpose of draining any water that may fall on them to the sides of the ship where it can be led overboard through scuppers; the camber is the crown or arch of a weather deck.
• Camel - Hollow vessel of iron, steel or wood, that is filled with water and sunk under a vessel. When water is pumped out, the buoyancy of the camel lifts the ship. Very valuable aid to salvage operations.
• Can or Can Buoy - A cylindrical navigation buoy painted green and having an odd number used in the United States as a navigational aid. At night they may have a green light.
• Canal - A manmade waterway used to connect bodies of water that do not connect naturally. Canals use locks to raise and lower boats when connecting bodies of water that have different water levels.
• Canoe Stern - A pointed stern, such as those on a canoe.
• Cant - (1) A term signifying an inclination of an object from a perpendicular; to turn anything so that it does not stand perpendicularly or square to an object. (2) Those timbers in a ship near the bow or stern which are sharply angled from the keel. (3) The operation of turning a ship's head one way or another.
• Cant Frames - Angled frames in the extreme forward or aft ends of a ship which form the sharp ends of the vessel's hull.
• Canvas - Tightly woven cloth used for sails, awnings, covers, dodgers and biminis; slang for sails.
• Cap - A piece of trim, usually wood, used to cover and often decorate a portion of the boat, i.e., caprail.
• Capsize - To turn a boat over
• Capstan - A revolving cylindrical device used for heaving in lines or anchors - A vertical, spool-shaped rotating drum around which cable, hawser or chain is wound for hoisting anchors, sails and other heavy weights. A capstan rotates around a vertical axis, as opposed to a windlass, which revolves around a horizontal axis.
• Captain - The person who is in charge of a vessel and legally responsible for it and its occupants.
• Car - A sliding fitting that attaches to a track allowing for the adjustment of blocks or other devices attached to the car.
• Caravel - Small trading vessel also used for exploration. Three-masted, being square-rigged on the two forward masts, and having a lateen rigged mizzen mast. Christopher Colmbus' small squadron, the Santa Maria, Pinta, and Nina, were all Caravels, as were Magellan's ships in his famous circumnavigation.
• Cardinal Points - The compass points of North, East, South and West. Intercardinal or half-cardinal points are Southeast, Southwest, Northwest and Northeast
• Careen - To list a vessel so that a large part of her bottom is above water. This is done to remove weed and marine growth, to examine the bottom, to repair it and to put on preservative or anti-fouling.
• Careenage - A suitable beach, being steep and sandy, where ships could be careened for cleaning or repair.
• Cargo - Ship supplies.
• Cargo Handling - The act of loading and discharging a cargo ship.
• Cargo Hatch - An opening in a ship's deck for the loading and discharging of any kind of cargo.
• Carline or Carling - Timbers used to support the deck planking of a wooden ship; also for supporting hatches.
• Carlins - Structural pieces running fore and aft between the beams.
• Carrack - Old three-masted trading vessel which was square-rigged on the fore and main masts, and lateen rigged on the mizzen mast. Similar to the Caravel, but larger and more robust.
• Carrick Bend - [image] - A knot used to tie two lines together.
• Carriers - Owners or operators of vessels providing transportation to shippers. The term is also used to refer to the vessels.
• Carry On - To continue sailing under the same canvas despite the worsening of the wind.
• Cast Adrift - To abandon a ship at sea; to place people in a ship's boat or raft and leave them.
• Cast Off - To let go of a line; to leave a dock or a mooring; to untie or loose a rope or line.
• Castaway - A shipwrecked sailor as compared with one who has been marooned or deliberately put ashore.
• Cat's Skin - Light, warm wind on surface of sea.
• Catamaran - A multihull with two hulls separated by a deck or crossbeams from which a trampoline is suspended; abbreviated "cat."
• Catboat - A small boat with the mast stepped far forward, carrying a single sail
• Cathead - On older sailing ships, a heavy piece of curved timber projecting from the bow for the purpose of holding anchors in position for letting go or for securing them after weighing.
• Catching Up Rope - Light rope secured to a buoy to hold vessel while stronger moorings are attached.
• Catenary - The curve (sag) of a rope, cable or chain hung between two points such as the anchor rode or towing line; the deeper the curve, the more catenary.
• Catharpings - In square-rigged vessels, short lines at the lower end of the futtock shrouds used to bring in the shrouds tighter to give room to brace the yards at a sharper angle when sailing close hauled.
• Cat-O'-Nine-Tails - Similar to a whip, an instrument of punishment where seamen were flogged on their bare backs.
• Catspaw - (1) A ruffle on the water indicating a breath of wind during a calm (2) A twisting hitch made in the bight of a rope to form two eyes, through which the hook of a tackle is passed for hoisting purposes. [image]
• Catug - Short for Catamaran Tug. A rigid catamaran tug connected to a barge. When joined together, they form and look like a single hull of a ship.
• Catwalk - On a ship, a raised bridge running fore and aft from the midship, and also called "walkway". It affords safe passage over the pipelines and other deck obstructions.
• Caulking/Calking - Forcing material into the seams of the planks in a boat's deck or sides to make them watertight; the material itself. Oakum was once the material used for this purpose, and was then sealed with hot pitch to prevent it from rotting. Today there are polymers used for sealing all kinds of fittings.
• Cavitation - Loss of effective propeller thrust caused by the blades cutting across the column of water sucked along by the propeller instead of working in it. Can also lead to heavy vibration of the vessel.
• Celestial Navigation - To calculate your position using time, the position of celestial bodies, and mathematical tables. Position is determined by measuring the apparent altitude of one of these objects above the horizon using a sextant and recording the times of these sightings with an accurate clock. That information is then used with tables in the Nautical Almanac to determine one's position.
• Celestial Sphere - An imaginary sphere surrounding the globe that contains the sun, moon, stars and planets.
• Center of Buoyancy - A point through which all buoyant forces on an immersed hull are assumed to act.
• Center of Effort (CE) - Point at which all of the force of the wind can be thought to concentrate; the point in the sail plan that is the balance point for all the aerodynamic forces
• Center of Lateral Resistance (CLR) - Center point of all underwater area of the hull where the hull's lateral resistance can be said to be centered.
• Centerboard - A board that can be raised and lowered by pivoting in a watertight box called the trunk or well to increase the draft and lateral area of the hull, preventing the boat from sliding sideways. Unlike a daggerboard, which lifts vertically, a centerboard pivots around a pin, usually located in the forward top corner, and swings up and aft.
• Centerboard Trunk - Watertight housing for the centerboard.
• Centerline - The imaginary line running from bow to stern along the middle of the boat.
• Certificate - A legal paper or license of a boat or its captain.
• Certificate of Registry - A document specifying the nation of registry of the vessel.
• Chafe - Abrasion, wear or damage to a line caused by rubbing against another object
• Chafing Gear - Canvas, cloth, leather, tubing, rubber or other material placed around a line or cable to protect it from wear and abrasion
• Chain Locker - The compartment, near and below the hawse holes at the bow, for stowing the anchor chains; a compartment in the lower part of a ship for stowing an anchor chain.
• Chain Pipe - A pipe of large diameter, through which the chains pass into the chain lockers.
• Chain Plate - A metal plate, strap, or rod bolted to the hull structure to which the lower ends of shrouds and stays are attached
• Chandler - A person who deals in the selling of provisions, dried stores, supplies, equipment, etc.
• Chandlery - A marine hardware store.
• Channel - A navigable route on a waterway, usually marked by buoys. Channels are deep enough for ships or boats to navigate without running aground.
• Channel Fever - Seaman's name for the excitement on board as the ship approachs her destination, giving the crew some liberty ashore.
• Chanty or Shanty - Shanties are the work songs that were used on the square-rigged ships of the Age of Sail. Their rhythms coordinated the efforts of many sailors hauling on lines.
• Characteristic - The distinguishing qualities of a navigational light, including its color and whether it is fixed or flashing (and the flashing sequence).
• Charley Noble - Galley smokestack or chimney.
• Chart - A representation on a plane surface of the spherical surface of the earth. The equivalent of a map for use by navigators.
• Chart Datum - The water level used to record data on a chart. Usually the average low tide water level. It is the level below which depths on a chart are measured, and above which keights of a tide are expressed.
• Chart Table - A table designated as the area in the boat where the navigator will study charts and plot courses.
• Charter - The renting of a boat
• Chearly - An old expression meaning heartily or quickly.
• Check - To ease away slowly, as in a line, sheet, or falls of a tackle.
• Checking - Slacking a rope smartly, carefully and in small amounts.
• Cheek Block - A block with one end permanently attached to a surface.
• Cheeks - (1) The two sides of a block. (2) Pieces of timber attached to the mast below the masthead to support the trestle trees.
• Cheese Down - To coil down the tail of a line on deck to present a neat appearance.
• Chief Engineer - The senior engineer officer responsible for the satisfactory working and upkeep of the main and auxiliary machinery and boiler plant on board ship.
• Chief Mate - The officer in the deck department next in rank to the master; second in command of a ship. He is next to the master, most especially in the navigation and as far as the deck department is concerned. The chief mate assumes the position of the Master in his absence.
• Chinch - The operation of pressing oakum into a seam as a temporary measure until the seam can be properly caulked.
• Chine - The angle of intersection between the topsides and the bottom of a boat. In a hard-chined boat this angle is pronounced.
• Chock - (1) A deck fitting to guide an anchor, mooring, towing or docking line. Usually smooth shaped to reduce chafe. (2) A wedge or block to keep an object from moving.
• Chock-a-Block - When a line is pulled as tight as is can go, as when two blocks are pulled together so that no further movement is possible (also known as "Two blocked").
• Choke the Luff - To temporarily stop all movement of a line through a block by placing the hauling part across the sheave of the block. This jams the sheave and holds it tight, and a pull on the hauling part will release it.
• Chop - Small, steep disorderly waves at rapid intervals.
• Chord - An imaginary line drawn between the luff and leech of a sail. The chord depth is an imaginary line drawn to the deepest part of the sail from the chord. The ratio of chord depth to chord length represents the sail's draft - a high ratio indicates a full sail; a low ratio, a flat sail.
• Chow - Food.
• Chute - An opening in the deck near the bow from which the spinnaker is hoisted. Spinnakers are also often referred to as chutes.
• Ciguatera - A severe type of food poisoning caused by eating contaminated fish
• Circumnavigate - To sail around the world
• Circumnavigation - A voyage around the world.
• Clap On - To clap on is to temporarily add something to an existing part.
• Class - General category into which boats of the same or similar design are grouped for racing.
• Classification Society - Worldwide experienced and reputable societies which undertake to arrange inspections and advise on the hull and machinery of a ship. A private organization that supervises vessels during their construction and afterward, in respect to their seaworthiness, and the placing of vessels in grades or "classes" according to the society's rules for each particular type.
• Claw Off - Beat to windward to avoid being driven onto a lee shore.
• Claw Ring - A "C" shaped fitting which can be slipped over the boom, for example, when the sail has been roller reefed to allow the boom vang to be reattached.
• Clean - Referring to the lines of a vessel's hull when they give a a fine and unobstructed run from bow to stern so that she moves through the water smoothly.
• Clear - (1) Free, not entangled (2) To finalize all formalities in a Customs House.
• Clear for Running - A sheet or halyard coiled so that it will run out quickly without becoming tangled.
• Clear the Decks - Remove unnecessary things from the decks usually in preparation for oncoming bad weather.
• Cleat - A fitting of wood or metal, secured to the deck, mast, or spar, with two horns around which ropes are made fast. The classic cleat to which lines are belayed is approximately anvil-shaped; verb - to belay.
• Clevis Pin - A large pin that secures one fitting to another.
• Clew - The lower aft corner of a fore and aft sail, both lower corners of a spinnaker, and the lower corners of a square sail
• Clew Outhaul - The tackle used to adjust the clew in and out on the boom.
• Clinometer - Instrument showing the angle of heel of a vessel, usually a weighted pointer resembling a pendulum, that swings along an arc that is marked in degrees. *
• Clipper - A sharp-bowed sailing vessel of the mid-19th century, having tall masts and sharp lines; built for great speed; the generic name used to describe types of fast sailing ships.
• Clock Calm - Absolutely calm weather with a perfectly smooth sea.
• Close Aboard - Close alongside; very near; in close proximity to.
• Close Hauled - A point of sail where the boat is sailing as close to the wind (as directly into the wind) as possible; sails are pulled in tight, enabling the boat to point as high as possible to the direction the wind is coming from; Also, "beating" and "on-the-wind".
• Close Reach - Sailing with the wind coming from the direction forward of abeam. A close reach is the point of sail between a beam reach and close hauled.
• Closest Point of Approach (CPA) - The nearest another vessel will come to yours when both are under way, usually expressed in distance and relative bearing.*
• Clothing - Various pieces of rigging which hold a bowsprit in position.
• Clove Hitch - [image] - Two half hitches around a spar or post. Easy way to make a line temporarily fast to a piling or post. The clove hitch can jam under heavy tension, making it difficult to untie. Worse, is its tendency to untie itself when subjected to repeated strain and release, such as a boat rocking in waves. You can add one or two half hitches on the standing line for a more secure attachment.
• Club - A boom on a jib or staysail.
• Coach Roof - The cabin roof, raised above the deck to provide headroom in the cabin. Also trunk.
• Coachwhipping - Decorative ropework with an even number of strands to form a herring-bone pattern.
• Coaming - A low vertical lip or raised section around the edge of a cockpit, hatch, etc. to prevent water on deck from running below.
• Coast Pilots - Books covering information about coastal navigation, including navigational aids, courses, distances, anchorages and harbors.
• Coastal Navigation - Navigating near the coast, allowing one to find one's position by use of landmarks and other references.
• Coastwise - Domestic shipping routes along a single coast.
• Cocked Hat - The small triangular space found at the intersection of lines of position on a chart when a ship's position is determined by taking three bearings.
• Cockpit - The location from which the boat is steered, usually in the middle or at the stern of the boat.
• Cockpit Sole - Floor of the cockpit.
• Cockswain - The steersman of a boat, in direct charge of the crew if any. Pronounced "Cock-sun."*
• Coffee Grinder - A large and powerful sheet winch
• Cofferdam - A void or empty space separating two or more compartments for the purpose of insulation, or to prevent the liquid contents of one compartment from entering another in case of a leak.
• COG - Course Over Ground
• Coil - To lay a line down in circular turns, known as fakes, or to arrange in loops so it can be stowed. Line is sold by the coil, which contain 200 fathoms
• Cold Front - Used in meteorology to describe a mass of cold air moving toward a mass of warm air. Strong winds and rain typically accompany a cold front.
• Cold Molding - A method of bending a material into an appropriate shape without heating or steaming the material first to soften it.
• Colimation - Correct alignment of the optical parts of an instrument.
• Collier - Vessel used for transporting coal.
• Collision Avoidance System - Electronic system commonly used to prevent collisions in inland navigable waterways.
• Collision Bulkhead - A watertight bulkhead at the forepeak extending to main deck. This bulkhead prevents the entire ship from being flooded in case of a collision.
• Collision Mat - A large square of heavy canvas fitted with lines to allow it to be drawn under the hull of a ship where it is damaged. The pressure of the seawater holds it tight against the ship and greatly reduces the inflow of water.
• Colors - National flag or insignia flown by a ship at sea.
• COLREGS - Convention on International Regulations for Preventing Collisions at Sea; Rules of the Road. Internationally accepted rules by which vessels at sea must keep clear of each other.
• Comb the Cat - When flogging a seaman, to run the fingers through the Cat-O'-Nine-Tails after each stroke to separate the strands in preparation for the next stroke.
• Combi - Combination passenger/cargo vessel.
• Combined Ships - Ships which can carry both liquid and dry bulk cargoes.
• Come/Coming About - Bringing the boat from one tack to the other when sailing into the wind, so that the sail is flown in the opposite side by turning through the eye of the wind; Tack
• Come Home - An anchor is said to come home when its flukes are not holding in the ground and it drags.
• Commander - The naval rank next below that of Captain.
• Commission - (1) The documents by which naval officers hold their status as accredited officers in the navy they serve. (2) To place a vessel into active service. Decommission is to remove such a vessel from activity.
• Commodore - (1) An intermediate rank between Captain and Rear Admiral, often held by a senior captain when given extra responsibility. (2) The leader of a yacht club.
• Companion Way - The area leading down from the deck to the cabin, usually with steps (ladder)
• Company - The whole crew of a ship.
• Compartments - The spaces between the transverse bulkheads of a ship.
• Compass - Navigation instrument, either magnetic, containing a magnetized card indicating the direction to magnetic north (showing magnetic north) or gyro (showing true north).
• Compass Card - A card labeling the 360° of the circle and the named directions such as north, south, east and west. Part of a compass, the circular card is graduated in degrees. It is attached to the compass needles and conforms with the magnet meridian-referenced direction system inscribed with direction. The vessel turns, not the card.
• Compass Course - The direction of a ship's heading as read on a compass. The compass course has added the magnetic deviation and the magnetic variation to the true course.
• Compass Error - The amount the compass is deflected from the true direction by variation (magnetic) and deviation (metallic influences) together
• Compass Rose - A circle on a chart, showing all 360°, indicating the direction of geographic north and sometimes also magnetic north.
• Complement - The number of officers and crew employed upon a vessel for its safe navigation and operation.
• Composite Construction - An object made with more than one type of material.
• Compression Post - A vertical post, supporting the coach roof or deck, between a deck-stepped mast and (usually) the keel.
• Con - Station, usually on the bridge, from which a ship is controlled; the act of so controlling.
• Container Ship - A ship constructed in such a way that she can easily stack containers near and on top of each other as well as on deck. The hull is divided into cells that are easily accessible through large hatches, and more containers can be loaded on deck atop the closed hatches.
• Continental Shelf - A region of relatively shallow water surrounding a land mass where the depth increases gradually before it plunges into the deeps of the ocean.
• Contline - The spiral grooves between the strands of rope after it has been laid up.
• Contraband - Goods which have been prohibited from entering a belligerent state by the declaration of a blockade.
• Convoy - One or more merchant ships sailing in company to the same destination under the protection of naval ships.
• Co-ordinates - The definition of the exact position on the surface of the globe in relation to two lines, latitude and longitude, which intersect at right angles.
• Copper Sheathing - Thin sheets of copper applied to the hull of a wooden ship below the waterline to prevent the toredo worm eating the planks, and also to limit the growth of weed, barnacles or other marine life.
• Cordage - Any rope or line.
• Corinthian - A 19th century term for a yachtsman who sails his own yacht without the help of a professional skipper.
• Corsair - A private ship operating under license from a government against the merchant shipping of an enemy.
• Cotter Pin - A small double-pronged bendable pin used to secure a clevis pin or to keep turnbuckles from unwinding.
• Counter - The overhang of the stern aft of the stern post. At the stern of the boat, that portion of the hull emerging from below the water, and extending to the transom.
• Counter Current - That part of the water which is diverted from the main stream of a current and as a result flows in the opposite direction.
• Course - (1) The prescribed compass direction in which a vessel is being steered (2) The lowest yard on a mast (square-rigged vessels). (3) The large square sail that hangs from that yard (4) The sequence of marks rounded in a race
• Course Protractor - An instrument with a movable arm to plot a course on a chart
• Courtesy Flag - A smaller version of the flag of the country being visited. It is flown from the starboard spreader.
• Cove - (1) A small coastal inlet generally protected from the worst of the prevailing winds. (2) A thin, hollowed line cut along a yacht's sheer below deck level and traditionally gilded.
• Cover - In sailboat racing, to have a controlling position over competitors by staying between them and the next mark or buoy - a tactical maneuver in which the lead boat stays between the trailing boat and the wind or the next mark.
• Cow-Hitch - Any bend or hitch which slips as a result of being improperly tied; an improvised knot which is not a recognized maritime knot as used at sea.
• Cowls - Scoop like devices used to direct air into and ventilate a boat.
• Coxswain, Cockswain - The helmsman.
• CQD - The original distress call made by a ship requiring assistance, giving way to SOS.  It stood for CQ, the signal for all stations (still used by Amateur Radio Operators, or Hams), and D for distress; it also meant "Come Quickly, Danger" 
• CQR Anchor - An anchor that is designed to bury itself into the ground by use of its plow shape. Also called a plow anchor.
• Crabbing - Going sideways due to a current's set.
• Crack On - To carry sail to the full limit of strength of masts, yards, and tackles.
• Cradle - A frame that supports a boat when she's hauled out of the water onto shore.
• Craft - Vessel or vessels of practically any size or type.
• Crank - Said of a vessel with little stability, whether due to design or to stowage of cargo.
• Creep - To search for a sunken object by towing a grapnel along bottom.
• Crest - The top of a wave.
• Crew - Personnel, excluding the Master, who serve on board a vessel (also excludes the passengers on passenger ships). In some cases a differentiation between officers and ratings is made; but officers are "crew" in a legal sense.
• Crew List - List prepared by the master of a ship showing the full names, nationality, passport or discharge book number, rank and age of every officer and crew member engaged on board that ship. This serves as one of the essential ship's documents which is always requested to be presented and handed over to the customs and immigration authorities when they board the vessel on arrival.
• Cribbing - Timbers used to support bottom of ship while it is under construction.
• Crimp - Person who decoys a seaman from his ship and gains money by robbing and, or, forcing him on board another vessel in want of men.
• Cringle - A large reinforced eye in the leech and clew of a sail that allows a line to fasten to it; e.g., the reef cringle and clew cringle.
• Cross Bearing - Two or more bearings are noted on the chart in order to determine the ship's position at the intersection of the two
• Cross Bracing - Iron or steel straps fastened diagonally across a ship's frames to make a rigid framework.
• Cross-Jack Yard - The lower yard on a mizzen mast of a square-rigged ship.
• Cross Sea - A sea running in a direction contrary to the wind, which can be confused and dangerous.
• Crossing the Line - A ceremony performed on board ships when passengers or crew are crossing the equator for the first time during a voyage.
• Crosstrees - Small horizontal spars extending athwartships from one or more places along the mast. The shrouds cross the end of these "spreaders", enabling the shrouds to better support the mast.
• Crown - A knot formed by taking the strands of the end of a line and tucking them over and under each other to prevent them from unraveling. 
• Crow's Nest - A platform and protective coaming setting high up on a mast, to accommodate the look-out aloft while the ship is at sea.
• Cruise - Voyage made in varying directions. To sail in various directions for pleasure, in search, or for exercise.
• Cuddy - A small sheltered cabin on a boat.
• Culage - Laying up of a vessel, in a dock, for repairs.
• Cunningham - A line used to control the tension along a sail's luff in order to maintain proper sail shape.
• Current - Horizontal movement of the water caused by tidal change, wind, river movement, or circular currents caused by the motion of the earth.
• Customary Dispatch - Usual and accustomed speed.
• Customs - Government officials responsible for regulating goods, services and supplies into a country.
• Customs Manifest - Document listing all personal goods of crew members.
• Cut - The shape or design of a sail.
• Cut of His Jib - The recognition of a person by his recognizable characteristics (originally, the shape of the nose)
• Cut Splice - Two lines spliced together to form an eye.
• Cutlass - A short, curved sword associated with naval hand-to-hand combat. *
• Cutlass Bearing - The bearing surrounding the propeller shaft where it exits the hull.
• Cutter - A single masted sailboat similar to a sloop except sails are arranged so that many combinations of areas may be obtained. A sail plan with two headsails, a main jib and a smaller staysail set between the jib and the mast.
• Cutting His Painter - A seaman's personal "painter" is his lifeline, and if it is severed, he dies.
• Cutwater - The forward curve of the stem of a ship.

D  [ Delta ] - [meaning]

• Dacron - A synthetic polyester material.
• Daggerboard - Similar to a centerboard, except that it is raised and lowered vertically in a trunk rather than pivoted. Like a keel, daggerboards are used to reduce leeway by preventing a sailboat being pushed sideways by the wind.
• Danforth Anchor - A brand of lightweight anchor. It has pivoting flukes that dig into the ground as tension is placed on the anchor.
• Davit(s) - A small crane that projects over the side of the boat to raise or lower objects (such as smaller boats) from or to the water.
• Davy Jones - Nautical slang for the spirit of the sea, usually in the form of a sea devil. Davy Jones's Locker is the bottom of the sea, the final resting place of sunken ships, articles lost or thrown overboard, and of men buried at sea.
• Daybeacon - A fixed navigation aid structure, visible during the day, used in shallow waters upon which is placed one or more daymarks.
• Daymark - A signboard attached to a daybeacon to convey navigational information presenting one of several standard shapes (square, triangle, rectangle) and colors (red, green, orange, yellow, or black).  Daymarks usually have reflective material indicating the shape.
• Daysailor - A small boat intended to be used only for short sails or racing.
• Dayshape - Black diamond, ball, and cone shapes hoisted on vessels during the day to indicate restricted movement, ability, or type. For example three balls means aground.
• Dead Ahead - A position directly in front of the vessel.
• Dead Astern - A position directly aft or behind the vessel.
• Dead on End - Said of wind when exactly ahead; and of another vessel when her fore and aft line coincides with observer's line of sight.
• Dead Horse - Seaman's term for the period of work on board ship for which he has been paid in advance when signing on.
• Dead Marine - An empty wine bottle after its contents have been drunk.
• Dead Reckoning - The process of plotting a theoretical position or future position based on advancing from a known position using speed, time, and course, without aid of objects on land, of sights, etc. Term comes from deduced reckoning, abbreviated first to "ded reckoning".
• Deadeyes - Circular blocks in the shrouds or stays to adjust tension.
• Deadfreight - Space booked by shipper or charterer on a vessel but not used
• Deadhead - (1) A floating log. (2) A useless member of the crew, a person skylarking.*
• Deadlight - Fixed ports that do not open which are placed in the deck or cabin to admit light.
• Deadrise - The measurement of the angle between the bottom of a boat and its widest beam. A vessel with a 0º deadrise has a flat bottom, high numbers indicate deep V shaped hulls.
• Deadweight - A common measure of ship carrying capacity. The number of tons (2240 lbs.) of cargo, stores and bunkers that a vessel can transport. It is the difference between the number of tons of water a vessel displaces "light" and the number of tons it displaces "when submerged to the 'deep load line'." A vessel's cargo capacity is less than its total deadweight tonnage. The difference in weight between a vessel when it is fully loaded and when it is empty (in general transportation terms, the net) measured by the water it displaces. This is the most common, and useful, measurement for shipping as it measures cargo capacity.
• Deadwood - Heavy longitudinal timbers fastened over the keelson. The timbers of the bow and stern are fastened to the deadwood.
• Deck - A permanent covering over a compartment, hull or any part of a ship serving as a floor.
• Deck Beam - A beam which supports a deck.
• Deck Gang - The officers and seamen comprising the deck department aboard ship. Also called deck crew, deck department, or just deck.
• Deck Girders - Continuous longitudinals fastened under the deck.
• Deck House - A small house erected upon the deck of a ship for any purpose. A low building or superstructure, such as a cabin, constructed on the top deck of a ship.
• Deck Log - Also called Captain's Log. A full nautical record of a ship's voyage, written up at the end of each watch by the deck officer on watch. The principal entries are: courses steered, distance run, compass variations, sea and weather conditions, ship's position, principal headlands passed, names of lookouts, and any unusual happenings such as fire, collision, etc.
• Deck Officer - As distinguished from engineer officer, refers to all officers who assist the master in navigating the vessel when at sea, and supervise the handling of cargo when in port.
• Deck Plate - A metal plate fitting on the deck that can be opened to take on fuel or water
• Deck Prism - A prism inserted into the deck which provides light down below.
• Deck Stepped - A mast that is stepped (placed) on the deck of a boat rather than through the boat and keel stepped. The mast of a deck stepped boat is usually easier to raise and lower and are usually intended for lighter conditions than keel stepped boats.
• Deckhand - Seaman who works on the deck of a ship and remains in the wheelhouse attending to the orders of the duty officers during navigation and maneuvering. He also comes under the direct orders of the bosun.
• Deckhead - The underside of the deck, viewed from below the ceiling.
• Declination - The angular distance North or South of the equator, measured from the center of the earth. It thus corresponds to latitude on the earths surface.
• Deep V - Refers to the shape of a boat's (usually power boat) hull. A deep V hull is usually good at cutting through rough waves at high speeds.
• Deep Waterline - The line to which a vessel is submerged with a full cargo on board.
• Departure - (1) The last position on a chart, when a ship is leaving the land. (2) The number of nautical miles that one place is eastwards or westwards of another.
• Depression - An area of low barometric pressure. The wind circulates clockwise in the Southern Hemisphere and counter-clockwise in the Northern Hemisphere. Generally these are bad weather systems.
• Depth Sounder - An instrument that uses sound waves to measure the distance to the bottom.
• Derelict - Any abandoned vessel.
• Derrick - A hoisting apparatus consisting of a block and tackle rigged at the end of a beam.
• Design Waterline (DWL) - Also length waterline or load waterline (LWL) - This is the length of the boat where it meets the water when loaded to its designed capacity.
• Deviation - (1) Differences between the compass reading and an actual magnetic direction caused by magnetic forces in the vicinity of the compass, which are usually the result of masses of metal, speaker magnets, etc. (2) Vessel departure from specified voyage course.
• Deviation Card - A listing of a particular boat's steering deviation on each point of the compass
• Devil - Caulker's name for the seam in the upper deck planking next to a ship's waterways. There was very little space to get at this seam, making it a difficult and awkward job. This is the origin of the expression "Between the devil and the deep blue sea, since there is only the thickness of the ship's hull planking between this seam and the sea. also known as the garboard seam.
• Devil to Pay - Old seafaring term meaning something very difficult or awkward. see Devil
• Dewatering - In controlling damage, to pump out a compartment. ¹
• Dewpoint - Temperature at which moist air becomes saturated
• Dingbat - Slang term for a small swab made of rope and used for drying decks.
• Dinghy - A small open boat often used as tender and lifeboat for a larger craft; a small open boat, usually carried aboard a yacht for going ashore
• Dink - Nickname for a dinghy
• Dirk - A small naval sword worn by midshipmen or their equivalents when in full dress uniform.
• Disabled Ship - When a ship is unable to sail efficiently or in a seaworthy state as a result of engine trouble, lack of officers or crew, damage to the hull or ship's gear.
• Discharges - An essential document for officers and seamen as it serves as an official certificate confirming sea experience in the employment for which he was engaged.
• Disembark, Debark - Leave the vessel.
• Dismast - The loss of a mast on a boat.
• Displacement - The weight of a floating boat measured as the weight of the amount of water it displaces. A boat displaces an amount of water equal to the weight of the boat, so the boat's displacement and weight are identical.
• Displacement Hull - A type of hull that plows through the water, displacing a weight of water equal to its own weight, even when more power is added.
• Displacement Speed - The theoretical speed that a boat can travel without planing, based on the shape of its hull This speed is 1.34 times the length of a boat at its waterline. Also known as hull speed. 
• Distance Made Good - The distance traveled after correction for current, leeway and other errors that may not have been included in the original distance measurement.
• Distress Signals - Any signal that is used to indicate that a vessel is in distress and needs help. Flares, smoke, audible alarms, EPIRB, electronic beacons and others are all types of distress signals.
• Ditty Bag - A small bag for carrying or stowing all personal articles.
• Ditty Box - A small wooden box, with lock and key, in which seamen keep sentimental valuables, stationery, and sundry small stores.
• Diurnal - Daily; occurring once a day.
• Dividers - A navigational tool used to measure distances on a chart.
• Dock - The area a boat rests in when attached to a pier or wharf; also the act of taking the boat to the pier to secure it
• Dodger - Screen of cloth or other material to give the crew protection against the weather, wind and water spray.
• Dog - Heavy latch by which doors, hatches, portholes, etc., are secured; verb - to latch
• Dog Watch - see Watch
• Dog's Breakfast - An old salt I know uses this term in reference to a "tangled mess of lines".
• Doghouse - The short deckhouse or main hatchway which is raised above the level of the cabin top or coachroof.
• Doldrums - The area of calm which lies inside the trade winds near the equator.
• Dolphin - A mooring buoy or spar. A group of piles driven close together and bound with wire cables into a single structure.
• Dolphin Striker - A short spar under the cap of the bowsprit used for holding down a jib boom.
• Donkey Boiler - A steam boiler on a ship deck used to supply steam to deck machinery when the main boilers are shut down.
• Donkey Engine - An auxiliary engine used for furnishing power for a variety of small mechanical chores.
• Donkey House - The structure on deck where the donkey engine is located.
• Donkey's Breakfast - Merchant seaman's name for his bed or mattress.
• Donkeyman - Crew who tends a donkey boiler, or engine, and assists in engine-room.
• Door - A passage through a bulkhead or other vertical divider of spaces. Doors can be closed, sometimes with a watertight seal, to prevent progressive flooding.*
• Dorade - A horn type of vent designed to let air into a cabin and keep water out.
• Dory - A hard-chined dinghy with flared sides, considered a useful weight-carrying work boat.
• Double Bottom - General term for all watertight spaces contained between the outside bottom plating, the tank top and the margin plate. The double bottoms are sub-divided into a number of separate tanks which may contain boiler feed water, drinking water, fuel oil, ballast, etc.
• Double Clews- An old term for getting married.
• Double Ender - Any Boat Designed with a pointed bow and stern.
• Doubler Plate - An extra plate of the same strength or stronger than the original plating secured to the original plating for additional strength.
• Doubling - Name given to that portion of the mast of a large sailing vessel where an upper mast overlaps the lower mast, as a topmast with the lower mast.
• Douse - To take down a sail quickly; the entire action of getting a sail out of the wind and furling it.
• Downhaul - (1) Line attached to the bottom of the boom used to flatten the sail by pulling the boom down, and thus tightening the luff of the sail. (2) A line used for hauling down a jib or staysail.
• Downwind - In the direction the wind is blowing. A boat sailing downwind, away from the wind source with the sails let out all the way, is running with the wind.
• DR - see Dead Reckoning
• Draft - (1) The depth of the boat below the waterline; the amount of vertical distance from a boats water line to the bottom of it's keel. (2) The depth of water necessary to float a vessel (3) The belly or chord depth of the sail, its fullness
• Draft Marks - On ships, the stern and stem are marked in feet to show the draft or depth of the vessel.
• Drag - (1) The resistance to movement. (2) An anchor drags when its flukes do not hold.
• Draw - (1) A sail is said to be drawing when it is full of wind. (2) Said of a vessel to indicate her draft. e.g., she draws 10 feet.
• Drawbridge - A bridge that can be raised vertically to allow boats to pass underneath.
• Dress Ship - To decorate a ship with flags in celebration of certain occasions.
• Drift - (1) Speed or velocity of current (2) The leeway, or movement of the boat, when not under power, or when being pushed sideways while under power.
• Drift or Drift Pin - A round bar driven through heavy wooden parts to hold the parts together. The ends of the bar may be hammered round over a washer. *
• Drift Ice - Ice in an area containing several small pieces of floating ice, but with total water area exceeding total area of ice.
• Drive - A ship drives when her anchor fails to hold and she is at the mercy of wind and tide, or when she can make no progress against the wind.
• Drogue - Any object used to increase the drag of a boat and slow her down. Typically shaped like a parachute or cone opened underwater, drogues decrease a boat's speed in heavy weather. Also see sea anchor.
• Dry Cargo - Merchandise other than liquid carried in bulk.
• Dry Dock - A dock into which a vessel is floated, which when raised lifts the boat out of the water. Can also be a watertight basin with one end open to the sea that can be closed and sealed with a gate, thus allowing the basin to be pumped out. This facility allows inspections, painting and repairs to be made on the hull and any underwater machinery.
• Dry Storage - Storing on land. Many small boats are placed in dry storage over the winter.
• Ducts - Tubes used to move air, such as to ventilate an enclosed area.
• Dunnage - Any material, permanent or temporary, that is used to ensure good stowage, and protect cargo during carriage.

E  [ Echo ] - [meaning]

• Earing - A small line used to fasten the upper corners of a square sail to its yard.
• Ease, Ease Off - To let out a line or sail slowly; to slacken or relieve tension on a line; to take pressure off.
• Ease the Sheets - To let the sheet out slowly while maintaining control.
• East - One of the 4 cardinal compass points. East is at 90° on a compass card.
• East Wind, Easterly Wind - A wind coming from the east.
• Ebb, Ebb Tide - The falling tide when the water recedes out to the sea and the water level lowers; a period or state of decline.
• Echo Sounder - An electrical depth sounder or fish finder that uses sound echoes to locate the depth of objects in water. It does so by timing the sound pulses.
• Eddy - A small local current usually caused by tidal streams  as they ebb and flow around or against obstructions.
• Embargo - A temporary injunction against ships or cargo to prevent their arrival or departure in time of war.
• Embarkation/Embark - To go aboard the vessel; to put onboard a vessel.
• Emergency Tiller - A tiller that is designed to be used in the event that wheel steering fails.
• Engine Bed - A structure of wooden or metal supports that make up the mounting for a ship's engine.
• Engine Order Telegraph - A set of mechanical signaling devices, connected by cables, by which engine commands are passed from the pilot house to the engine room and by which the engine room responds. ¹
• Engine Room - Where the engines of a ship are confined.
• Ensign - (1) A nautical version of the national flag of the country usually flown at the stern. (2) Adopted by the United States Navy in 1862, the rank of a young officer equivalent to that of midshipman
• Entry - The shape of the fore-body of a ship as it thrusts through the sea. A vessel with a slim bow is said to have a fine entry.
• EPIRB - Emergency Position Indicating Radio Beacon. An emergency device that uses a radio signal to alert satellites or passing airplanes to a vessel's position.
• Equator - An imaginary line around the center of the earth at 0° of latitude.
• Equinoctial - The great circle on the celestial sphere in the plane of the earth's equator; also called the celestial equator. The sun is on the equinoctial twice a year, on the equinoxes, March 21 and September 23. On these days the sun rises at 6 a.m. and sets at 6 p.m. (local time) at every place on earth.
• Estimated Position - A position based on estimations of a boat's position using estimated speed, currents, and the last known position/fix - of the boat.
• ETA - Estimated time of arrival
• ETD - Estimated time of departure
• Even Keel - When a boat is floating on its designed waterline, upright without any list to either side, it is said to be floating on an even keel.
• Eye - A loop or hole which is spliced or tied on the end of a line
• Eye of the Wind - Direction from which the wind is blowing; an unsailable sector between close hauled headings.
• Eye Splice - [image] - A permanent loop spliced in the end of a line, sometimes around a thimble.
• Eyebolts - Metal bolts with an eye in the end.

F  [ Foxtrot ] - [meaning]

• Fag Out - The tendency of the strands of a line to fray out at the ends.
• Fair - (1) In good condition. (2) To adjust to proper shape or size.
• Fair Wind - Term applied to the direction of the wind when it is favorable to the course being steered.
• Fairlead - A fitting used to guide a line in a particular direction without chafing.
• Fairway - A navigable channel in a body of water.
• Fake - One circle of a coil or rope. To coil or arrange a rope ornamentally with each fake flat, or almost flat, on the deck, usually in a circle or figure-of-eight pattern. Sometimes called "Cheesing down".
• Fall - The part of the tackle which is hauled upon; a hoisting rope or chain, especially the part of rope or chain to which power is applied.
• Fall Off - To change direction so as to point farther away from the wind. Also Bear Away, Bear Off or Head Down. The opposite of heading up.
• False Keel - An additional keel secured outside the main keel, usually as protection in the event of grounding.
• Fang - Valve of a pump box; to prime a pump.
• Fantail - Overhanging part of  a vessel's stern. The area of the upper deck of a ship that is nearest the stern.
• Farewell Buoy - Buoy at seaward end of channel leading from a port.
• Fast - Said of an object that is secured to another; attached, fixed, secured.
• Fast Ice - Ice extending seaward from land to which it is attached.
• Fasten - To make secure
• Fastening - An item such as a nail, screw, rivet or other device used to fasten objects together.
• Fathom - A unit of measurement relating to the depth of water or to the length of line or cable; one fathom is 6 feet or 1.83 meters
• Fathometer - A depth measuring device.
• FCC Rules - Federal Communications Commission Rules governing radio equipment and operation in the United States.
• Feather Spray - Foaming water that rises upward immediately before stem of any craft being propelled through water.
• Feathering - Sailing upwind so close to the wind that the forward edge of the sail is stalling or luffing, reducing the power generated by the sail and the angle of heel. Also known as pinching.
• Feathering Oars - The turning of the blade of an oar from the vertical to the horizontal while it is being taken aback for the next stroke. This reduces the windage on the blade thus reducing the effort expended.
• Feathering Prop - A propeller that can have the pitch of its blade changed to reduce drag when not in use.
• Fend Off - To prevent contact with an object while bringing the ship alongside.
• Fender - A protective cushion of durable material hung from the sides of a boat to protect it from rubbing or chafing against a dock or another boat.
• Ferry - A vessel designed for the transport of people or goods from one place to another on a regular schedule. 
• Fetch - (1) The distance that the wind and sea has to travel over open water unimpeded by land; the longer the fetch, generally the higher the waves. (2) Also to reach someplace, especially in adverse conditions. When sailing close-hauled, being able to arrive at some point without tacking.
• Fid - A pointed tool used to separate strands of rope.
• Fiddle - A small rail on tables and counters used to keep objects from sliding off when the vessel rolls and pitches.
• Fiddle Block - A double block where the two sheaves lie in a plane one below the other, rather than alongside each other.
• Fiddler's Green - A sailor's paradise where amusements were plentiful, and the women were accommodating.
• Fiddley Deck - A partially raised deck over the engine and boiler rooms, always around the smokestack, to let the hot air and fumes escape.
• Field Ice - Ice pack whose limits cannot be seen from ship.
• Fife Rail - A rail around the mast or on the bulwarks with holes for belaying pins to which lines or halyards are attached.
• Figure Eight Knot - [image] - A stopper knot in the form of a figure eight, placed in the end of a line to prevent the line from passing through a grommet, block, or other fitting.
• Figurehead - An ornamental carved and painted figure on the stem of the vessel.
• Fin Keel - A keel that is narrow and deeper than a full keel. It looks like a fish's fin extending below the boat, and the boat usually has a rudder mounted some distance aft, often on an additional keel-like extension called a skeg.
• Finger Pier - A small pier that projects from a larger pier.
• Fireman - An unlicensed member of the engine room staff whose duties consist in standing watch in the boiler room and insuring the oil burning equipment is working properly.
• First Assistant Engineer - Usually handles engine maintenance. Assigns duties to unlicensed personnel and monitors and records overtime. Consults with Chief regarding work priorities.
• First Mate (Chief Mate) - Directly responsible for all deck operations (cargo storage and handling, deck maintenance deck supplies). Assigns and checks deck department overtime. Ship's medical officer.
• Fisheries - General term used to denote all activities connected with the catching of fish by any means.
• Fisherman Anchor - A traditionally shaped anchor having flukes perpendicular to the stock of the anchor and connected by a shank. These are less common than modern anchors such as the plow and lightweight anchors.
• Fisherman's Bend - A knot used to fasten a line or cable to the anchor.
• Fishhook - Slang sailing expression for a piece of metal or shroud that can cut or stab you.
• Fitting-Out - The general preparation of a vessel to make ready for the sea in all respects.
• Fix - A vessel's position determined by observation and navigational data.
• Fixed Light - A navigational light with a steady beam of light, having no intervals of darkness.
• Flag of Convenience - Registry of the vessel is foreign to that of the country in which the company that owns the ship is located.
• Flag Officer - All naval officers with the rank of rear admiral (or its equivalent) and above.
• Flags - Nautical Flag meanings can be found here.
• Flagship - The ship that carries an admiral's flag.
• Flake - (1) To lay a line out in coils so that it can run without fouling. (2) Folding a sail in layers on the boom.
• Flame Arrester - A safety device used to prevent or stop unwanted flames.
• Flare - (1) The outward curve of a vessel's sides near the bow. (2) A distress signal.
• Flashing Light - Used to describe a light that blinks on and off, where the period of light is shorter than the period of darkness separating the flashes.
• Flatten In - To trim the sheets in.
• Fleet - A company of vessels sailing together.
• Fleeting - Shifting the moving block of a tackle from one place of attachment to another place farther along to give more advantage.
• Flemish Down - To lay down the unused portion of a rope or line in a fancy manner similar to figure-of-eights, ready to run out without kinking.*
• Flemish Horse - The short foot rope at the end of a yard at the outer corner of a square sail used when reefing or furling.
• Floating Dry Dock - A hollow platform or enclosure which can be partially flooded, placed under a vessel, then pumped dry to lift the vessel out of the water so that repairs may be made.*
• Flood - (1) To fill a space (room) with water; (2) A rising tide.
• Floor - Lower part of a transverse frame running each side of the keelson to the bilges; a virtually horizontal platform extending to the ship's sides.
• Floorboards - The surface of the cockpit on which the crew stand.
• Flotilla - A squadron of small ships.
• Flotsam - Debris floating on the water surface; Any part of the wreckage of a ship or her cargo which is found floating on the surface of the sea.
• Flower of the Winds - Old expression for the engraving of the wind-rose on charts.
• Fluke - (1) The portion of an anchor that digs securely into the bottom, holding the boat in place. (2) The two triangular parts which make up a whale's tail.
• Fluky - Said of a wind when it is light and variable in direction, not blowing steadily from any direction.
• Flush Deck - A deck whose top side is flush.
• Fly - The wind direction indicator on the masthead.
• Fly Boat - Fast boat used for passenger and cargo traffic in fairly sheltered waters.
• Flyer - In sailboat racing, to take to opposite tack of the rest of the fleet when behind, hoping that the wind will shift to your benefit.
• Flying Bridge - The highest navigation bridge. It usually includes an added set of controls above the level of the normal control station for better visibility.
• Flying Dutchman - Old legend of a Dutch skipper who, in a strong gale, swore by Donner and Blitzen that he would beat into Table Bay in spite of God's wrath. His ship foundered and he was condemned to go on sailing eternally in his attempt to reach Table Bay. There was a superstition among sailors that anyone who set eyes upon this "ghost ship" would die by shipwreck.
• Fo'c'sle - An abbreviation of forecastle.
• Fog Signals - A series of sound signals required by COLREGS to prevent collisions at sea.
• Foghorn - A device for issuing fog signals, used for giving a warning of a vessel's presence in fog. These signals are also  made by lighthouses.
• Following Sea - A sea with waves approaching from the stern of the boat; a sea in which the waves are moving in the same direction as the vessel
• Foot - (1) The bottom edge of a sail. (2) Sailing slightly more away from the wind than close hauled to increase the boat speed.
• Footropes - On a square-rigged ship, the ropes which hang below a yard upon which the topmen stand while aloft furling or reefing a sail. They were supported by ropes from the yard known as "stirrups".
• Fore - Towards, near, or at the bow; Prefix denoting at, near, or toward the bow.
• Fore and Aft - In a line parallel to the ship's keel.
• Fore and Aft Rigged - Sails that lie in the direction of the ship's length and whose luffs abut the masts or are attached to stays.
• Fore Peak - The compartment at the bow of the vessel
• Fore Rake - The forward part of the bow which overhangs the keel.
• Fore Reach - The headway a vessel makes when luffed in the wind; the distance a sailing vessel will shoot up to windward when brought head to head in the act of tacking.
• Forebiter - Sailor's songs sung in the forecastle when the men of a watch were off duty. These were sung for entertainment, thus they were not shanties.
• Forecabin - The cabin towards the front of the vessel.
• Forecast - A weather prediction.
• Forecastle - Also fo'c'sle or fo'csle. Pronounced "foke-sul". The most forward below decks area of a vessel; The crew quarters on a traditional sailing ship forward of the main mast.
• Foredeck - The forward part of a boat's main deck.
• Forefoot - The point where the stem joins the forward end of the keel.
• Foreguy - A line leading forward from the end of a mainsail boom to prevent the boom from swinging inboard while broad reaching or running. also Preventer
• Foremast - The forward mast of a boat with more that one mast
• Forepeak - A space or compartment in the bow of a vessel - The compartment farthest forward in the bow of the boat. Often used for anchor or sail stowage.
• Foresail - A sail placed forward of the mast, such as a jib; the sail set from the foremast on a schooner; the lowest square sail on the foremast of Square Riggers.
• Forestay - A support wire running from the upper part of the mast to the bow of the boat designed to pull the mast forward. A forestay that attaches slightly below the top of the mast can be used to help control the bend of the mast. The most forward stay on the boat is also called the headstay.
• Forestaysail - A sail attached to the forestay as opposed to a jib which is attached to the headstay.
• Foretriangle - The triangle formed by the masthead, the base of the mast at deck level, and the lower end of the headstay.
• Forward - At or toward the bow. Also the fore part of the ship.
• Forward-leading - Said of a line that leads from its point of attachment towards the bow of the ship.
• Fothering - Closing small leaks in a vessel's underwater body by drawing a sail, filled with oakum, underneath her.
• Foul - (1) Generally something wrong or difficult (2) To be tangled (line) or in turmoil (air); to entangle or obstruct (3) In racing, a rules infraction
• Foul Ground - A place not suitable for anchoring.
• Fouled - Any piece of equipment that is jammed, clogged, entangled, or dirtied.
• Fouled Anchor - An anchor which has become entangled with some object on the bottom, or, on weighing, has it's rode or chain wound around its stock or flukes.
• Founder - When a vessel fills with water and sinks.
• Fo’c’sle - See Forecastle
• Foremast - The mast in the forepart of a vessel, nearest the bow.
• Fractional Rig - A design in which the forestay does not go to the very top of the mast, but instead to a point 3/4-7/8 of the way up the mast.
• Frame - A timber or rib of a ship running from the keel to the side rail; the transverse strengthening members in a ship's hull that extend from the keel to the deck or gunwale. The frames form the shape of the hull and act as a skeleton on which the hull planking is secured.
• Frame Spacing - The distance between frames.
• Frap - To bind together in order to increase tension or to prevent from blowing loose.
• Frazil - Small, cake-shaped pieces of ice floating down rivers.
• Free - (1) Clear, not tangled. (2) sailing free: a vessel is sailing free when her sheets are eased. (3) running free: to sail with the wind from astern.
• Free Port - A port free of customs duty and most customs regulations.
• Free Pratique - Clearance by the Health Authorities.
• Freeboard - The distance from the gunwale to the water. Most often this will vary along the length of the boat.
• Freeboard Deck - The uppermost complete deck of a ship having a secure means of closing all openings to be fully watertight.
• Freeing Port - An opening in the bulwark or rail for discharging large quantities of water, when thrown by the sea upon the ship's deck. Some ships have "swing gates" which allow water to drain off but which automatically close from the pressure of sea water.
• Freight - Goods transported in a ship, or the money paid for such goods.
• Freshen the Nip - To veer or haul on a rope, slightly, so that a part subject to nip or chafe is moved away and a fresh part takes its place.
• Fronts - Used in meteorology to describe boundaries between hot and cold air masses. This is typically where bad weather is found.
• Fuel Dock - A dock dedicated for dispensing diesel oil or gasoline. The fuel dock is for short-term use.*
• Full and By - Sailing as close to the wind as possible with all sails full and drawing.
• Full Keel - A keel that runs the length of the boat.
• Fully Battened - A sail having battens that run the full horizontal length of the sail.
• Fully Stayed - A mast supported by the use of lines or wire known as stays and shrouds.
• Furl - To fold or roll a sail and secure it to its main support
• Furniture - The essential fittings and equipment of a ship, such as anchors, rigging, masts, davits, derricks, winches, etc., excluding her consumable stores such as water, fuel and victuals.
• Futtock - A curved or vertical timber that when paired with a floor or additional futtocks makes the frame of a wooden ship.
• Futtock Shrouds - Short shrouds which give support to the top of a lower mast.
• Futzing - Meddling or fooling around.

G  [ Golf ] - [meaning]

• Gadget - Any little handy contraption such as a scraper or sailmaker's palm, etc.
• Gaff - (1) A spar that holds the upper side of a four sided gaff sail. (2) A pole with a sharp hook at the end used to get a fish on board.
• Gaff Rig - Any sailboat with a four-sided mainsail, defined by two booms, one located on the bottom, perpendicular to the mast, and another, located on top, at an angle from the mast.
• Gaff Sail - A four sided sail used instead of a triangular main sail. Used on gaff rigged boats.
• Gaff Topsail - A light triangular or quadrilateral sail set over a gaff.
• Gale - An unusually strong wind. In storm-warning terminology, a wind of 34 to 47 knots (39 to 54 miles per hour or 62-87 kilometers per hour).
• Galleon - A development of the carrack, with the high forecastle eliminated.
• Gallery - In larger sailing warships, the walk built out from the admiral's or captain's cabin and extending beyond the stern. Often decorated with carved and gilded work, they were also covered and enclosed with elaborate glass windows.
• Galley - (1) The kitchen area of a boat. (2) Very old fighting ship propelled by oars.
• Galley Pepper - Sailor's term for soot or ashes which sometimes fell into food while it was being cooked.
• Galley Slave - A prisoner sold in the slave market. He was forced to serve in the war galleys, where he pulled on one of the oars.
• Gallows Frame - A frame used to support the boom when the sail is down.
• Galvanizing - The process of coating one metal with another, ordinarily applied to the coating of iron or steel with zinc. The chief purpose of galvanizing is to prevent corrosion.
• Gammon Iron - Circular iron band used to hold a bowsprit on the stem of a sailing vessel.
• Gangplank - A board with cleats, forming a bridge reaching from a gangway of a vessel to the wharf.
• Gangway - A narrow portable platform used as a passage, by persons entering or leaving a vessel moored alongside a pier.
• Garboard - The first plank on the outer hull of a wooden vessel next to the keel. In steel ships, the plating next to the keel, or what is known as strake A.
• Garnet - On a square-rigged ship, a tackle used for hoisting casks and provisions.
• Garters - Slang for the leg irons which were used to secure men under punishment.
• Gasket - Ties used to tie up the sails when they are furled to the boom or yards.
• Gate Valve - A valve with a faucet type handle used to restrict the flow of water in a line
• Gear - A general term for ropes, blocks, tackle, equipment, instruments, riggings, any apparatus used aboard ship; clothing and other personal items taken aboard ship
• Gel Coat - The outer resin surface of a fiberglass boat, usually colored.
• Gellywatte - Old term for the boat used by the captain to go ashore.
• General Quarters - The positions and functions assigned to every member of ship's company to manage emergencies or fight the ship; also, the order spoken to take such positions. ¹
• Gennaker - A large sail that is a cross between a spinnaker and a genoa. Hoisted without a pole, the tack is attached at the bottom of the headstay.
• Genoa - A large foresail or jib that overlaps the mainsail. Also known as a genny. Can be expressed in percentages of overlap, e.g. 150 Genoa is 50% overlap of the mainsail.
• Get Spliced - Slang for getting married. A splice joins two lines together permanently.
• Ghosting - To make headway when there is no apparent wind.
• Gimbals - A system by which an object such as a compass is suspended so that it remains horizontal as the boat heels.
• Gingerbread - Gilded carving and scroll work decorating the hulls of ships.
• Gird - To haul in or bind something together in order to create more space.
• Girdle - Additional thickness of planking on a wooden ship about her waterline to give the vessel more stability.
• Girth - The measurement around the body of a ship. The half girth is taken from the center line of the keel to the upper deck beam end.
• Give-Way Vessel - A term, from the Navigational Rules, used to describe the vessel which must yield to the "Stand-on Vessel" in meeting, crossing, or overtaking situations. also known as the Burdened Vessel
• Glass - In the days of tall ships the barometer was a glass vessel with a thin stem. The fluid in the glass (in most cases water) would move up and down the stem as the pressure of the surrounding atmosphere changed. These movements were used to predict changes in the weather. also the seaman's name for a telescope.
• Global Positioning System (GPS) - A navigation system using satellite signals to fix a position with great accuracy.
• Glory Hole - Any small enclosed space in which unwanted items are stowed when clearing up decks.
• GMT - See Greenwich Mean Time.
• Go About - To turn the boat head-to-wind so as to go about on the opposite tack
• Go Adrift - To break loose from a mooring, anchor or docking.
• Gob Line - A length of rope used in a tug to bowse in the towrope. Gog rope.
• Going to Weather - To sail against the prevailing wind and seas.
• Gondola - A small boat, highly ornamented, with a high rising stem and sternpost. Used on the canals of Venice, it is propelled by  a man standing near the stern using a single oar
• Gone Aloft - Sailor's phrase for a seaman who has died.
• Gooseneck - The fitting which connects the boom to the mast.
• Goose-Wings - Indicates the jib or staysail being boomed out on the opposite side of the mainsail in a following wind, giving a large amount of sail area presented to the wind. see Wing and Wing. The term originates, however, from square riggers, and means to haul the
  (weather) tack of a square sail forward, to encourage it to fill when the vessel is hauled so closely on the wind as to begin to backfill the sail.
• GPS - See Global Positioning System.
• Grabrail - A pillar or handhold on a boat - Hand-hold fittings mounted on cabin tops and sides for personal safety when moving around the boat.
• Grapnel, Grapple - A small multi-pronged anchor used on dinghies and small boats. Also used to drag along the bottom to recover something that has sunk.
• Grave, to - see Bream
• Great Circle - The largest circle which can be inscribed on a sphere by a plane that cuts through the center of the sphere. On the earth, the equator is a great circle, as are all the meridians of longitude which pass through both poles. The shortest distance between two points on the earth's surface lies along the great circle which connects the two points.
• Green Buoy/Can - A can buoy. A cylindrical buoy painted green and having an odd number used in the United States as a navigational aid. At night they may have a green light. Green buoys should be kept on the left side when returning from a larger body of water to a smaller one.
• Green Daymark - A navigational aid used in the United States and Canada to mark a channel. Green triangular daymarks should be kept on the left when returning from a larger to smaller body of water.
• Greenwich Mean Time - GMT for short. Greenwich Meridian Time, also known as Universal Time or Zulu time. A time standard that is not affected by time zones or seasons. It is the time used by navigators in celestial navigation.
• Gripe - The tendency of a sailing vessel to head up into the wind when sailing close hauled. Can be caused by the vessel's overall trim, an ill-balanced hull or rig, or by her overall design.
• Gripes - Small lines or bands used to hold down and secure boats on deck while at sea.
• Grog - Rum diluted with water. In the 1700s the daily ration of rum in the British Navy was diluted with water with the idea of reducing drunkenness. The term groggy was derived from the effects of drinking too much grog.
• Grommet - A ring or eyelet normally used to attach a line, such as on a sail.
• Gross Tonnage - A common measurement of the internal volume of a ship with certain spaces excluded. One ton equals 100 cubic feet; the total of all the enclosed spaces within a ship expressed in tons each of which is equivalent to 100 cubic feet.
• Ground - To touch bottom.
• Ground Swells - Long wave formations during calm or light air formed by waves running into shoaling water
• Ground Tackle - A collective term for the anchor, anchor rode (line or chain), and all the shackles and other gear used for attachment.
• Growler - Small iceberg that has broken away from a larger iceberg.
• GRP - Glass Reinforced Polyester. Commonly called fiberglass, a material used for boat construction.
• Guardrail - The upper deck rail along both sides of a vessel to prevent anyone on board from falling overboard.
• Gudgeon - A ring-shaped fitting into which the rudder pintle is inserted which allows the rudder to pivot.
• Gunkholing - Cruising in shallow water and spending the nights in coves.
• Gunnels - See Gunwhale
• Gunter Rig - Development of the lugsail rig where the sail is cut with a very short luff and lon leech.
• Gunwale - The upper edge of a boat's side; the part of a vessel where hull and deck meet. (Pronounced "gunnel")
• Gusset - A brace, usually triangular, for reinforcing a corner or angle in the framework of a structure.
• Guy - A supporting or steadying line or wire; a line used to control the end of a spar. A spinnaker pole, for example, has one end attached to the mast, while the free end is moved back and forth with a guy.
• Gybe - (Jibe) Turning the boat so that the stern crosses the wind, changing direction. To change direction before the wind onto another tack with the boom coming over by the force of the wind. Caution is needed in this maneuver, especially in heavy wind.
• Gypsy - A windlass or capstan drum.
• Gyres - A large circular ocean current.

H  [ Hotel ] - [meaning]

• H-Beams - Steel beams with cross section like the letter "H."
• Hague Rules - Code of minimum conditions for the carriage of cargo under a bill of lading.
• Hail - To attempt to contact another boat or shore, either by voice or radio.
• Half Hitch - A single turn of line around an object with the end being led back through the bight. It's the basis upon which many nautical knots are constructed.
• Half Seas Over - (1) The condition of a vessel stranded on a reef or a rock when the seas break over her deck. (2) Half drunk; incapacitated by drink.
• Halyard - A line used to hoist or lower a sail, flag or spar. The tightness of the halyard can affect sail shape.
• Hand - A member of the ship's crew.
• Hand Bearing Compass - A small portable compass.
• Hand Lead - A weight attached to a line used to determine depth by lowering it into the water.
• Hand Rail - A hand hold. Usually along the cabin top or ladder.
• Handsomely - To do something carefully and in the proper manner.
• Handy-billy - A movable block and tackle used on board for a variety of purposes, including the handling of cargo in holds.
• Hanging Locker - A locker big enough to hang clothes.
• Hanks - Rings or piston hooks by which sails are attach to stays, usually spring-loaded; metal hooks used to secure a sail to a stay; to hank on a sail is to hook it on a stay using the hanks
• Harbor - A safe anchorage, protected from most storms; may be natural or man-made, with breakwaters and jetties; a place for docking and loading.
• Harbor Dues - Various local charges against all seagoing vessels entering a harbor for the use of the harbor and its facilities; these fees are used to cover maintenance of channel depths, buoys, lights, etc. All harbors do not necessarily have this charge.
• Harbormaster - The official who is in charge of a harbor, enforcing all its applicable regulations.
• Hard Aground - A vessel which has gone aground and is incapable of refloating under her own power.
• Hard Alee - The command given to inform the crew that the helm is being turned quickly to leeward, turning the boat windward
• Hard Chine - An abrupt intersection between the hull side and the hull bottom of a boat.
• Hard Over - Turning the wheel or tiller as far as possible
• Harden-up - To sail a boat closer to the wind - to steer closer to the wind, usually by pulling in on the sheets
• Hatch - A sliding or hinged opening in the deck, providing people with access to the cabin or space below; an opening in a boat's deck fitted with a watertight cover.
• Hatch Covers - Covers for closing up hatchways.
• Hatchway - One of the large square openings in the deck of a ship through which freight is hoisted in or out, and access is had to the hold.
• Haul - To pull in or heave on a line by hand; to pull.
• Haul Around - Change from a run to a reach
• Haul Out - Remove a boat from the water.
• Hauling Part - The part on the object which is hauled upon.
• Hawse - That part of a ship's bow where the hawse holes and hawse pipes are situated.
• Hawse Hole - A hole in the hull for mooring lines, cable, or chain to run through.
• Hawse Pipe - Pipes made of heavy cast iron or steel through which the anchor chain runs; placed in the ship's bow on each side of the stem, or in some cases also at the stern when a stern anchor is used.
• Hawse Plug or Block - A stopper used to prevent water from entering the hawse hole in heavy weather.
• Hawser - A heavy line or cable used for towing, mooring or anchoring a large vessel
• Hazard - An object that might not allow safe operation. A group of rocks just under the water or a submerged wreck could be a navigational hazard.
• Haze - To make life onboard for the crew as uncomfortable as possible, by keeping them at work at all hours, often unnecessarily.
• Head - (1) A marine toilet or the compartment containing a toilet. (2) Generally, the top or forward part. (3) The upper corner of a triangular sail. (4) The top portion of a mast.
• Head Down - To turn the boat away from the wind. also Fall Off.
• Head Sea - A sea which is traveling in the opposite direction to that of the boat
• Head to Wind - Where the boat is pointed directly into the wind, sails luffing
• Head Up - Change direction so as to point closer to where the wind is coming from. The opposite of falling off.
• Headboard - A small wooden, metal or plastic insertion at the head of a mainsail.
• Headed - When the wind shifts toward the bow. Opposite of lifted.
• Header - (1) A wind shift further forward relative to the boats direction or heading. (2) A bar or angle under a deck the same size as deck beams. It is used around stair openings in deck, small hatch openings, or at dead end of longitudinals.
• Headfoil - A grooved metal extrusion fitted on a forestay and used to secure the luff of a sail by holding its bolt rope in place.
• Heading - Direction in which ship's bow is pointing at any instant.
• Headsail - A sail set forward of the foremast on the headstay; a foresail
• Headstay - The stay leading from the mast to the bow
• Headway - The forward motion of a boat through the water. Opposite of sternway.
• Heave - (1) To throw, as to heave a line ashore. (2) An upward pull on a line; to lift (3) The rise and fall of a vessel in a seaway.
• Heave In - To haul in.
• Heave Out - Get out of your bunk.  "Heave out and trice up."*
• Heave To - To stop a boat and maintain position (with some leeway) by balancing rudder and sail to prevent forward movement, a boat stopped this way is "hove to"; such as when in heavy seas. The idea is to bring the wind onto the weather bow and hold the ship in that position, where she can safely and easily ride out a storm.
• Heaves - Upward displacing swells.
• Heaving Line - A light line with a weight on the end used for heaving from ship to shore (or ship to ship) when coming alongside. A heavier cable or hawser is attached which can then be hauled over using the heaving line.
• Heavy Seas - When the water has large or breaking waves in stormy conditions.
• Heavy Weather - Stormy conditions, including rough, high seas and strong winds.
• Heel - (1) To lean over to one side, due to wind pressure on the sails or crew on the side; The amount that a boat is tipped over side-to-side, relative to its normal horizontal position. (2) The after end of a ship's keel. (3) The lower end of a mast.
• Heeling Error - The error in a compass reading caused by the heel of a boat.
• Helm - The apparatus by which a vessel is steered, including the rudder, steering wheel and tiller.
• Helmsman - The one who steers the boat.
• Hemisphere - Half of a sphere. On the globe hemispheres are used to describe the halves of the earth north or south of the equator.
• High Seas - The area of sea not under the sovereignty of nations with a seaboard.
• High Tide - The point of a tide when the water is the highest.
• Highliner - The best of its type of fishing boat. Word originates from a time when the crew used to fish from the deck of a vessel. The best fisherman got the highest place on deck, up in the bow, so his line was the highest above the sea.
• Hike - Leaning out over the side of the boat to to counteract heel and balance it.
• Hiking Stick - An extension to the tiller allowing the helmsman to steer while hiking. This may be desired for improved visibility or stability.
• Hiking Straps - Straps to hook your feet under in cockpit when hiking out.
• Hitch - (1) A knot used to secure a line to another object such as a ring or cylindrical object or to another line; (2) Common term for an enlistment.
• H.M.S. - The prefix placed before the name of a warship of the British Navy to indicate that she is Her (His) Majesty's ship.
• Hobby Horsing - The alternate rise and fall of the bow of a vessel proceeding through waves.
• Hogged - A vessel whose bow and stern have drooped. The opposite of sagged.
• Hoist - To lift or raise, such as a sail or a flag.
• Hold - A general name for the spaces below the main deck designated for stowage of general cargo.
• Hold Fast - A dog or brace to hold objects rigidly in place.
• Holding Ground - The type of bottom that the anchor is set in.
• Holding Tank - A storage tank where sewage is stored until it can be removed to a treatment facility.
• Holiday - A gap unintentionally left uncovered while painting or varnishing.
• Holystone - Sailor's name for a block of sandstone used for scrubbing the wooden decks of a ship; seamen had to get down on their knees to use them. Large holystones were known as "Bibles", while smaller blocks to reach awkward places were known as "Prayer Books"
• Hook - Slang for anchor
• Hoop - On gaff-rigged sailing vessels the luff of the mainsail is secured to the mast by wooden hoops, which slide up or down the mast as the sail is raised or lowered.
• Hoosegow - Jail
• Horizon - Where the water and sky or ground and sky appear to intersect.
• Horn Timber - A heavy longitudinal timber that angles upward from the stern to support the underside of the fantail.
• Horns - (1) The points of the jaws of a boom or gaff where they embrace the mast. (2) The outer ends of the crosstrees.
• Horse Latitudes - Areas of the ocean lying between the mostly westerly winds of the higher latitudes, and the trade winds. These areas usually have prolonged calms, and in the older days of sail it could take quite a while to clear out of this area, by which time the seamen had worked off their "dead horses"
• Horse Marine - An unhandy seaman.
• Horseshoe Buoy - A floatation device shaped like a U and thrown to people in the water in emergencies.
• Hounds - Wooden shoulders attached below the masthead to either side of a wooden mast which originally supported the trestle trees.
• Hove To - Lying nearly head to wind and stopped, and maintaining this position by trimming sail or working engines.
• Hoveller - Person who assists in saving life or property from a vessel wrecked near the coast. Often applied to a small boat that lies in narrow waters ready to wait on a vessel, if required.
• Hovercraft - A vessel used for the transportation of passengers and cargo riding on a cushion of air formed under it. It is very maneuverable and is also amphibious.
• Hull - The main structural body or shell of the boat, not including the deck, keel, mast, or cabin.
• Hull Down - Said of a distant ship when her hull is below horizon and her masts and upper works are visible.
• Hull Speed - The maximum speed a hull can achieve without planing - the fastest a keelboat will go, usually dependent on length of the hull at the waterline
• Hulling - (1) Floating, but at mercy of wind and sea. (2) Piercing the hull with a projectile. (3) Taking in sail during a calm.
• Hurricane - A strong tropical revolving storm of force 12 or higher. In the northern hemisphere hurricanes revolve in a clockwise direction. In the southern hemisphere these storms revolve counterclockwise and are known as typhoons.
• Hydrofoil - A craft more or less similar to the Hovercraft insofar as it flies over water and thus eliminates friction between the water and the hull. Under acceleration it rises above water but remains in contact with the surface through supporting legs or foils.
• Hydrography - The study of the earth's waters.
• Hydrowire - Steel wire, used to support over-the-side sampling apparatus
• Hypothermia - A life-threatening condition where there is loss of body heat; the greatest danger for anyone in the water. As the body loses its heat, body functions slow down, and this can quickly lead to death.

I  [ India ] - [meaning]

• I-Beams - Steel beams with cross section like the letter "I."
• Iceberg - A floating island of ice. Only one-ninth of the total mass of an iceberg is visible above water level.
• ICW - See Intracoastal Waterway.
• Idler - Member of a crew who works all day but does not keep the normal watches.
• In Irons - A sailboat with its bow pointed directly into the wind, preventing the sails from filling properly and stopping the boat. It can be very difficult to get a boat that is in irons back under sail. also known as "In Stays".
• In Soundings - A vessel is in soundings when she is in sufficiently shallow water for soundings to be made and used as an aid in the vessel's navigation.
• Inboard - (1) Toward the center of the boat. (2) An engine that is mounted inside the boat.
• Inches of Mercury - A unit used when measuring atmospheric pressure. 33.86 millibars.
• Indiaman - Any of the large sailing ships engaged in the British trade with India from roughly 1600 to 1880.
• Indulgence Passenger - Person given a passage in one of H.M. ships; usually on compassionate grounds.
• Inflatable - A dinghy or raft that can be inflated for use or deflated for easy stowage.
• Inland Rules - Navigation rules governing waters inside designated demarcation zones
• Inland Waters - Term referring to lakes, streams, rivers, canals, waterways, inlets, bays, etc.
• Inshore - Near or toward the shore
• Inspection Port - A watertight covering, usually small, that may be removed so the interior of the hull can be inspected or water removed.
• International Code of Signals - A set of radio, sound, and visual signals designed to aid in communications between vessels without language problems. It can be used with Morse Code, with signal pennants, and by spoken code letters.
• International Date Line - The line of longitude 180 degrees opposite Greenwich, England, located in the Pacific that marks the date change
• International Rules - Navigation rules governing waters outside designated demarcation zones
• International Waterways - Consist of international straits, inland and interocean canals and rivers where they separate the territories of two or more nations.
• Intracoastal - Domestic shipping routes along a single coast.
• Intracoastal Waterway - A system of rivers and canals along the Atlantic and Gulf Coasts of the United States allowing boats to travel along them without having to go offshore.
• Inverter - Electrical power converter; converts square-wave DC current to sine-wave AC current
• Irish Hurricane - Old sailor's term for a flat calm with no wind.
• Irish Pennants - Loose ends of line left hanging over a ship's side.
• Iron Genny - Auxiliary engine
• Isinglass - The clear, soft plastic material used for dodger window panels
• Isobars - Lines drawn on a weather map indicating regions of equal pressure. When the lines are close together, this indicates a rapid change in air pressure, accompanied by strong winds.
• Isobath - Line on a chart linking points of equal depth. also known as a Depth Contour.
• Isogonic Lines - A line connecting points of equal magnetic variation on a map.
• Itinerary - A schedule of all ports to be visited on a ship's cruise, with dates of arrival and departure and the local agents' names and addresses

J  [ Juliet ] - [meaning]

• Jack - The national flag flown on a jackstaff on the bow of naval ships while anchored.
• Jack Lines - Safety lines, usually of flat webbing, that run along the deck between bow and stern used to attach a tether from a safety harness.
• Jack Nastyface - Nickname for an unpopular seaman.
• Jack Tar - Nickname for a British naval seaman.
• Jack With a Lantern - Used by some seamen to describe St. Elmo's Fire.
• Jackanapes - see Monkey Jacket.
• Jackass Barque - Four-masted sailing ship square-rigged on the two foremost masts and fore-and-aft rigged on the two after masts.
• Jackstaff - A short vertically erected pole at the bow on which the national flag is hoisted on naval ships while at anchor.
• Jackstay - A line or cable secured between two points and used as a support for various purposes.
• Jackyard - A yard or pole extending the head or foot of the topsail beyond the topmast or gaff of a gaff-rigged boat
• Jacobs Ladder - A rope ladder with wooden steps. A rope ladder, lowered from the deck, as when pilots or passengers come aboard.
• Jam Cleat - A cleat designed to hold a line in place without slipping. It consists of two narrowing jaws with teeth in which the line is placed.
• Jaw - The distance between a rope's adjacent strands, giving a measure of the tightness of the lay. The shorter the distance, the harder the lay. When a line has been overused and the lay has become slack, it is said to be slack-jawed.
• Jaws - A fitting holding a boom or gaff to the mast.
• Jenny - A genoa jib. A large jib that overlaps the mast.
• Jerque - Search of a vessel, by Customs authorities, for unreported goods.
• Jetsam - Anything thrown overboard; debris, jettisoned items, floating at sea. Goods deliberately thrown overboard from a ship, for example to lighten her if she is in danger, while flotsam refers to goods accidentally lost overboard or which may float up from a hull of a wrecked ship.
• Jettison - To cast overboard or off. To discard something as unwanted or burdensome. Goods or equipment may be jettisoned to lighten a ship in danger.
• Jetty - A man made structure projecting from the shore. May protect a harbor entrance or aid in preventing beach erosion.
• Jewel Blocks - On square-rigged ships, the blocks attached  to those yards on which studdingsails were set.
• Jib - The foremost sail; a triangular shaped foresail forward of the foremast.
• Jib Netting - A rope net to catch the jib when it is lowered.
• Jib Sheet - The lines that lead from the clew of the jib to the cockpit and are used to control the jib.
• Jib Stay - The stay that the jib is hoisted on. Usually the headstay.
• Jib Topsail - A small jib set high on the headstay of a double headsail rig.
• Jib-boom - Spar forward of bowsprit to extend the foot of the outer jib.
• Jibber the Kibber - The act of decoying a ship ashore by means of false lights.
• Jibe - see Gybe
• Jib-Headed Topsail - A triangular topsail set above the mainsail in a gaff-rigged vessel.
• Jibstay - The headstay on which jibs are hoisted
• Jiffy Reefing - A method of lowering the sail in sections so that it can be reefed quickly.
• Jigger - (1) A light tackle consisting of a double and single block used for many small purposes onboard. (2) Aft sail on the mizzen mast of a yawl or a ketch, or on the jigger-mast of a schooner.
• Jigger-Mast - After mast on a schooner or sailing ship carrying a spanker; usually the fourth mast of a five or six masted schooner.
• Jimmy Bungs - Nickname for a ship's cooper.
• Jockey Pole - A spar used  to prevent the spinnaker guy from fouling on the stanchions.
• Jolly Roger - In lore, the flag flown by a pirate ship - a white skull on a black background with crossed bones below the skull - although there is no evidence that such a flag was ever flown.
• Jumbo - The largest of the headsails; corresponds to the genoa.
• Jump (a line) - To stand at the mast and pull down on a halyard as another crewmate winches it in.
• Jumper Strut - A short strut on a mast angled forward at about 45° which spreads the effective angle of a short jumper stay. This adds stiffness and support to the mast.
• Junction Buoy - Also known as a preferred channel buoy. A red and green horizontally striped buoy used in the United States to mark the separation of a channel into two channels. The preferred channel is indicated by the color of the uppermost stripe. Red on top indicates that the preferred channel is to port as you return, green indicates the preferred channel is to starboard.
• Junk - (1) A sailing vessel common in the Far East. It's flat-bottomed, high sterned, has square bows, and has two or three masts carrying lugsails. (2) Old and condemned rope.
• Jury Rig - A temporary repair or replacement using improvised materials and parts.

K  [ Kilo ] - [meaning]

• Kayak - Eskimo word for a light, covered-in canoe type boat.
• Keckling - Winding small rope around a cable or hawser to prevent damage by chafing. The rope with which a cable is keckled.
• Kedge - (1) A small auxiliary anchor. (2) To kedge is to move a vessel (e.g., a grounded boat) by setting out an anchor and pulling the boat toward it by taking up on the anchor rode
• Keel - [image] (1) The backbone of a vessel, running fore and aft along the center line of the bottom of the hull; the timber at the very bottom of the hull to which frames are attached. (2) A flat surface built into the bottom of the boat to prevent or reduce the leeway caused by the wind pushing against the side of the boat. A keel also usually has some ballast to help keep the boat upright and prevent it from heeling too much. There are several types of keels, such as fin keels and full keels.
• Keel Blocks - Blocks on which the keel of a vessel rests when being built, or when she is in dry dock.
• Keel Stepped - A mast that is stepped (placed) on the keel at the bottom of the boat rather than on the deck. Keel stepped masts are considered sturdier than deck stepped masts.
• Keelhauling - A severe naval punishment for serious offenses in which the victim was hauled from one yardarm to the other under the keel of the ship. The victim rarely survived; he would either be cut to ribbons by the shellfish on the ship's bottom or drown.
• Keelson - A beam attached to the top of the floors to add strength to the keel on a wooden boat.
• Keep Her Full - To keep the sails full and drawing
• Kelter - Good order and readiness.
• Kenning - Sixteenth-century term for a sea distance at which high land could be observed from a ship. Varied between 14 and 22 miles according to average atmospheric conditions in a given area.
• Kentledge - Permanent pip iron ballast specially shaped and placed along each side of keelson. Name is sometimes given to any iron ballast.
• Ketch - A sailboat with two masts. Generally, the shorter mizzen mast is aft of the main mast, but forward of the rudder post, while a similar vessel, the yawl, has the mizzen mast aft of the rudder post. The mizzen mast of a ketch is larger than that of a yawl.
• Killick - Nautical name for an anchor. Originally, was a stone used as an anchor.
• King Plank - The center plank on a wooden deck.
• King Post - A vertical post usually employed as a support - Also called a Sampson post
• King Spoke - The top spoke (usually marked) on the steering wheel when the rudder is centered.
• Kippage - Former name for the equipment of a vessel, and included the personnel.
• Kite - A light sail, such as a spinnaker, used to make the most of light following winds.
• Knee - An angle or channel from deck beam to shell frame taking the place of a bracket.
• Knees - Supporting braces made into a right angle, used for strength when two parts are joined.
• Knock - A wind shift that forces a boat to sail below its mean wind course.
• Knockabout - A type of schooner without a bowsprit.
• Knockdown - A boat that has rolled so that she is lying on her side or even rolled completely over (can be caused by a sudden gust or squall). A boat with appropriate ballast should right herself after being knocked down.
• Knot - (1) A speed of one nautical mile (6,076 feet or or 1,852 meters) per hour. It is incorrect to say knots per hour. (2) A method of attaching a rope or line to itself, another line or a fitting.
• Kraken - Enormous sea monster supposed to have been seen off coasts of America and Norway. Sometimes mistaken for an island.

L  [ Lima ] - [meaning]

• Labor, to - Description of a vessel when she rolls or pitches excessively while underway in heavy seas.
• Lacing - A length of line or thin rope; A line used to attach a sail to a spar.
• Ladder - Stairway of inclined or vertical steps on board ship.
• Lading - That which is loaded into a ship. The act of loading.
• Lagan - Jettisoned goods that cast overboard and are buoyed for subsequent recovery.
• Lagoon - An area of water totally or partially enclosed by coral islands, atolls, and reefs.
• Laid Up - A boat in a dry dock.
• Land Breeze - A wind moving from the land to the water due to temperature changes in the evening, where the temperature of the land falls below the sea temperature.
• Landfall - Arrival at land
• Landlocked - Surrounded by land.
• Landlubber - A person inexperienced with or uncomfortable around boats.
• Landmark - A distinctive fixed reference point that can be used for navigation.
• Lanyard - A Short line used to attach one thing to another - a short rope or cord that secures or attaches an item onboard a boat, usually for keeping it attached to the boat
• Lapper - A large foresail which extends aft behind the mast.
• Lapstrake - The overlapping of wooden planks, used to form the outer surface of a boat's hull.
• Larboard - The original name for the left side of the vessel when facing forward. The name was changed to Port to avoid any confusion with starboard, the right side of the vessel when facing forward.
• Large - Said of vessel sailing with wind abaft the beam but not right aft.
• Lash - To tie something with a line; to secure
• Lashing - A rope used for securing any movable object in place
• Lask - To sail large, with wind about four points abaft beam.
• Lateen - Narrow triangular sail set on a long yard or spar, the forward end of which is hauled down so that it sets obliquely on the mast with a high peak.
• Lateral Resistance - The ability of a boat to keep from being moved sideways by the wind. Keels, daggerboards, centerboards, and leeboards are all used to improve a boat's lateral resistance.
• Latitude - The distance north or south of the equator measured and expressed in degrees. The equator is 0° and the north and south poles are 90°.
• Launch - (1) To float a vessel off the ways in a building yard after it is completed. (2) A small boat used to ferry people to and from a larger vessel.
• Lay - (1) As a command, it means to go in the direction indicated, e.g., "Lay foward" (go up) or "Lay alow!" (come down). (2) Of a line or rope, it refers to the direction in which the strands are twisted. (3) Lay the course: able to fetch a given point when close-hauled
• Lay Aboard - To come alongside. Also known as "Lay Alongside".
• Lay Out - (1) Order to men at the mast to extend themselves at intervals along a yard. (2) To keep a vessel at a certain place until a specified time has elapsed.
• Lay the Land - To cause the land to sink below horizon by sailing away from it.
• Lay Up - To store a yacht away on land for the winter
• Laying on Oars - Holding oars at right angles to fore and aft line of boat with blades horizontal and parallel to surface of water.
• Layline - The direct sailing line in which a racing mark or buoy can be fetched while sailing the desired course
• Lazarette - Compartment in the stern of a vessel used for storage; a storage space below the deck in the cockpit.
• Lazy Guy - A line attached to the boom to prevent it from accidentally gybing.
• Lazy Sheet - A line led to a sail, but is not currently in use. The line currently in use is known as the working sheet. Usually the working and lazy sheets change when the boat is tacked.
• Lazyjacks - Light lines from the topping lift to the boom, forming a cradle into which the mainsail may be lowered.
• Lead - Refers to the direction in which a line goes.
• Lead Line - A line with a weight on the end used to measure depth. The lead is dropped into the water and marks on the line are read to determine the current water depth. The lead usually has a cavity to return a sample of the bottom type mud, sand, etc.
• Leading Block - A single block such as a snatch block used as a fairlead to bring a line in a more favorable direction.
• Leading Marks - Unlit navigational aids for use during the day. They mark a bearing to a channel when they are lined up one above the other. Leading lights are lighted at night and serve the same purpose.
• League - A measure of distance approximately 3 nautical miles. One-twentieth of a degree of latitude.
• Lee - The side of a ship, or a shore location, sheltered from the wind; also used in context to refer to a sheltered place out of the wind, as in the lee of the island; The area to the leeward
• Lee Helm - Sailing with the tiller over to leeward by force of the wind
• Lee Lurch - Heavy roll to leeward with a beam wind.
• Lee Shore - A shore that wind blows onto; it is best to stay well off a lee shore in a storm
• Leeboards - Boards fixed vertically to a boat to prevent leeway
• Leebow - In sailboat racing, to disturb the wind of a windward boat by positioning your boat a bit ahead and to leeward. If done correctly, the disturbed air hitting the windward boat will slow it down, leaving it at a distinct disadvantage and causing it to tack away with a loss of speed and distance
• Leech - After or trailing edge of a sail; the after edge of a fore-and-aft sail and the outer edges of a square sail.
• Leech Line - A line used to tighten the leech of a sail, helping to create proper sail shape.
• Leecloths - Cloths hung on the lee side of a berth to keep one from rolling out of their bunk
• Leeward - Direction away from the wind. In the Rules of the Road, the leeward boat is the one farthest from where the wind is coming from. Opposite of windward.
• Leeway - The sideways movement of a boat caused by either wind or current, usually unwanted. Keels and other devices help prevent a boat from having excessive leeway.
• Leg - The working portion of a cruise between ports. A long cruise may have many legs. The distance sailed on one tack. The course from one race mark to another.
• Length Over All (L.O.A.) - Measured from the most forward part of the fore end to the most after part of the after end of the hull.
• Let Fly - The action of letting go the sheets of a sailing vessel, thus spilling the wind and reducing the forward motion of the boat.
• Letter of Marque - A commission issued, licensing the commander of a privately owned ship to cruise in search of enemy merchant vessels. see Privateer.
• Leviathan - A gigantic sea animal.
• Liberty - Term for a seaman's short leave from his ship, permitting him to go ashore for the day or night.
• Licensed Pilot - A pilot with a license stating that they are qualified to guide vessels in a particular area.
• Lie A-Try - To bring a sailing vessel head to the wind or as close to it as possible in high seas, maintaining a slight forward motion.
• Lie By - To remain nearly alongside another vessel.
• Lie To - See Heave To
• Lieutenant - A naval rank next below that of lieutenant-commander, which is next below that of captain (the equivalent of commander).
• Life Jacket - A device used to keep a person afloat. Also called a life preserver, life vest, PFD or personal floatation device.
• Life Raft - A raft used in case of emergencies, such as sinking or fire.
• Life Vest - A wearable device used to keep a person afloat. Also called a life jacket, life preserver, PFD or personal floatation device.
• Lifeboat - Small boat carried on the vessel and used in case of emergency.
• Lifeboat Drill - The master of every vessel is bound by international law to make the officers, crew and passengers adequately acquainted with the procedures of lowering and the use of lifeboats in case of emergency.
• Lifebuoy, Life Ring - a circular donut-shaped buoy designed to support a person in the water. It is attached to the vessel with a (floating) line so that the person can be hauled back to the boat.
• Lifeline - Stout line or cable fore and aft around the deck of the boat to keep crew from falling overboard.
• Lift - A wind shift that allows a boat to sail above its mean wind course.
• Lifts - On square-rigged ships, the lines which are lead from the masthead to the ends of the yards to support them.
• Lifted - In sailing, to be lifted by a wind shift that allows your boat to be lifted closer to the wind where by it allows you to sail a shorter distance to the next mark, buoy or finish line
• Light - A lit navigational aid such as a lighthouse that can be used at night or in poor visibility.
• Light List - A list of navigational lights arranged in geographical order, giving the position and characteristics.
• Light Load Line - The water line when the ship rides empty.
• Light Port - An opening in a ship's side, provided with a glazed lid or cover for the admission of light.
• Light Sails - Sails, such as the spinnaker, reacher and reaching staysail used when running or reaching
• Lightening Holes - Holes cut in a plate to make it lighter and yet not reduce its strength.
• Lighter - General name for a broad, flat-bottomed boat used in transporting cargo between a vessel and the shore. The distinction between a lighter and a barge is more in the manner of use than in equipment. The term "lighter" refers to a short haul, generally in connection with loading and unloading operations of vessels in harbor while the term "barge" is more often used when the cargo is being carried to its destination over a long distance.
• Lightering - Conveying cargo with another vessel known as a lighter from ship to shore, or vice versa.
• Lighthouse - A structure erected to display a characteristic light as a warning of danger at sea and as an aid to navigation.
• Lightship - A stationary vessel carrying a light used for navigation, serving the same purpose as a lighthouse.
• Lignum Vitae - A smooth hard wood grown in the West Indies which had many maritime uses, such as deadeyes and the sheaves of blocks. Its hardness stood up well to wear, and its smoothness allowed lines to render through easily.
• Limber Holes - Holes in the bottoms of floors or floor timbers for drainage; holes in the bilge crossframes to allow bilge water to drain to the lowest point, which is where the bilge pump would be located.
• Limey - A nickname referring to British seamen. All British ships were to carry a supply of lime juice for issue to the crew as a preventative against scurvy.
• Line - Rope and cordage used aboard a vessel. A particular line generally derives its name from the object it affects.
• Line Gun - A gun used to shoot a messenger line from one ship to another, or to persons stranded.*
• Line Squall - A squally wind sometimes accompanied by rain, observed as a dark cloud stretched across the horizon.
• Liner - A passenger or cargo-carrying ship which is operated between scheduled, advertised ports of loading and discharge on a regular basis.
• Lines - The naval architect's drawings of a ship showing the various sections.
• Linestoppers - A device used to keep a line from slipping, such as a jamcleat.
• Lipper - Small sea that rises just above bows or gunwale.
• Liquid Petroleum Gas - LPG or propane for short. Propane is a common fuel used for cooking and heating. CNG natural gas is considered safer because propane is heavy than air and will sink into the bilge if it leaks, creating the potential for an explosion. Propane is more easily available throughout the world than CNG however, so it is used for most boats outside of North America.
• List - The leaning of a boat to the side because of excess weight on that side; inclination of a boat due to excess weight on one side or the other.
• Lizard - A short length of line with a thimble spliced into the end, used for several purposes.
• LNG Carrier - Liquefied natural gas carrier, perhaps the most sophisticated of all commercial ships. The cargo tanks are made of a special aluminum alloy and are heavily insulated to carry natural gas in its liquid state at a temperature of -2850F.
• Load Water Line (LWL) - A line painted on the side of the vessel to which the vessel sinks when carrying its full load. The water line when a vessel is carrying its full load.
• Lobscouse - A familiar dish at sea before refrigeration was available. It was a stew of salt meat, broken biscuit, potatoes, onions and available spices.
• Locker - A closet or chest-like storage space.
• Lodesman - (definition) by Webster 1913 (print) Loads"man, Lodes"man (?) , n. [Load, lode + man.] A pilot. [Obs.] Chaucer. *
• Lodestar - Sailor's name for the north star, Polaris, which for all practical purposes remains fixed above the north pole, bearing north from everywhere in the northern hemisphere, making it a true aid to navigation.
• Log - (1) A record of all the activities aboard a ship. The Log Book. (2) A device used to measure the distance traveled and speed through the water.
• Log Room - Where a vessel's records, especially engineering records, are kept. *
• Loggerhead - The wooden bit in the stem of a whaling boat around which the harpoon line was controlled.
• Long Glass - an optical device for magnifying distant objects, consisting of one telescoping barrel with lenses. *
• Long Splice - Joining the ends of two lines without increasing the thickness over the length of the splice, so that the splice will pass freely through a block.
• Long Ton - 2,240 pounds (1016.05 kilograms)
• Longitude - Imaginary lines drawn through the north and south poles on the globe used to measure distance east and west of the prime meridian at Greenwich, England (designated as 0°).
• Longitudinal - A bulkhead, frame, or longitudinal stiffener, running fore and aft.
• Longsplice - Sailor slang for marriage.
• Loods -  Pronounced "loads," is the official Dutch title for a ship's pilot.*
• Lookout - A person designated to watch for other vessels and hazards.
• Loose - To loose a rope is to let it go
• Loose-footed - A sail attached to the boom at the tack and clew, but not along the foot, or a fore-and-aft sail which is set without a boom.
• Loran - Long-range navigation system that uses radio signals transmitted at specific times. An onboard receiver computes position by measuring the difference in time of signal reception. This system is being phased out in favor of GPS.
• Low and Aloft - An expression describing a sailing ship set with every sail she can carry.
• Lubber - A clumsy and unskilled man.
• Lubber's Hole - An opening in the floor of the tops of a square-rigged vessel's masts, giving access from below. Timid crew climbing the rigging preferred to go through this hole to reach the top rather than over the futtock shrouds, the path taken by more experienced sailors.
• Lubber's Line - A line on the compass aligned with the centerline of the vessel that indicates the vessel's compass heading. Since it points to the vessel's bow, it enables a course to be steered by bringing the lubber's line to the point on the compass card which indicates the desired course.
• Lucky Bag - The place where lost items may be reclaimed, or after a time claimed anew.*
• Luff - The forward edge of a fore-and-aft sail
• Luff Up - To steer the boat more into the wind, thereby causing the sails to flap or luff.
• Luffing - To luff or luff up is to head into the wind, causing sails to flutter.
• Lug or Lugsail - A four sided sail bent onto a yard. Similar to a gaff sail, but with a wider throat.
• Lugger - A sailing vessel rigged with lugsails.
• Lugs - Metal or plastic pieces attached to a sail's luff that slide in a mast track to allow easy hoisting of the sail.
• Lumper - Man employed in unloading ships in harbour, or in taking a ship from one port to another. Paid "lump" sum for services.
• Lurch - Sudden and long roll of a ship in a seaway.
• Lying Ahull - A boat that is letting herself be subjected to prevailing conditions without the use of sails or other devices. Lying ahull is usually not preferred to other actions because a boat may tend to lie with her beam to the waves and the wind parallel to the waves. This can cause a boat to roll excessively and even become knocked down.
• Lying To - Said of a vessel when stopped and lying near the wind in heavy weather. See Heave To

M  [ Mike ] - [meaning]

• Magnetic Bearing - The bearing of an object after magnetic variation has been considered, but without compensation for magnetic deviation.
• Magnetic Course - The course of a vessel after magnetic variation has been considered, but without compensation for magnetic deviation.
• Magnetic Deviation - Compass error. The difference between the reading of a compass and the actual magnetic course or bearing due to errors in the compass reading. These errors can be caused by metals, magnetic fields and electrical fields near the compass. The act of checking for magnetic deviation is called swinging.
• Magnetic North - The direction to which a compass points. Magnetic north differs from true north because the magnetic fields of the planet are not exactly in line with the north and south poles. Observed differences between magnetic and true north is known as magnetic variation.
• Magnetic Variation - The difference between magnetic north and true north, measured as an angle. Magnetic variation is different in different geographic locations, so the nearest compass rose to each location on a chart must be used.
• Main Beam - Transverse structural member supporting the deck and, in most modern sailboats, the deck-stepped mast; also the designated location of the ship's Official Number and (in some instances) Tonnage (affixed to or cut into the beam)
• Main Deck - The uppermost complete deck.
• Main Mast - The tallest mast; the forward mast of a yawl or ketch; the mast furthest aft on a schooner
• Main Topsail - A topsail on the main mast.
• Mainsail - The principal sail that is set on the main mast.
• Mainsheet - The line that controls the angle of the mainsail in its relation to the wind.
• Make Fast - To attach a line to something so that it will not move.
• Make Way - Moving through the water.
• Man the Yards - On square-rigged ships, a form of ceremonial salute to honor the visit of a high official. The yards were lined by men standing upon them, and there was also a man standing on the truck of each topgallant mast.
• Manhole - A hole in a tank, boiler or compartment on a ship, designed to allow the passage of a man for examination, cleaning, and repairs.
• Manifest - A document containing the ship's name and port of registry, a full list of the ship's crew, passengers, full details of her cargo, and other relevant information.
• Manila - Before the introduction of man-made fibers, much of the rope used at sea was made from manila. Made from the fibers of banana plants in the Philippines, manila did not rot when it was exposed to seawater.
• Marconi Rig - The most common type of sail used today, a triangle-shaped mainsail defined by the mast and one horizontal boom perpendicular to the mast.
• Marina - A place where boats can find fuel, water and other services. Marinas also contain slips where boats can stay for a period of time.
• Mariner - In general, a person employed in a sea-going vessel. In some cases, applied to a seaman who works on deck.
• Marines - Military persons expert at small arms carried aboard warships to kill enemy officers, gunners, etc., also may be used to enforce the captain's authority.*
• Mark - An object used as a reference point while navigating.
• Marl - To wrap a small line around another.
• Marline - Pronounced "marlin" - small line used for whipping, seizing, and lashing.
• Marling Hitch - [image] - Used for lashing down sails, awnings, etc., a series of round turns where the end is passed over the standing part and under the bight and pulled taut on each turn.
• Marlinspike - Pointed tool used for line work, for opening line strands for splicing, and especially for prying tight knots apart.
• Marlinspike Sailor - One who is adept at splicing, knotting, and working with line and canvas.
• Maroon - To deliberately put a sailor ashore and leave him there while the ship sails away.
• Marry, to - The operation of bringing two lines together; term also applied to other objects.
• Marry the Gunner's Daughter - Old Navy nickname for a flogging, particularly when across a gun.
• Martingale - On square-rigged ships, the stay which holds the jib-boom down against the pull of the fore topgallant-mast stays.
• Mast - The vertical pole or spar that supports the boom and sails. a mast on a mechanically propelled vessel holds electronics antennas, lights, etc.
• Mast Boot - A protective cover wrapped around the mast at the deck on a keel stepped boat to prevent water from entering the boat.
• Mast Head - The top of the mast
• Mast Hoops - Rings around a mast which can slide vertically, attached to the forward edge of a sail, which hold the sail in place.*
• Mast Partners - Reinforcements for a mast where it passes through a deck.*
• Mast Slot/Groove - The opening up the back (aft) edge of the mast in which the mainsail luff rope slides when it is hoisted. Some masts have an external sail track.
• Mast Step - The fitting in the bottom of the boat in which the bottom or heel if the mast sits.
• Mast Tangs - Fittings on the mast to which the forestay and shrouds attach.
• Mast Track - A track or groove in the back of the mast to which the sail is attached by means of lugs or the bolt rope.
• Master - The Captain of a vessel. Highest officer aboard ship. Oversees all ship operations. Keeps ships records. Handles accounting and bookkeeping. Takes command of vessel in inclement weather and in crowded or narrow waters. Handles communications.
• Master-At-Arms - The person empowered by the captain to be armed if necessary to maintain order or make arrests.*
• Masthead - The top of a mast.
• Masthead Light - Also known as a steaming light. The masthead light is a white light that is visible for an arc extending across the forward 225° of the boat. When lit the masthead light indicates that a vessel under power, including sailboats with engines running. Masthead lights are usually located halfway up the mast rather than at the top.
• Masthead Rig - A design in which the forestay runs to the top of the mast.
• Mate - A deck officer ranking next below that of master. Usually divided into first, second, third, etc. to indicate seniority.
• MAYDAY - An internationally recognized distress signal used on a radio to indicate a life threatening situation. Mayday calls have priority over any other radio transmission and should only be used if there is an immediate threat to life or vessel. Mayday comes from the French M'aidez which means help me. For urgent situations that are not immediately life threatening there is the PAN PAN identifier. Less urgent messages such as navigational hazards should send a SECURITE message.
• Mean Low Water (MLW) - A figure representing the average low tide of a region.
• Mean Lower Low Water (MLLW) - There are two low tides in each tidal cycle (so usually two low tides in each day). These two low tides are not quite the same height because one tide is generated by the gravitational interaction with the sun (which is small), and the other is generated by the gravitational interaction with the moon (which is not so small). Since the two low tides (or water levels) are different levels of low, one is naturally the higher low water (higher low tide) and the other is the lower low water (lower low tide). So Mean Lower Low Water is the average of the lower low water height of each tidal day (ie average of the lowest low tide from each day). The averages are taken over a period called the National Tidal Datum Epoch (a 19-year epoch).
• Measured Mile - A course marked by buoys or ranges measuring one nautical mile. Measured miles are used to calibrate logs.
• Mediterranean Berth - A method of docking with a boat's stern to the dock.
• Meet Her - An order to the helmsman to put on opposite rudder to check the swing of the ship.*
• Mercator Projection - Method of producing a chart in which the parallels of latitude and the meridians of longitude intersect each other at right angles.
• Merchant Navy - The merchant ships on the official registers of any nation.
• Meridian - A semi great circle joining the north and south poles. Known as lines of longitude, they cross the equator and all parallels of latitude at right angles.
• Mermaid - A mythical creature, half human and half fish.
• Mess - Dining room facilities and kitchen for crew separate from the passenger dining room and kitchen.
• Mess Deck - Where meals are eaten
• Messenger - A small line used to pull a heavier line or cable. The messenger line is usually easier to throw, lead through holes or otherwise manipulate than the line that it will be used to pull.
• Messroom - A dining room on a ship.
• Meteorology - The study of weather patterns in order to predict changes in the weather.
• Midchannel Buoy - A red and white vertically striped buoy used in the United States to mark the middle of a channel. Midchannel buoys may be passed by on either side.
• Middle Ground - Shoal area between two navigational channels.
• Midshipman - A non-commissioned naval rank. Midshipmen play a part, under supervision, in most of the ship's activities, and are in training  for higher command.
• Midships - In the middle portion of the boat - Roughly halfway between a ship's stem and stern, and where the beam usually is the widest.
• Midwatch - the watch or work shift beginning at midnight, usually lasting until 4:00am or 8:00am.¹
• Mile - Distance at sea is measured in nautical miles, which are about 6067.12 feet, 1.15 statute miles or exactly 1852 meters. Nautical miles have the unique property that a minute of latitude is equal to one nautical mile - Measurement of speed is done in knots where one knot equals one nautical mile per hour.
• Millibar - A unit used to measure the barometric pressure of the atmosphere. 1 millibar equals 0.03 inches of mercury.
• Mizzen - A small sail set on the mizzenmast.
• Mizzenmast - The mast aft of the mainmast in a sailing ship - the shorter mast behind the main mast on a ketch or yawl, or the third aftermost mast of a three-masted schooner or square-rigged ship.
• Mold - A pattern or template. Also a shape of metal or wood over or in which an object may be hammered or pressed to fit.
• Mold Loft - The large enclosed floor where the lines of a vessel are laid out and the molds or templates made.
• Monkey - (1) A small wooden cask in which grog was carried. (2) A type of marine steam reciprocating engine where two engines were used together on the same propeller shaft.
• Monkey Fist - A large heavy knot usually made in the end of a heaving line to aid in accurate throwing.
• Monkey Jacket - A thick serge jacket worn by seamen while keeping watch at night or in stormy weather.
• Monohull - A boat with one hull.
• Mooncusser - Legendary opportunists who lured vessels onto shoals during nights when there was no moonlight to illuminate the coastline.
• Moonraker - On square-rigged ships, a small light square sail set above the skysail in fair weather. If the sail were triangular, it would be called a Skyscraper.
• Moor - To attach a boat to a mooring, dock, post, anchor, etc.
• Mooring - An anchor or weight, permanently attached to the sea floor, with a buoy going to the surface, used to hold the boat in a certain area.
• Mooring Bitt - A strong pair of iron, steel or wooden posts on a ship's deck, around which ropes or cables are wound and held fast.
• Mooring Buoy - A buoy secured to a permanent anchor sunk deeply into the bottom.
• Mooring Line - A line used to secure a boat to an anchor, dock, or mooring.
• Morse Code - A language of "dots" and "dashes" used to send messages, either sound using radio waves, or light using a searchlight or Aldis lamp.
• Motor - (1) An engine. (2) The act of using an engine to move a boat.
• Motor-sailing - Sailing with the motor on and in gear
• Mount - An attachment point for another object.
• Mouse - Any small collar made with spunyarn or light line to hold something in place.
• Mouse a Hook - The passing of several turns of line across the jaw of a hook to prevent something on the hook, such as an eye or a line, from jumping clear.
• Mudhook - Sailor's slang for anchor.
• Multi-Hull - A vessel formed of two or more hulls. A catamaran has two hulls, and a trimaran has three hulls.
• Mushroom Anchor - A type of anchor with a heavy inverted mushroom shaped head. Mushroom anchors are used to anchor in mud and other soft ground.
• Muster - To assemble passengers and/or crew.
• Mutiny - A forceful resistance to recognized authority. A refusal to obey a legal order of a superior officer is also considered mutiny.

N  [ November ] - [meaning]

• Narrows - Small passages
• National Flag - The flag carried by a ship to show her nationality.
• Natural Gas - Short for compressed natural gas or CNG. A type of compressed gas used as fuel for stoves and heaters. CNG is stored in metal cylinders prior to use. CNG is considered safer than other types of fuel such as propane LPG - because it is lighter than air and may rise into the sky in the event of a leak. Caution should still be used as CNG can collect near the cabin ceiling, potentially causing an explosion.
• Nautical - Having to do with boats, ships, or sailing.
• Nautical Almanac - An annual publication that contains tidal information and information about the position of the sun, moon, planets and stars. This information is used for celestial navigation.
• Nautical Mile - Distance at sea is measured in nautical miles, which are about 6076 feet, 1.15 statute miles or 1852 meters. Nautical miles have the unique property that a minute of latitude is equal to one nautical mile. Measurement of speed is done in knots where one knot equals one nautical mile per hour.
• Naval Architect - One who designs ships.
• Naval Architecture - The art and science of designing vessels.
• Navigable Water - Water of sufficient depth to allow a boat to travel through it.
• Navigation - The art and science of determining the position of a boat and the course needed to safely and efficiently move the boat from place to place.
• Navigation Bridge - The bridge used for taking observations, or directing the handling of the ship.
• Navigation Lights - Required lights on a boat help others determine its course, position and what it is doing. Boats underway should have a red light visible from its port bow, a green light on the starboard bow and a white light at its stern. Other lights are required for vessels under power, fishing, towing, etc.
• Navigation Rules - The maritime regulations governing the movement of vessels in relation to each other, generally called steering and sailing rules. - COLREGS
• Navigational Aid - Any object that a navigator may use to find his position, such as permanent land or sea markers, buoys, radiobeacons, and lighthouses.
• Navigator - The officer on board responsible for the navigation of the ship.
• Neap Tide - The tide with the least variation in water level, occurring when the moon is one quarter and three quarters full. The lowest high tide and the highest low tide occur at neap tide. The opposite is the spring tide.
• Neptune - The Roman god of the sea, associated with Salacia, the goddess of Salt Water.
• Neptune's Sheep - Nickname for waves breaking into foam.
• Net Tonnage - Useful cargo carrying capacity of vessel. The volume of cargo a ship could carry, equal to gross tonnage minus the crew cabins, storerooms and machinery spaces. One ton equals 100 cubic feet.
• Nip - (1) A short turn or twist in a line. (2) The seized part of an eye splice.
• Nipped - Said of a vessel when caught between ice on both sides.
• Nipper - A short length of line, usually braided or marled, used to temporarily bind the anchor cable to the messenger when the anchor is weighed by hand around the capstan.
• No Go Zone - Area into which a boat can not go without tacking.
• No Man's Land - On a square-rigged ship, the area between the after end of the forecastle and the forward end of the booms where lines, blocks, and tackle were stored.
• No Room To Swing a Cat - Describing a small or confined space. Originated from the time when a cat-o'-nine-tails was used to inflict punishment.
• NOAA - National Oceanographic and Atmospheric Administration (U.S.), produces nautical charts and weather forecasts
• Noon Sight - A sighting taken for celestial navigation at noon, when the sun is at its highest point in the sky.
• Noon Watch - The watch or work shift beginning at noon, usually lasting until 4pm or the evening meal.*
• nor'easter - a wind coming from the northeast
• Norman - A pin placed through the head of a rudder to prevent it from being lost.
• North - One of the 4 cardinal compass points. North is the direction toward the North Pole and is at 0° or 360° on a compass card.
• North Pole - The top point of the line about which the earth rotates.
• North Star - Polaris, the North Star, is visible in the northern hemisphere and indicates the direction of north. In the southern hemisphere the Southern Cross is used to find the direction of south.
• North Wind, Northerly Wind - Wind coming from the north.
• Notices to Mariners - Periodic publications containing details of any alterations to charts, to keep them up to date.
• Nun - A kind of navigational buoy
• Nunatak - Isolated rocky peak rising from a sheet of inland ice.

O  [ Oscar ] - [meaning]

• Oakum - A material made of tarred hemp or manila rope fibers, used for caulking seams of decks and sides of a wooden ship in order to make them watertight.
• Oar - A pole with a blade at the end used to row a rowboat. Oars are different than paddles because they have a provision to be secured to the rowboat for rowing, such as an oarlock. The three parts to an oar are: the blade, the part which enters the water; the shaft, the main body of the oar: and the loom, the inboard end on which the rower pulls.
• Oarlock - A device to attach oars to a rowboat, allowing the operator to row rather than paddle the boat.
• Observed Position - A position or fix determined by observing landmarks or other objects to find the position.
• Occulting Lights - A navigational light which turns on and off in a regular pattern, but is on more than it is off, so the period of light is longer than the period of darkness.
• Off and Fair - Order to take off a damaged part of a vessel, to restore it to its proper shape and condition, and to replace it in position.
• Off Soundings - In blue water beyond the 100-fathom line.
• Off the Wind - Sailing with the wind coming from the stern or quarter of the boat.
• Officer - Any of the licensed members of the ship's complement.
• Officer's Mess - Dining room facilities for officers separate from the crew and passenger dining room.
• Official Number - Definition and cross-reference to Tonnage.
• Offing - Seaward, a safe distance from shore; To keep an offing is to keep a safe distance away from the coast because of navigational dangers, fog, or other hazards.
• Offshore - Away from land, toward the water.
• Offshore Wind - Wind blowing from off the shore.
• Offwind - Any point of sailing away from the wind.
• Oil Bag - Used in emergencies, this is a container which allows oil to drip into the sea in heavy weather. An oil slick is produced which prevents waves from breaking over the deck of a boat.
• Oiler - A member of a ship's engineering crew who assisted the chief engineer with lubricating and maintaining the engine.
• Old Salt - A very experienced and/or old sailor
• On a Tack - A sailboat is always on one tack or the other; that is the sail is always on one side or the other.
• On Board - On or in a ship.
• On the Beach - Said of a seaman who has retired from sea service.
• On the Beam - The direction at right angles to a ship's heading or the line of her keel
• On the Bow - To the bow of the boat, forward of the beam.
• On the Hard / On the Ways - Hauled out of the water for repairs or storage
• On the Quarter - A direction of forty-five degrees or less from the stern.
• On the Wind - Sailing close hauled. Sailing toward the wind as much as possible with the wind coming from the bow.
• One o'clock gun - In Edinburgh, Scotland, cannon fired from the Royal Castle in order that the fleet's clocks could be synchronized. Now, a remark to become timely.*
• One-design - Any boat built to certain standards or rules so that is like all others in the same class.
• Onshore - Toward the shore
• OOD - Navy term meaning Officer of the deck.
• Open - A location that is not sheltered from the wind and seas. An open location would not make a good anchorage.
• Ordinary Seaman (OS) - An apprentice Able Seaman, assists AB's, bosun, and officers, keeps facilities clean.
• Orlop - Name given to the lowest deck in a ship.
• Out of Trim - Sails that are not properly arranged for the point of sail that the boat is on. The sails may be luffing or have improper sail shape, or the boat may be heeling too much. These conditions will slow the boat down.
• Out Point - To sail closer to the wind than another boat on the same tack.
• Outboard - (1) Toward or beyond the boat's sides. (2) A detachable engine mounted on a boat's stern.
• Outdrive - A propulsion system for boats with an inboard engine operating an exterior drive, with drive shaft, gears, and propeller; also called stern-drive and inboard/outboard.
• Outer Skin - The outside plating of a vessel.
• Outhaul - A control line that adjusts tension along the foot of the sail, pulling the clew away from the tack; used to maintain proper sail shape.
• Outrigger - A structure which extends outboard beyond the edge of the hull for some special purpose. Some Polynesian canoes use outriggers to support an "ama" or small secondary hull, while fishing boats may use outriggers to suspend lines or nets over the water.
• Overboard - In the water outside of the vessel.
• Overfall - Dangerously steep and breaking seas due to opposing currents and wind in a shallow area.
• Overhang - The area of the bow or stern projecting above and beyond a perpendicular from the water line at stem or stern.
• Overhaul - (1) Repairing or refitting. (2) To overtake another ship at sea. (3) To extend a tackle so that distance between blocks is increased.
• Overhead - Nautical equivalent of ceiling
• Overlap - The distance the bow of a boat is forward of another's stern
• Overstand - Sailing beyond a racing mark or buoy whereby you sail a greater distance
• Overtaking - Passing another vessel.
• Owner's Flag - A boat owner's private pennant.

P  [ PaPa ] - [meaning]

• Pack-Ice - Numbers of large pieces of floating ice that have come together and lie more or less in contact.
• Pad Eye - A loop shaped fitting attached to the deck, spar, boom, etc., used to secure a line or block to some part of the vessel.
• Paddle - A stick with a blade in the end of it used to propel a small boat through the water; The act of using a paddle to propel a boat.
• Paddy's Purchase - Seaman's scornful name for any lead of a rope by which effort is lost or wasted.
• Painter - A line tied to the bow of a small boat for use in towing, securing or tying up
• Pallett - A flat tray, generally made of wood but occasionally of steel, on which goods particularly those in boxes, cartons or bags, can be stacked. Its purpose is to facilitate the movement of such goods, mainly by the use of forklift trucks.
• Palm - A leather tool worn on the hand with a thimble shaped structure on it, and used when sewing canvas or sails.
• PAN PAN - An urgent message used on a radio regarding the safety of people or property. A PAN PAN message is not used when there is an immediate threat to life or property, instead the MAYDAY call is used. PAN PAN situations may develop into MAYDAY situations. As with a MAYDAY, PAN PAN messages have priority on the radio channels and should not be interrupted. In the case of a less urgent safety message, such as a hazard to navigation, the appropriate signal to use is SECURITE.
• Pancake Ice - Small, circular sheets of newly-formed ice that do not impede navigation.
• Panting - Describes the pulsating, in and out movement of ship's plating subjected to variations in water pressure, especially during heavy weather as the ship alternately rises and plunges deep into the water.
• Panting Beam - Beam placed from shipside to shipside to support the shell plating against panting.
• Panting Frames - Frames placed in the forward and after sections of the hull to resist the panting action of the shell plating.
• Panting Stringer - A horizontal stiffener with a breast hook giving added strength against panting.
• Parachute Flare - An emergency signal flare that will float down on a parachute after launch, hopefully improving its visibility.
• Parallax Error - Error that can be introduced when not reading an instrument, such as a compass, directly from its front, due to the separation of the indicator and the scale being read.
• Parallel Rule - Tool used for transferring course and bearing to and from the compass rose on a chart
• Parallels - Latitude lines.
• Parbuckle - A means of hauling up or lowering a cylindrical object.
• Parcel a Rope - To put a narrow piece of canvas around it after it has been wormed, and before it has been served.
• Parcel a Seam - After a seam is caulked, to lay over it a narrow piece of canvas and then pour on hot pitch and tar .
• Parclose - Limber hole of a ship.
• Part - Break; e.g., the line parted under strain
• Parting Strop - Strop inserted between two hawsers, and weaker than the hawsers, so that strop, and not hawsers, will part with any excessive strain.
• Partners - A framework of supporting structures used to support areas where high loads come through openings in the deck, such as the opening in the deck through which the mast passes.
• Passage - A journey from one place to another.
• Passed West - Died. Perhaps derived from the sun setting in the west.
• Passenger Ship - A ship that is authorized to carry more than twelve passengers.
• Patrimonial Sea - The waters adjacent to a country over which it claims jurisdiction. also, Territorial Waters.
• Pay Off - (1) Said of ship's head when it moves away from wind, especially when tacking. (2) To discharge a crew and close Articles of Agreement of a merchant ship.
• Pay Out - To ease out or slacken a line, chain or cable or let it run in a controlled manner.
• Peak - The upper corner of a four sided sail or outer end of the gaff.
• Pedestal - Columnar support for the steering wheel in the cockpit.
• Peggy - Merchant Navy nickname for seaman whose turn of duty it is to keep the mess clean.
• Pelorus - A card marked in degrees and having sightings on it that is used to take bearings relative to the ship, rather than magnetic bearings as taken with a compass.
• Pendant - The line by which a boat is connected to a mooring buoy; a short rope hanging from a spar having at its free end a spliced thimble or a block. Sometimes called "Pennant".
• Pennant - A small tapering flag, which can be used for identification or communication.
• Personal Flotation Device (PFD) - Official terminology for life jacket. When properly used a PFD will support a person in the water. Also called a life jacket, life preserver or life vest.
• Personal Watercraft (PWC) - Small boat similar to and including jetskis
• Petty Officer - Rank intermediate between officer and rating, and in charge of ratings; more or less equivalent to the rank of sergeant.
• Phonetic Alphabet - Alphabet used by the Navy when making sure that a letter is understood; i.e. "BRAVO OSCAR ALPHA TANGO spells BOAT"
• Pier - A loading/landing platform or structure extending at an angle from the shore.
• Pig Stick - A pig stick is a staff that carries a flag or pennant, usually the burgee of the boat owner's yacht club or private signal, above a mast of a sailboat.
• Piggin - Very small wooden pail having one stave prolonged to form a handle. Used as a bailer in a boat.
• Pile - A wood, metal or concrete pole driven into the bottom. Craft may be made fast to a pile; it may be used to support a pier or a float.
• Pile-Driver - (1) A piece of equipment used to drive piles into the ground. (2) Name given to a ship which because of her short length, cannot ride two consecutive waves, and pitches violently into the second.
• Piling - Support, protection for wharves, piers etc.; constructed of piles.
• Pillar - Any steel bar or column, fitted vertically, to support a deck, or any part of a ship's structure. Also called a stanchion.
• Pillow - Block of timber mounted on the deck just inside the bow on which the inner end of the bowsprit was supported.
• Pilot - An individual with specific knowledge of a harbor, canal, river or other waterway, qualified to guide vessels through the region. Some areas require that boats and ships be piloted by a licensed pilot.
• Pilotage - The act carried out by a pilot of assisting the master of a ship in navigation when entering or leaving a port. Sometimes used to define the fee payable for the services of a pilot. Also, the act of navigating a vessel coastwise when land is near and the water is relatively shallow.
• Pilothouse - A compartment on or near the bridge of a ship that contains the steering wheel and other controls, compass, charts, navigating equipment and means of communicating with the engine room and other parts of the ship. Also known as wheelhouse
• Piloting - Navigation by using visible references, the depth of the water, etc.
• Pin End - In sailboat racing, the mark or buoy that signifies one side of the starting line, opposite of the race committee boat.
• Pin Rail - A rail fastened along the inside of the bulwarks of a vessel and pierced to hold belaying pins
• Pinch - To sail too close to the wind so that the sails start to luff.
• Pinching - Sailing too close to the wind
• Pinnace - Formerly, a small, two-masted sailing vessel sometimes with oars.
• Pintle - A tapered metal pin which fastens the rudder to the stern by dropping into gudgeons.
• Pipe - Another name for the bo'sun's whistle.
• Pipe Down - A call on the bo'sun's pipe at night for the hands to turn in, for silence in the messdecks, and for lights to be extinguished. Also a term used by a sailor to another to make them stop talking.
• Piracy - The act of taking a ship on the high seas from those lawfully entitled to it.
• Pitch - (1) The alternate rise and fall of the bow of a vessel proceeding through waves; also called hobby horsing (2) The theoretical distance advanced by a propeller in one revolution. (3) Tar and resin used for caulking between the planks of a wooden vessel.
• Pitchpole - Said of a boat which turns end over end in very rough seas.
• Plain Sailing - Anything that is straightforward and easy.
• Plane, Planing - To gain hydrodynamic lift, causing the boat to lift, rising slightly out of the water so that it is gliding over the water rather than plowing through it, reaching speeds in excess of those normally associated with its waterline length.
• Planing Hull - A type of hull shaped to glide easily across the water at high speed.
• Planing Speed - The speed needed for a boat to begin planing.
• Plank Sheer - On a wooden vessel, the outermost deck plank covering the gunwale. also called Covering Board
• Planking - Wood boards used to cover the ribs, frames, deck or hull of a wooden vessel.
• Plating - Flat steel stock of various thicknesses used in the construction of a ship to form the sides and decks.
• Play - The difference between the diameter of a shaft rod, etc., and that of the hole in which it works.
• Plimsoll Line - The mark stencilled in and painted on a ship's side, designated by a circle and horizontal lines to mark the highest permissible load water lines under different conditions.
• Plot - To mark a course on a chart.
• Plug - (1) A tapered device, usually made from wood or rubber, which can be forced into a hole to prevent water from flowing through it. Plugs should be available to fit every through hull fitting on the boat. (2) The pattern on which the hulls of small craft are molded in fiberglass.
• POB - Persons on board.
• Pod - A group of whales.
• Point - To sail as close as possible to the wind. Some boats can point better than others, sailing closer to the wind.
• Points - [image ] - Division of the circumference of the magnetic compass card into thirty-two points, each of 11° 15'. 
• Points of Sail - The headings of a sailboat in relation to the wind, i.e., upwind, close reach, reach, broad reach, downwind.
• Polaris - The North Star; visible in the northern hemisphere and indicates the direction of north. In the southern hemisphere the Southern Cross is used to find the direction of south.
• Pole - (1) A spar. Such as a pole used to position a sail (e.g., spinnaker pole or whisker pole, which serves the same purpose for a jib). (2) One of the two points around which the earth spins, known as the north and south poles.
• Pontoon - A hollow, watertight tank used to give buoyancy.
• Poop Deck - The short aftermost raised deck of a vessel.
• Poop Rail - A rail surrounding the poop deck.
• Pooped - Hit by a wave over the stern; having a wave wash over the stern of the boat. This can be a very dangerous situation.
• Popple - A short, confused sea.
• Port - (1) The left side of the boat when facing forward; originally called larboard. The opposite of starboard. (2) - A porthole. A window in the side of a boat, usually round or with rounded corners. (3) A harbor.
• Port Tack - Sailing with the wind coming from the port side, with the boom on the starboard side.
• Port of Call - Country, island or territory the vessel visits.
• Porthole - Openings in a ship's hull for ventilation, light and other purposes.
• Poseidon - The Greek god of the sea.
• Position Line or Line of Position - A line drawn on a chart, as a result of a bearing, along which the boat is positioned
• POSH - Port Out, Starboard Home ... Used for Cruising Liners years ago for the "BEST" Cabins. Hence the name!
• Pram - A flat bottomed, blunt nosed dinghy (or small boat).
• Pratique - Certificate given to a ship arriving from a foreign port, by the port's health officer, indicating that there are no cases of disease aboard the ship and the health of all on board is good.
• Preferred Channel Buoy - Also known as a junction buoy. A red and green horizontally striped buoy used in the United States to mark the separation of a channel into two channels. The preferred channel is indicated by the color of the uppermost stripe. Red on top indicates that the preferred channel is to the right as you return.
• Prevailing Winds - The typical winds for a particular region and time of year.
• Preventer - (1) Line and blocks or the boom vang used to keep the boom in place while reaching or running and to prevent an out of control swing during an accidental jibe. (2) Any additional line or wire temporarily rigged to back up any standing rigging in heavy weather.
• Primage - Money paid by shipper to Master of ship for diligence in care of cargo. Not now paid to Master, but added to freight. Amount was usually about 1% of freight.
• Prime Meridian - The meridian from which longitude is measured eastwards or westwards. The longitude of the prime meridian, passing through Greenwich, England, is 0°
• Privateer - A ship owned and armed by a private individual that is empowered by a government to fight with enemy ships and capture enemy shipping in time of war.
• Privileged Vessel - A vessel which, according to the applicable Navigation Rule, has right-of-way. Also known as the "stand on" vessel.
• Prize - An enemy vessel captured at sea by a privateer or a ship of war. The term is also applied to contraband cargo taken from  a merchant ship.
• Procuration - The acting of one person on behalf of another; a document authorizing one person to act on behalf of another.
• Profile Plan - The side elevation of a ship's form.
• Progressive Flooding - When water from a leak passes successively from one compartment to the next, usually in the absence of watertight bulkheads or watertight doors left open.  This is what eventually sank the Titanic.*
• Prop - Slang for propeller.
• Prop Walk - Sideward force created by a spinning propeller.
• Propeller - A rotating device, with two or more blades, that acts as a screw in propelling a vessel. Sometimes called a screw.
• Propogation - Movement of crest of a progressive wave. Can also refer to radio waves.
• Protest - The method by which a racing yacht may object to the actions of a rival on the basis of a breach of the racing rules. A protest committee will hear both sides, and if the protest is upheld, the offending yacht may be penalized.
• Protest Signal - A signal which is hoisted during a sailing race to protest the actions of another (for rules infractions)
• Prow - The bow and forward part of the vessel above the waterline.
• Puff - A sudden burst of wind stronger than the current wind conditions.
• Pulpit - An elevated guardrail set up at the bow of a vessel. When erected at the stern, it is called a pushpit.
• Pumpout - Removing waste from a holding tank.
• Punt - A small flat bottomed boat square at either end.
• Puoy - Spiked pole used for propelling a barge or boat by resting its outboard end on an unyielding object.
• Purchase - Any sort of mechanical device to increase power employed in raising or moving heavy objects. Where two or more blocks are involved in a purchase, it is generally known as a tackle (pronounced "taykle").
• Purse Seine - The small boats used to drag and close the Seine.
• Purser - A ship's officer who is in charge of accounts, especially on a passenger ship.
• Purser's Grin - Hypocritical smile, or sneer.
• Pushpit - A pulpit located on the stern.
• Put About - To change the course of a sailing vessel.
• Put In - To enter a port or harbor

Q  [ Quebec ] - [meaning]

• Q Flag, Quarantine Flag - The Quebec pennant is flown when first entering a country, indicating that the people on the ship are healthy and that the vessel wants permission to visit the country. The flag means "My vessel is healthy and I request free pratique.
• Quadrant - (1) A nautical instrument, on the arc of which is a finely graduated scale showing degrees and minutes, with adjustable reflectors, etc.; used to find the altitude of heavenly bodies, angular distances, etc. (2) On a steering gear, the rudder quadrant is a section of a wheel or sheave fastened to the rudder head.
• Quarantine - A harbor restriction placed on a ship which has an infectious disease on board, or which has arrived from a country where such a disease is prevalent. The crew may not go ashore until the ship is granted pratique.
• Quarter - (1) That portion of the vessel forward of the stern and abaft of the beam. "On the quarter" applies to a bearing 45º abaft the beam. Every boat has a starboard and a port quarter. (2) Mercy shown to captives or enemies, such as giving quarter to the passengers of a seized vessel.*
• Quarter Berth - A bunk which runs under the cockpit
• Quarter Boat - Boat carried at davits on quarter of ship, and kept ready for immediate use when at sea.
• Quarter Spring - Line led forward, from quarter of a vessel, to prevent her from moving astern.
• Quarterdeck - The part of the upper deck which is abaft the mainmast, or in that general location of a ship without one. The quarterdeck was normally reserved for officers.
• Quartering Sea - Winds and waves on a boat's quarter
• Quartermaster - An able-bodied seamen entrusted with the steering of a vessel when entering or leaving a harbor. He is also involved with the use and upkeep of navigational equipment.
• Quarters - Living space for the crew.
• Quay - A solid wharf or structure built of stone along the edge of a harbor used for loading and offloading of cargo, and embarkation and disembarkation of passengers.
• Queen Topsail - Small staysail located between the foremast and mainmast.
• Quick Flashing Light - A navigational aid with a light that flashes about once per second.

R  [ Romeo ] - [meaning]

• Race - (1) A strong, confused tide or current. (2) A competition of skill and seamanship between yachts.
• Rack - The operation of temporarily holding two lines together by seizing.
• Radar - Radio Detection and Ranging. An electronic instrument that uses radio waves to find the distance and bearing of other objects. Used to avoid collisions, particularly in times of poor visibility.
• Radar Arch - An arch to mount the radar, usually at the stern of the boat.
• Radar Reflector - An object designed to increase the radio reflectivity of a boat so that it is more visible on radar. Many small boats are made with fiberglass and other materials that do not reflect radar very well on their own.
• Radiation Fog - Fog over land caused by condensation of vapor in the air above cooler ground.
• Radio - An instrument that uses radio waves to communicate with other vessels. VHF very high frequency - radios are common for marine use, but are limited in range. Single Side Band SSB - radios have longer ranges.
• Radio Beacon - A navigational aid that emits radio waves for navigational purposes. The radio beacon's position is known and the direction of the radio beacon can be determined by using a radio direction finder.
• Radio Direction Finder (RDF) - A navigational instrument which provides a bearing to a radio beacon.
• Radio Operator - An officer who operates and controls the shipboard communication equipment.
• Radiowaves - Invisible waves in the electromagnetic spectrum that are used to communicate (radio) - and navigate (radar).
• Radome - A bun-shaped cover placed over a radar scanner to prevent risk of fouling and to protect it from the weather.
• Raft - A small flat boat, usually inflatable.
• Rafting - (1) When two or more boats tie up alongside each other. (2) Overlapping of edges of two ice-floes, so that one floe is partly supported by the other.
• Rail - (1) The edge where the deck joins the hull; top edge of bulwarks. (2) The railing around the deck.
• Rake - The inclination of a vessel's mast from its vertical position. The rake may be either forward or aft, and can be deliberately induced (by adjustment of the standing rigging) to flatten sails, balance steering, etc. Normally slightly aft. The term can also be used to describe the degree of overhang of a vessel's bow and stern.
• Ram - A strengthened or armored projection from the bow of a warship for the purpose of disabling or sinking an enemy ship by ramming her.
• Range - (1) Sighting two objects in a line to indicate a course to be steered (2) The distance a boat can travel using the fuel stored aboard.
• Rap Full - As close to the wind as possible, with all sails full, and no wrinkles in them.
• Rate - The rank held by a naval seaman.
• Rating - (1) Term describing the status of seamen, corresponding to rank in the case of officers. (2) A method of measuring a yacht's expected performance relative to another yacht while racing. Over the years many formulas have been experimented with, in order to enable diverse yachts to race competitively against each using a handicap based upon the rating.
• Ratlines - Small lines tied between the shrouds that form steps to function as a ladder to climb the rigging.
• Rattle Down - The operation of securing the ratlines to the shrouds.
• RDF - Radio Direction Finder. The RDF is used with a radio beacon to find a radio bearing to help determine the vessel's position.
• Reach - (1) A point of sail between close-hauled and a run, with the wind coming from abeam. (2) A distance, or fetch. (3) Straight stretch of water between two bends in a river or channel.
• Reaching - Any point of sail with the wind coming from the side of the boat. If the wind is coming from directly over the side, it is a beam reach. If the wind is coming from forward of abeam it is a close reach. If the wind is coming from over the quarter, it is called a broad reach.
• Ready About - An expression used to the crew to indicate that the boat is about to tack.
• Reciprocal - A bearing 180° from the other. A direction directly opposite the original direction.
• Reciprocating Engine - A form of steam engine where a piston moves back and forth inside a cylinder, transmitting its motion to a driving shaft by a connecting rod and crank.
• Reckoning - The record of courses steered and distances traveled since the time a ship's position was last fixed by shore or astronomical observations.
• Reduction Gears - The gears that reduce engine speed to propeller speed.
• Reef - (1) The rolled up part of a sail, tied with the reef lines, that is used to reduce sail area for heavy winds; To reduce the sail area. (2) A group of rocks or coral generally at a depth shallow enough to present a hazard to navigation.
• Reef Cringles - Reinforced cringles or thimbles in the sail designed to hold the reefing lines when reefing the sail.
• Reef Knot - [image] - Also known as the square knot, it is formed by two half hitches in which the ends always fall in line with the outer parts. This knot is used to loosely tie lines around the bundles of sail that are not in use after reefing.
• Reef Lines - Short pieces of line fastened to the sail at reef points, used for tying a reef to reduce sail area. The reef line will pass through reef cringles, which will become the new tack and clew of the reefed sail.
• Reef Points - Short lengths of line attached to the sail used to tie the extra sail out of the way when reefing.
• Reefer - (1) Slang for refrigerator. (2) Refrigerator ship; a vessel designed to carry goods requiring refrigeration, such as meat and fruit.
• Reefing - The operation of reducing a sail by taking in one or more of the reefs.
• Reeve - To pass or lead a line through a block or other object. When the end of a line is passed through anything, it is said to be "rove" through it.
• Refit - Removal of worn or damaged gear and the fitting of new gear in replacement.
• Registry - The country in which the vessel is registered.
• Relative Bearing - Direction or bearing of an object relative to a boat's heading.
• Relieve the watch - Rested crewmembers take over the operation of the vessel from those who have worked a turn.  Also, "Relief" is the person who will take your duties.*
• Render - (1) The action of a line as it passes over the sheave of a block. (2) The act of easing away gently.
• Repel Boarders - An order announced for the ship's company to arm themselves to prevent boarding of their ship. *
• Repositioning - Vessel moves to a new area for a new season.
• Reserve Buoyancy - The lifting power. It may be measured by the volume of a watertight hull above the load water line.
• Return Port - The proper return port of a discharged seaman.
• Revenue Cutter - A single masted cutter built expressly for the prevention of smuggling and the enforcement of customs regulations.
• Reverse Sheer - When the sheer curves down towards the bow and stern.
• Rhumb Line - A straight line compass course between two points. A line on the earth's surface which intersects all meridians at the same angle.
• Ribband - Strips of material temporarily holding parts of a ship in position.
• Ribs - The frames or timbers of a ship as they rise from the keel to form the shape of the hull.
• Ride To - Lie at anchor
• Riding Light - An all around white light displayed at night by a ship when she is anchored.
• Rig - The way a boats spars and sails are arranged. To rig a vessel is to fit her with masts, spars, sails and running and standing rigging; term is also used to mean the setting up a device, e.g., to rig a lifeline, a tackle, etc
• Rigger - One whose occupation is to rig or unrig vessels.
• Rigging - A general term applying to all the lines, stays and shrouds necessary for spars and sails. The standing rigging is the mast, shrouds and stays, while running rigging refers to halyards and sheets that control the sails
• Right Ascension - Right Ascension of a celestial body is the arc of the equinoctial between Aries and the meridian of the object, always reckoning eastward from Aries.
• Right of Way - The right to maintain a course according to the Rules of Navigation. When two boats are on intersecting courses, one is the "stand-on" vessel (has "right of way" and must hold its course steady) so the other "give-way" vessel may steer clear.
• Righting Arm - The theoretical measurement of force by which a heeled vessel is returned to upright by virtue of its displacement and gravity, expressed in foot/pounds, etc.*
• Rip Tide - The rip tide is not a tide, it is a current. When waves hit the beach they hit at an angle and push water ahead of them. This water forms a current that flows parallel to the shore, called the longshore current. When the shape of the beach changes, or its direction (as in from North-South to Northeast-Southwest) the speed of the current changes. Locally this can cause more water to flow into an area than can flow out, and water will pile up. This is much like a traffic jam for the currents. However, the water, which is trapped next to the shore, cannot get out because of the longshore current. Eventually, so much water will pile up that it can break through the longshore current in a small area. The large amount of water rushing through a small break causes a strong current in a small area that flows perpendicular (away) from the shore. This is the rip tide.
• Rips - Short, steep waves caused by the meeting of currents.
• Rivet - A metal pin by which the plating and other parts of iron and steel vessels are joined. Rivets are known by their heads, such as: Flush, pan, snap, plug, tap, countersunk, mushroom, and swollen neck.
• Roach - A curve out from the aft edge (leech) of a sail. Battens are sometimes used to help support and stiffen the roach.
• Rocker - The upward curvature of the keel towards the bow and stern.
• Rode - The anchor line, cable or chain that connect the anchor to the boat.
• Rogue Knot - Seaman's name for a reef knot tied upside down. also called a "granny" knot.
• Roll - The alternating motion of a boat, leaning alternately to port and starboard; the motion of a boat about its fore-and-aft axis.
• Roller Furling - A method of storing a sail, e.g., by rolling the jib around the headstay.
• Roller Reefing - A system of reefing a sail by partially furling it. Roller furling systems are not necessarily designed to support roller reefing.
• Rolling Hitch - [image] - A hitch used for bending a line to a spar, which if tied properly, won't slip. The end of the line is passed around the spar and then passed a second time around so it rides over the standing part. Then it is carried across and up through the bight.
• Rooming - The navigable water to leeward of a vessel.
• Rope - When rope comes aboard a vessel and is put to use, it is called line, although some still call it rope if it is over one inch in diameter. A coil of rope that is not designated for any particular use.
• Rope Yarn Sunday - A time during working hours granted by the Captain for the off-watch to attend to the condition of their clothing and other personal items, usually an easier day granted as a break from hard work.*
• Rose Box - The strainer at the end of the suction pipe of a bilge pump which prevents solid material in the bilges from being sucked into the pump and choking it. Also known as a strum box.
• Round - A verb with a variety of meanings. To round in is to haul in quickly; to round up is to bring a sailing vessel head into the wind; to round down a tackle is to overhaul it; to round a mark is to pass a racing mark.
• Round Turn - One complete turn of the line around a cleat, spar or another line.
• Round Turn and Two Half Hitches - [image] - A knot widely used when making a boat fast to a post or bollard.
• Rouse Out - Turning out all hands on board ship in the morning, or calling the watch for duty on deck.
• Row - A method of moving a boat with oars. The person rowing the boat faces backwards, bringing the blade of the oars out of the water and toward the bow of the boat. They then pull the oars through the water toward the stern of the boat, moving the boat forward.
• Rowboat - A small boat designed to be rowed by use of its oars. Some dinghies are rowboats.
• Royal - On a square-rigged ship, a light weather sail set next above the topgallant-sail in fair weather.
• Rubrail - Also rubbing strake or rub strake. An applied or thickened member at the rail, running the length of the boat; serves to protect the hull when alongside a pier or another boat.
• Rudder - A board-shaped swinging vane, controlled by a tiller or wheel, and attached to the rudderpost or stern for steering and maneuvering a vessel.
• Rudder Angle Indicator - Piloting instrument showing the number of degrees to port or starboard at which the rudder(s) currently is/are positioned.*
• Rudder Post - The post that the rudder is attached to. The wheel or tiller is connected to the rudder post.
• Rules of the Road - The rules concerning which vessel has the right of way if there is a possibility of collision between two or more boats; written to prevent accidents and collisions; includes right of way, lights, pennants, and whistle signals
• Rummage - Originally meant "to stow cargo". Now, means "to search a ship carefully and thoroughly".
• Run - (1) Sailing away from the wind with the sails let out all the way; going with the wind, downwind sailing (2) To allow a line to feed freely. (3) The shape of the afterpart of the underbody of a ship in relation to the resistance it creates going through the water.
• Run Aground - To take a boat into water that is too shallow for it to float in, i.e: the bottom of the boat is resting on the ground.
• Run Out - To put out a mooring, hawser or line from a ship to a point of attachment outside her.
• Running - Sailing in the same direction as the wind with the wind coming from the stern.
• Running Backstay, Runners - Adjustable stays used to support and control tension on the mast when the wind is from abaft the beam; temporary backstays used to stabilize the mast and prevent undue flexing due to the pumping action of the sea.
• Running Bowline - [image ] - A type of knot that tightens under load. It is formed by running the standing line through the loop formed in a regular bowline, or by tying around a bight in the line.
• Running Fix - A fix taken by taking bearings of a single object over a period of time. By using the vessel's known course and speed, the location of the vessel can be found.
• Running Lights - Lights required to be shown on boats underway between sunset and sunrise; they tell other vessels not only where you are, but what you are doing
• Running Rigging - All control lines such as sheets and halyards used to control the sails

S  [ Sierra ] - [meaning]

• S.S. - Prefix before a ship's name to indicate that she is a steamship.
• Sacrificial Anode - A metal, usually zinc in salt water or aluminum in fresh, affixed to the outside of a vessel intended to erode by galvanic electric current (caused by the immersion of dissimilar metals in water, much like a battery) so that useful metal parts are not corroded.*
• Saddle - A block of wood or a bracket attached to a spar to support another spar attached to it.
• Safety Harness - A device worn around a person's body that can be tethered to jack lines to help prevent a person from falling overboard.
• Safety Pin - (1) Any pin that is used to prevent a fitting from falling open. (2) A pin used to keep the anchor attached to its anchor roller when not in use.
• Sagged - When from some cause a vessel's form is so altered that the ends of the keel are much above the level of its midship portion, it is said to be "sagged." The opposite of hogged.
• Sail - A large piece of fabric designed to be hoisted on the spars of a sailboat in such a manner as to catch the wind and propel the boat.
• Sail Shape - The shape of a sail, with regard to its efficiency. Controls such as the cunningham, boom vang, outhaul, traveler, halyards, leech line, sheets, and the bend of the mainmast all can affect sail shape. Also sail trim.
• Sail Track - A slot into which the bolt rope or lugs in the luff of the sail are inserted to attach the sail.
• Sail Trim - The positioning and shape of the sails to the wind; To sheet in or out the sails for the most optimal performance and speed
• Sailboat - A boat which uses the wind as its primary means of propulsion.
• Sailcloth - A fabric, usually synthetic, used to make sails.
• Sailing By The Lee - Sailing on a run with the wind coming over the stern from the same side as the boom (danger of jibing).
• Sailing Directions - Publications that describe features of particular sailing areas, such as hazards, anchorages, etc.
• Sailing Ice - Small masses of drift ice with waterways in which a vessel can sail.
• Sailing Rig - The equipment used to sail a boat, including sails, booms and gaffs, lines and blocks, etc.
• Sailor - Man or boy employed in sailing deep-water craft. Word is sometimes loosely used to include men who go to sea. Used officially to denote a seaman serving on deck.
• St. Elmo's Fire - An electrical discharge caused by certain atmospheric conditions, which takes place around the rigging. Known by many other names, it was regarded by many superstitious seamen as a favorable omen, foretelling the end of stormy weather. And others believed they would die within 24 hours if light from this phenomenon fell upon their face.
• Sallying - Rolling a vessel, that is slightly ice-bound, so as to break the surface ice around her. May sometimes be done when a vessel is lightly aground, but not ice-bound. Can be accomplished by having most of the crew run side-to-side.
• Salon - Also saloon; the main social cabin of a boat
• Salvage - Recovery and reclamation of damaged, discarded or abandoned material, ships, craft and floating equipment for reuse, repair, re-fabrication or scrapping. Also the property which has been recovered from a wrecked vessel, or the recovery of the vessel herself.
• Sampson Post - A strong vertical post used to attach lines for towing or mooring.
• Sargasso Sea - An area of the North Atlantic east of the Bahamas where a powerful eddy in the water causes Sargasso weed to collect in vast quantities and float on the surface.
• Scandalize - A method of reducing sail in a fore-and-aft rig by hauling up the tack and lowering the peak of a sail. It was used by older sailing trawlers to reduce speed through the water while operating a trawl. Also the yards in a square-rigged ship are said to be scandalized when they are not set square to the masts after the ship has anchored. Scandalizing the yards of a ship was a sign of mourning for a death on board.
• Scantlings - The dimensions of all parts which go into the construction of a ship's hull.
• Scarf or Scarph - The joining of two timbers by beveling the edges so the same thickness is maintained throughout the length of the joint.
• Schooner - A fore-and-aft rigged sailboat with two or more masts. The aft mast is the same size or larger than the forward ones.
• Scope - The ratio of the length of an anchor line, from a vessel's bow to the anchor, to the depth of the water.
• Scow - A boat with a flat bottom and square ends.
• Screw - A boat's propeller.
• Scrimshaw - A sailor's carving or etching on bones, teeth, tusks or shells.
• Scuba - Self Contained underwater Breathing Apparatus - see Aqualung.
• Scud - To run before a gale with reduced sail or bare poles. This could be dangerous, with the possibility of being pooped.
• Scull - Moving the rudder, or a single oar over the stern, back and forth in an attempt to move the boat forward
• Scupper - An opening in a deck, cockpit, toe-rail or gunwale to allow water to run off the deck and drain back into the sea.
• Scurvy - A disease caused by lack of Vitamin C historically common to seaman, because of the difficulty in preserving fresh fruits and vegetables.
• Scuttle - (1) To deliberately sink a ship. (2) A small hatch; a round window in the side or deck of a boat that may be opened to admit light and air, and closed tightly when required.
• Scuttlebutt - Gossip, usually about other people or events. The term scuttlebutt evolved from the name of a keg containing water and alcohol that sailors used to gather about before meals.
• Sea - (1) A body of salt water. A very large body of fresh water. (2) The condition of the water around a boat. Heavy seas for example. 
• Sea Anchor - A drogue or drag device to slow down a boat, hold its bow into the sea in heavy weather, and reduce the boat's drift downwind.
• Sea Battery - Assault upon a seaman, by Master, while at sea.
• Sea Boat - Ship's boat kept ready for immediate lowering while at sea. When used for life-saving, it was called an "accident boat" or  lifeboat.
• Sea Breeze - Cool air pulled ashore by rising thermal air currents caused by the air inland rising as the land heats up
• Sea Buoy - The last buoy as a boat heads to sea.
• Sea Captain - Master of a sea-going vessel. Certificated officer competent and qualified to be master of a sea-going vessel.
• Sea Chest - The cavity inside a Sea Suction from which pumps raw seawater, often for cooling purposes.
• Sea Suction - Underwater opening in a ship's hull. May be several feet in diameter. Usually fitted with a grating to prevent the entry of large, unwanted objects.
• Sea Dog - Old and experienced seaman.
• Sea Kindly - A boat that is comfortable in rough weather.
• Sea Lawyer - Nautical name for an argumentative person.
• Sea Level - The average level of the oceans, used when finding water depths or land elevations.
• Sea Room - A safe distance away from a shore, jetty, another boat, or other hazards.
• Sea Smoke - Vapour rising like steam or smoke from the sea caused by very cold air blowing over it.
• Sea Trials - A series of trials conducted by the builders to determine if the vessel has met the specifications and is operating properly.
• Seabag - A soft, cylindrical fabric bag for clothes and personal possessions
• Seacock - A through hull valve, a shut off on a plumbing or drain pipe between the vessel and the sea
• Seafarer - One who earns his living by service at sea.
• Seam - On vessels constructed of wood, the narrow gap between the planks which form the decks and sides and were caulked to make them watertight. Since wood swells when it's in contact with water, a narrow seam is necessary to allow for the expansion.
• Seamanlike - In a manner, or fashion, befitting a seaman.
• Seamanship - All the arts and skills of boat handling, ranging from maintenance and repairs to piloting, sail handling, marlinespike work, rigging, and all aspects of a boats operation.
• Seaworthiness - Statement on the condition of the vessel. The sufficiency of a vessel in materials, construction, equipment, crew and outfit for the trade in which it is employed. Any sort of disrepair to the vessel by which the cargo may suffer, overloading, untrained officers, etc., may constitute a vessel unseaworthy.
• Second Assistant Engineer - On steam vessels has responsibility for the boilers, on diesels, the evaporators and the auxiliary equipment.
• Second Greaser - Old nickname for a second mate.
• Second Mate - Ships navigation officer. Keeps charts (maps) up to date and monitors navigation equipment on bridge.
• Secondary Port - A port that is not directly listed in the tide tables but for which information is available as a difference from a nearby standard port.
• Section - A drawing representing the internal parts of a vessel as if she had been cut straight through, either longitudinally or athwartships. It shows the positions of the frames and their exact curvature in relation to the hull shape.
• Sector - An arc of a circle in which certain types of navigational lights known as sector lights are visible.
• Secure - To make fast; to make safe and shipshape. To stow an object or tie it in place.
• Seiche - Short period oscillation in level of enclosed, or partly enclosed, area of water when not due to the action of tide-raising forces.
• Seine - The large nets used for fishing they have weights on one edge and floats on the other. They can be closed to contain the fish.
• Seize - (1) To bind a line with marline, cord, twine, wire, or other "small stuff" to prevent accidental opening or unraveling (2) To freeze up, as a valve.
• Seized - Bound together.
• Seizing - The cord, twine or other small stuff which is used to seize line.
• Self-bailing Cockpit - A watertight cockpit with scuppers, drains, or bailers that remove water.
• Semaphore - A method of signaling and communicating using two flags held in position by the signaler, the positions of the flags denoting the meaning.
• Separation Zone - A region drawn on a chart to separate two lanes that have shipping vessels moving in opposite directions.
• Serve - To wind small line around a rope to protect it. Rope is wormed, parcelled and served to protect it from water which could rot it, or from chafing
• Serving Mallet - A mallet used for passing serving around a line.
• Set - (1) To raise a sail. (2) A term applied to sails in relation to their angle with the wind; e.g., the set of the jib. (3) The direction the current is flowing (4) Movement of a ship, due to current or tide, not necessarily in the direction in which the ship is heading. (5) A ship sets sail when she departs on a voyage, whether sails are used or not. (6) An anchor is set when it has gripped the bottom and holds without dragging.
• Sewed - Said of a vessel when water level has fallen from the level at which she would float, so she would be aground and need to wait for the next tide before re-floating. Also said of the water that has receded and caused a vessel to go aground.
• Sextant - A navigational instrument used to measure the altitude of celestial bodies
• Shackle - A U-shaped fitting closed with a pin across the open ends, the pin sometimes being threaded at one end and sometimes held in place with a cotter pin, and used to secure sails to lines or fittings, lines to fittings, fittings to fittings, anchors to chain, etc.
• Shaft - A cylinder used to carry rotating machine parts, such as pulleys and gears, to transmit power or motion; such as a propeller shaft.
• Shaft Alley - The narrow compartment ending at the place where the shafts go through the packing glands at the skin of the vessel. ¹
• Shaft Log - A heavy longitudinal timber placed over the keel in a ship's stern through which the propeller shaft passes.
• Shaft Strut - A term applied to a bracket supporting the after end of the propeller shaft and the propeller.
• Shake - (1) A longitudinal crack in a mast or other spar. (2) The shivers of a sail when sailing too close to the wind. (3) As a verb, to let it out.
• Shake Out - To remove a reef from a sail and hoist the sail aloft
• Shallop - (1) Small boat for one or two rowers. (2) Small fishing vessel with foresail, boom mainsail, and mizzen trysail.
• Shank - The main shaft of an anchor which connects the arms to the anchor ring.
• Shanty - see Chanty.
• Sharp Up - Said of a square-rigged ship with her sails trimmed as close to the wind as possible.
• Sharpen Up - To come up more into the wind
• She - All boats are referred to as female. She is at anchor. Her sails are set. She is beautiful.
• Shear Pin - A safety device, used to fasten a propeller to its shaft; it breaks when the propeller hits a solid object, thus preventing further damage.
• Sheathing - A covering to protect the bottom of a boat.
• Sheave - The revolving wheel with grooved edge mounted in a block to guide the line or cable (pronounced shiv)
• Sheepshank - [image] - A knot used to temporarily shorten a line.
• Sheer - The straight or curved line of the deck line; curvature of the lines of a vessel toward the bow and stern.
• Sheer Plan - A vertical longitudinal center line section of a vessel.
• Sheer Strake - The topmost planking in the sides, next below the gunwale, often thicker than other planking.
• Sheet - A line that controls the angle of the sail in its relation to the wind; attached to the clew of a sail to adjust its trim (make the sail the proper shape to catch the wind).
• Sheet Bend - [image] - A hitch used to join two ropes. It can be used between lines of different diameters.
• Sheet In - Pull the sail in by pulling on the sheet.
• Sheet Out - Let the sail out by easing the sheet.
• Shelf-Ice - Land ice, either afloat or on ground, that is composed of layers of sow that have become firm but have not turned to glacier ice.
• Shell - (1) The outside plating of a ship from stem to stern. (2) The outer casing of a block inside which the sheave revolves.
• Shellback - An old and experienced seaman.
• Shift - A change in the wind direction.
• Shift Colors - Navy term meaning to change the arrangement of the colors (the national flag) upon getting under way or coming to moorings.
• Shifting - This refers to movements or changing positions of cargo from one place to another. This can easily endanger the seaworthiness or cargo-worthiness of the ship.
• Shifting Boards - Temporarily placed longitudinal bulkheads used to prevent bulk cargo from shifting.
• Ship - (1) Generic name for a large sea-going vessel. (2) To take an object aboard, such as cargo, or water. (3) To put items such as oars on the boat when not in use.
• Ship's Agent or Broker - A person or firm who transacts all business in a port on behalf of shipowners or charterers. Also called shipping agent; agent.
• Ship's Articles - A written agreement between the master of a ship and the crew concerning the terms of their employment.
• Ship's Bells - The watches aboard ship change at 4, 8, and 12 around the clock. A watch lasts four hours and at each half hour during the watch, a bell is struck. For instance, at 12:30 a.m. there is one bell for the first half hour after midnight; at 1:00 a.m. there are two bells for the two half hours, and at 4:00 a.m. eight bells for the eight half hours passed. This sequence is repeated for each new watch. See Bells
• Ship's Chairman (Shop Steward) - In charge of union business for unlicensed personnel. Handles grievances.
• Ship's Company - All those employed to work on board the vessel.
• Ship's Log - A book with a record of every occurrence and incident concerning the ship.
• Ship's Port Agent - A business firm which sells its services to organizations which operate vessels
• Ship's Stability - The seaworthiness of a ship regarding the centrifugal force which enables her to remain upright.
• Shipmaster - A person in command of a ship. A person certified as competent to command a ship. A master mariner.
• Shipping Lane - Path through open water used for commercial vessel passage and so noted on chart
• Shipwright - A ship builder, or one who works about a ship. Does wood carpentry on the ship and keeps ships faired. Builds launching ways and launches ship.
• Shiver My Timbers! - An expression of surprise or unbelief, as when a ship strikes a rock or shoal so hard that her timbers shiver.
• Shoal - (1) Shallow water. (2) An underwater sand bar or hill that has its top near the surface.
• Shoe - (1) A false keel. (2) The projection of the keel abaft the stern frame where the spindle of the rudder rests.
• Shoot - (1) A navigator shoots the sun by using a sextant to measure its altitude. (2) A sailing vessel shoots when she forges ahead to windward with her sails luffing.
• Shoot Ahead - To move ahead swiftly. To move ahead of another vessel quickly when underway.
• Shore - (1) The land in general, but usually refers to that part adjacent to the water. (2) A timber used in damage control to brace bulkheads and decks. (3) One of the many wooden props by which the ribs or frames of a vessel are externally supported while building, or by which the vessel is held upright on the ways.
• Shoring - The act of supporting anything by propping or shoring it up.
• Short Sea - When the distance between the wave crests is less than normal.
• Short Stay - Said of a vessel's anchor, or cable when the amount of cable out is not more than one-and-a-half times the depth of water.
• Short Ton - 2,000 pounds.
• Short Splice - To permanently join two pieces of rope. It will not pass through a block since it increases the diameter
• Shove Off - To leave; to push a boat away from a pier or vessel's side.
• Shroud - Part of the standing rigging that helps to support the mast laterally by running from the top of the mast to the side of the boat. Sailboats usually have one or more shrouds on each side of the mast. Some people call them side stays
• Side Lights - Green and red lights on the starboard and port sides of the boat required for navigation at night. Each light is supposed to be visible through an arc of 112.5°, beginning from directly ahead of the boat to a point 22.5° aft of the beam.
• Sidereal Hour Angle - The westerly distance in an arc from Aries, measured as an angle at the pole or as the intercepted arc of the equinoctial between the hour angle of Aries and the hour angle of the body.
• Sideslip - The tendency of a boat to move sideways in the water instead of along its heading due to the motion of currents or currents.
• Sight - A nautical astronomical observation of the sun, moon, or a star, by which means a vessel's position can be determined. The sight was taken with a sextant at a specific time, determined by a chronometer.
• Sighting - Observing with the eye. Applied to a document, means examining and signing as evidence of satisfaction as to its authenticity.
• Sighting the Bottom - Drydocking, beaching, or careening a vessel and carefully examining the bottom with a view to ascertaining any damage it may have.
• Signed Under Protest - Words incorporated when signing under duress and not concurring entirely with import of document signed, and after stating grounds of non-concurrence.
• Single Sideband - A type of radio carried on a boat to transmit long distances.
• Single Up - To cast off all but one remaining line.
• Sirens - Mythical sea nymphs who charmed men with their melodious voices. Enchanted, the men would stop all work to listen and they would ultimately die of starvation because of their inability to sail any further.
• Sister Ships - Ships built on the same design.
• Sixteen Bells - Eight double strokes on ship's bell; customarily struck at midnight when new year commences.
• Skeg - An extension of the keel for protection of propeller and rudder.
• Skeleton (Of a vessel) - The hull without the outside and inside plating.
• Skiff - Technically, a flat-bottomed boat, but often used to name any small boat for rowing, sculling, or fitted with an outboard motor
• Skin - The plating of a ship.
• Skipper - The captain or master of a ship.
• Skipper's Daughters - An old name for high waves when they break with a white crest.
• Skylarking - gazing uselessly about, usually at the sky.*
• Skylight - A framing of metal fitted over an opening in a deck, with glass or plexiglass inserted for the admission of light into a cabin, engine room, etc.
• Skysail - On a square-rigged ship, a light weather sail set next above the royal in fair weather.
• Skyscraper - On a square-rigged ship, a small triangular sail set above the skysail in fair weather. A square version is called a Moonraker.
• Slab Reefing - Reduces the area of the mainsail by partially lowering the sail and re-securing the new foot by tying it to the boom with points, or light lines attached to the sail. Also called  points reefing and jiffy reefing. 
• Slack - Not fastened; loose. Also, to loosen or ease off.
• Slack Away - To let out a line
• Slack Tide or Slack Water - A short period at the turn of the tide. The time between flood and ebb tides when there is no current flow.
• Slam Dunk - In sailboat racing, a tactical maneuver to lock in a competitor by tacking on them in close proximity so they can not tack from under your boat and they start to lose speed due to your sails blocking their sails.
• Slatting - Flapping (of sails)
• Sliding Ways - A structure of heavy timbers placed between ground ways and cradle to support the ship during launching.
• Slings - In general the line, web straps, cable or chains attached to a heavy object to lift it.
• Slip - (1) To let go purposely. (2) Where a vessel ties up, as the space between piers.
• Slippery Hitch - A bend or hitch used to attach a line to a ring or spar so that by pulling the end of the line, the hitch will come free. This is done by passing a bight of the line under the other part so that when strain is applied the bight is jammed. A pull on the end of the bight clears it.
• Slob - Loose and broken ice in bays, or along exposed edges of floes.
• Sloop - A single masted vessel with fore and aft rigged sails.
• Slop Chest - Chest, or compartment, in which is stowed clothing for issue to crew.
• Slop Room - Compartment in which clothing for issue to crew is stowed.
• Slops - Crew store managed by crew members offering everything from snacks to toiletries. Originally the name given to clothing that was issued to seamen.
• Slot - The opening between the jib and the mainsail. Wind passing through this opening increases the pressure difference across the sides of the mainsail, helping to move the boat forward.
• Smartly - A rate of action. In this case, quickly.
• Smelling the Ground - Said of a vessel when her keel is close to the bottom and all but touching it.
• Smuggle - The operation of secretly bringing goods into a country to avoid paying duty on the goods. Also applies to illicit goods.
• Snap Hook - A metal fitting with an arm that uses a spring to close automatically when connected to another object.
• Snatch Block - [image] - A block with a single sheave which is hinged and opens on the side so that the bight of a line can be led into the block and closed without running the whole length through
• Snorter - A very high wind. Also called "Snotter"
• Snub - To stop the running out of a line by taking a turn around a cleat, piling, etc.; to suddenly stop or secure a line. A ship with too much way can be snubbed by letting an anchor go.
• Snubber - A spring line tied from the boat to chain rode, usually near the water's surface. It helps disperse tension forces. It also prevents damage to the boat by ground tackle and can help in the retrieval of the ground tackle in heavy weather.
• Snubber Line - Line used for checking a vessel's way when warping her into a dock or basin.
• Soft Tack - Fresh bread.
• SOG - Speed Over Ground, speed relative to bottom.
• SOLAS - Safety of Life at Sea Convention
• Soldiers Wind - A wind which blows on the beam thus requiring no tacking or trimming of the sails. It will take a sailing vessel somewhere without requiring much nautical ability.
• Sole - Cabin or salon deck or floor; the inside deck of the ship
• Son of a Gun - Seaman who was born aboard a warship. As this was once considered to be one of the essentials of the perfect seaman, it has long been a complimentary term.
• Sonar - SOnar Navigation and Ranging - A device which emits pulses of high frequency sound which are reflected by any solid object they encounter. The time from the emission of the pulse and the arrival of its returning echo is measured, giving a range to the object. This is the basis of all depth sounders, measuring the depth of water under the ship.
• SOS - A distress call made by a vessel requiring assistance. These three letters were chosen because they were easy to make and read using Morse Code. Some believe the letters meant "Save Our Ship" or "Save Our Souls".
• sou'wester - A wind coming from the southwest
• Sound - (1) To measure water depth or the depth of liquid in a tank (2) Signals required by navigation rules describing the type of vessels and their activities during times of fog.
• Sounding(s) - Depth measured; the number indicating depth on a chart; the process of measuring fuel or water in ships' tanks. A ship is thought to be "in soundings" when she is inside the 100 fathom line, and "off soundings" when she is outside that line.
• South - One of the 4 cardinal compass points. South is the direction toward the South Pole and is at 180° on a compass card.
• South Wind, Southerly Wind - Wind coming from the south.
• Spanker - An additional sail hoisted on the mizzen mast to take advantage of a following wind.
• Spanking - Applied to a wind, or movement of a vessel, to denote brisk and lively.
• Spar - A pole used as part of the sailboat rigging, such as masts, booms, gaffs, yards, etc. A vertical spar is a mast.
• Spar Buoy - A tall buoy used as a navigational aid.
• Spherical Buoy - A ball shaped buoy marking a navigational hazard.
• Spider - An outrigger used to hold a block clear of a mast or of the ship's side.
• Spile Hole - Small hole bored in cask or barrel to allow air to enter when emptying.
• Spile Pin - The recessed pin used to secure a lugless anchor shackle and also the securing pin in a Kentor lugless joining shackle for anchor cables.
• Spill - To spill the sails is to take the wind out of the sails, either by heading up into the wind, or by easing the sheets to the point where the sails can hold no wind.
• Spill Pipe - An overflow pipe.
• Spindle Buoy - A tall cone shaped navigational buoy.
• Spindrift - Finely-divided water swept from crest of waves by strong winds.
• Spinnaker - A large balloon shaped lightweight sail used when running or reaching. Spinnakers are made of cloth very similar to that used for parachutes, which is why you may also hear them called chutes, or kites.
• Spinnaker Halyard - A halyard used to raise the spinnaker.
• Spinnaker Pole Lift - A line running from near the top of the mast, used to hold the spinnaker pole in place.
• Spit - A small projection of land.
• Spitfire Jib - A small storm jib made of very heavy cloth.
• Splashboard - A raised portion of the hull forward of the cockpit intended to prevent water entering.
• Splice - To join two lines together by interweaving and tucking their strands over and under each other in various manners. A strong way of joining lines without the use of knots.
• Splice the Main Brace - A traditional term in the British Navy for serving out an additional tot of rum or grog to a ship's crew. In sailing ship days the main brace was spliced (in terms of drink) in very bad weather or after a period of severe exertion by the crew.
• Spliced - To get spliced is slang for getting married. A splice joins two lines together permanently.
• Spline - A flexible strip used for fairing lines.
• Split Tacks - To take the opposite tack when sailing to windward with another yacht.
• Spoke - In a wheel, such as a steering wheel, a spoke is a rod that extends from the hub outwards to the rim.
• Sponson - 1) Any of several structures that project from the side of a boat or ship, especially a gun platform. 2) Appendages added to the side of a vessel, such as a canoe or kayak, to aid in stability. 3) A pontoon-like hull, or portion of a hull, that provides lift. A three-point hydroplane has two sponsons, one each side of the main hull.
• Spooning - Running directly before wind and sea.
• Spray - Water blown, or thrown, into the air in particles.
• Spreader(s) - Small struts or spars extending toward the sides from one or more places along the mast. The shrouds cross the end of the spreaders, enabling the shrouds to better support the mast. Also known as crosstrees in older vessels.
• Spring, to - In a wooden vessel, a plank in the hull springs when one of its ends breaks loose, and because of its shape bent to the curve of the hull, springs outwards beyond that curve. Such a plank is said to be sprung.
• Spring a Leak - To develop a hole or break in the hull through which seawater could enter. Term originated from a sprung plank.
• Spring Line - A dock line leading forward or aft, to prevent a vessel from moving ahead or astern. The after bow spring line is attached near the bow and runs aft, where it is attached to the dock. The forward quarter spring line is attached to the quarter of the boat, and runs forward, being attached to the dock near the bow of the boat.
• Spring Tides - The tides found during a New Moon or Full Moon. They run the strongest and are the highest and lowest tides experienced in the tidal cycle.
• Sprit - (1) A spar that extends from the bow of the boat. (2) A spar stretching diagonally across a four-sided fore-and-aft sail to support the peak.
• Spritsail - A four-sided fore-and-aft sail set on a sprit.
• Spume - Froth of sea foam.
• Spunyarn - Small line consisting of several loosely twisted yarns.
• Squall - A sudden and violent gust of wind often accompanied by rain.
• Square - On a square-rigged ship, the yards are square by the braces when they are at right angles to the fore-and-aft lines of the ship.
• Square Rigger - Large ships dating back to the 17th century typically with three masts carrying rectangular sails mounted on horizontal spars called yards. A sailing-ship rig with rectangular sails set approximately at right angles to the keel line from horizontal yards.
• Square Knot - A knot consisting of two overhand knots used to join two lines of similar size.  Also called a reef knot.
• Squawk Box - Ship's intercom system
• Stability - The tendency in a boat to keep an upright position or to return to it when careened over.
• Stabilizers - Wing-like retractable devices extending from the sides of the vessel to dampen down rolling in seas and produce a steadier, smoother, and more comfortable motion.
• Staghorn - A bollard with horizontal arms, forming the shape of a cross, as a means of belaying lines.
• Staith - Elevated structure from which coal and other cargoes can be loaded into a vessel. Name is also given to a landing-place, or loading-place.
• Stall - (1) To stop moving. (2) Usually air travels smoothly along both sides of a sail, but if the sail is not properly trimmed, the air can leave one of the sides of the sail and begin to stall. Stalled sails are not operating efficiently.
• Stalling - The turbulent effect of air on the lee side of a sail when trimmed in too far.
• Stanch - Said of a vessel that is firm, strong, and unlikely to develop leaks.
• Stanchion - A vertical support for guardrails and lifelines.
• Stand-on Vessel - One that has the right-of-way and should maintain her course and speed during a crossing or overtaking situation, unless a collision appears imminent. (Was formerly called "the privileged vessel.")
• Standing Part - That part of a line which is made fast. The main part of a line as distinguished from the bight and the end.
• Standing Rigging - The part of a ship's rigging which is permanently secured and immovable; e.g. stays, shrouds, etc.
• starb'd - Starboard.
• Starboard - The right side of the boat when facing forward.
• Starboard Tack - A sailboat sailing on a tack with the wind coming from starboard and the boom on the port side. If two boats under sail are approaching, the one on port tack must give way to the boat on starboard tack.
• Stargazer - On a square-rigged ship, a small sail set in light weather above the moonraker.
• Stateroom - Cabin; sleeping compartment.
• Station Bill - A list showing the stations of all members of the crew during any maneuver.
• Stave, to - To cause a break in the hull which may sink the vessel; the vessel is then called stove.
• Stave Off - To hold off a boat with a staff, boathook, long spar, etc., to prevent her from coming along too heavily. also known as Fend Off.
• Stay - A line or wire from the mast to the bow or stern of a ship, for support of the mast; rigging used to support the mast from forward or aft.
• Stays - During the operation of tacking, the moment when a sailing vessel is head to the wind and hanging there, with her head not paying off on the opposite tack. Such a vessel is said to be "in stays" or "in irons".
• Staysail or Stays'l - A triangular fore-and-aft sail carried on a stay. A sail that is set on a stay, and not on a yard or a mast. On a cutter this is the sail located between the jib and the main sail
• Steadying Sail - Also stability sail or riding sail. Any small sail set to help the boat maintain its direction without necessarily moving, as when at anchor or in heavy weather.
• Steamer - A steamship. A ship propelled by a steam engine.
• Steaming Light - A white navigation light carried by vessels under way at night to indicate their presence and give an indication of their course.
• Steep Seas - Tall and short waves caused by water current and wave directions being opposite to the direction of the wind.
• Steerage - The after part of a vessel having the poorest accommodations and occupied by the steerage passengers, or those paying the lowest fare.
• Steerageway - Sufficient movement through the water to allow the boat to be controlled and steered by the rudder.
• Stem - The forward edge of the bow. On a wooden boat the stem is a single timber.
• Stem, to - A term indicating that a vessel is holding her own against a contrary current.
• Stemming - Maintaining position over the ground when underway in a river or tidal stream.
• Stempost - The principal vertical timber in a ship's bow.
• Step - A recess into the keel or a framework fixed to the keelson in which the mast is placed
• Step the Mast - Erecting the mast on the boat. The Mast Step is a fitting which supports the bottom end of the mast at the deck or keel.
• Stepped - A mast that is in place is stepped.
• Stern - The back (aftermost) part of a boat.
• Stern Line - A line running from the stern of the boat to a dock or pier when moored.
• Stern Post - (1) A large casting shaped to allow the propeller blades to revolve. The rudder is fitted on the after post. (2) The principal vertical timber in a ship's stern, upon which the rudder is fastened.
• Stern Pulpit or Stern Rail - A sturdy railing or elevated guard rail around the deck at the stern. also known as Pushpit
• Stern Tube - The bearing which supports the propeller shaft where it emerges from the ship.
• Sternway - The backward motion of the ship.
• Stevedore - One who is employed in the working of cargo when a ship is being loaded or unloaded in port.
• Stiff - Said of a boat that resists heeling, or returns quickly to the vertical when rolling in a heavy seaway.
• Stirrups - On a square-rigged ship, the short pieces of line which hang from the yards and support the footropes on which the topmen stand while working aloft on the sails.
• Stock - A crossbeam at the upper part of an anchor.
• Stopper Knot - A knot used to form a knob in the end of a line to prevent the end from running through a block or other narrow space.
• Stops - Small lines used to tie the sails when they are flaked or furled.
• Store(s) - A general term for provisions, materials and supplies used aboard ship for the maintenance of the crew, and for the navigation, propulsion and upkeep of the vessel and its equipment.
• Storm Bound - Confined to an anchorage or haven through being unable to proceed because of stormy weather.
• Storm Trysail - A very strong sail used in stormy weather. It is loose footed, being attached to the mast, but not the boom. This helps prevent boarding waves from damaging the sail or the rigging.
• Stow - To pack or store away; especially, to pack in an orderly, compact, safe manner.
• Stowage - The placing of goods in a ship in such a way as to ensure the safety and stability of the ship not only on a sea or ocean passage but also in between ports when parts of the cargo have been loaded or discharged.
• Stowaway - Illegal passenger who hides himself on board a ship in order to gain free passage or to escape from a country.
• Strainer - Filtering device used to remove the solid debris from the cooling water.
• Strake - On wooden boats, a line of planking running from the bow to the stern along the hull.
• Strand - (1) A number of fibers twisted together ready to be laid up into a rope with other strands. (2) A vessel is stranded when she is driven ashore or onto a shoal by the force of the weather.
• Stretch Off the Land - Old sailing ship term for taking a nap.
• Strike - To lower, as in "Strike the sails", or "Strike the colors".
• Strike Down - On a square-rigged ship, the act of lowering a spar or yard to the deck.
• Stringer - A longitudinal stiffener for the side of a ship, made of angle bar, bulb angle channel or plates, etc. Depending upon their locations, stringers are known as bilge stringers, side stringers, hole stringers, etc.
• Strut - Metal fitting attached to the hull that supports and aligns the aft portion of the propeller shaft.
• Studding Out a Sail - Extending a sail using a whisker pole
• Studdingsail - On square-rigged ships, an additional sail set in good weather outside the square sails when the wind was abaft the beam. Pronounced "Stun-s'l"
• Stuffing Box - A fitting around the propeller shaft to keep the bearing lubricated and to keep water out of the boat.
• Suck the Monkey - Originally, to suck rum from a coconut, the end of the nut resembling a monkey's face. Later, illicitly to suck spirit from a cask, usually through a straw. Also called Bleed the Monkey.
• Sump Pump - Small pump for shower drainage
• Sun Over the Yardarm - Also referred to as "Elevenses."* A traditional maritime saying to indicate that it is time for a morning drink, it was generally assumed that in northern latitudes the sun would show above the foreyard of a ship by 11:00 which was approximately the time in many ships of the forenoon "stand-easy", when many officers would slip below for their first drink of the day.
• Sundowner - A slang name for a bullying officer on a ship.
• Superstructure - Any structure built above the top full deck, such as a deck house, bridge, etc.
• Superstitions - Here are a few old superstitions of seamen: (1) When a ship was launched or about to sail on a long voyage, a libation was offered to the gods of the sea by pouring wine upon the deck so that good fortune would accompany the ship. (2) Flowers carried on board were destined to form a wreath, indicating death. (3) To hear bells at sea is a sign of oncoming death. (4) It is bad luck for a ship to begin a voyage on a Friday. (5) Women on board were considered to be a sign of bad luck (6) Gales and high winds would subside if a naked woman appeared before them (hence many figureheads depicted a woman with a naked breast). (7) In a calm, whistling will bring wind, but whistling while the wind is blowing will bring a gale.
• Surge - Rising and falling of the sea, usually due to wave action.
• Swab - A mop made from rope; to use such a mop.
• Swallow - The space between the two sides of the shell of a block in which the sheave is fitted.
• Swallow the Anchor - To retire from a life at sea and settle ashore.
• Swamp - To fill with water, but not settle to the bottom.
• Sweat, Sweat Up - To haul on a rope, to haul up tight, to hoist the last possible inch or so.
• Swell - Succession of long and unbroken waves that are not due to meteorological conditions in the vicinity. Generally due to wind or storms at a distance from the position.
• Swinging Bridge - A bridge that swings away from the waterway so that boats may pass beside it.
• Swinging Circle, Swinging Room - The distance a boat can move around its anchor. Swinging room is important because if other boats or objects are within a boat's swinging circle they may collide.
• Swinging Ship - The process of checking the accuracy of and adjusting the ship's magnetic compass.
• Swivel - A rotating fitting used to keep a line from tangling.
• Symbols - Marks of identification.

T  [ Tango ] - [meaning]

• Tabernacle - A hinged mast step located on deck. Since it is hinged, the mast may be raised and lowered easily.
• Tabling - Extra fabric sewn around the edges of sails to reinforce the bolt rope sections.
• Tachometer - A gauge that measures engine revolutions per minute.
• Tack - (1) The lower forward corner of a triangular sail (2) The direction that a boat is sailing with respect to the wind. A sailboat cannot sail directly into the wind, and must therefore sail a zig zag course to windward, at about a 45 degree angle to the wind. (3) To change a boat's direction, bringing the bow through the eye of the wind.
• Tacking - To change a boat's direction, bringing the bow through the eye of the wind.
• Tackle - [image] - A purchase where two or more blocks are used to increase mechanical advantage, or the power exerted on a line. (pronounced "taykle").
• Taffrail - The after rail at the stern of a ship. Also called a Pushpit
• Taffrail Log - A propeller drawn through the water that operates a meter on the boat registering the speed and distance sailed
• Tail - The end of a line.
• Take In - To remove a sail.
• Tall Buoy - A float with a flag at the top of a pole. Used to mark a position such as for a mooring, a race or a man overboard.
• Tally Board - Board, bearing instructions, that comes to a wrecked ship with a life-saving rocket line.
• Tally Book - Book in which is kept a reckoning of items of cargo received or discharged from a hatch or vessel.
• Tang - A metal fitting on the mast that the stays attached to the mast; a fitting on the mast for securing rigging.
• Tanker - A tanker is a bulk carrier designed to transport liquid cargo, most often petroleum products.
• Tanks - Are of two kinds: First, those built in permanently and part of the ship's structure, used for the reception of water ballast, fuel, oil, or liquid cargo; second, those constructed specially and removable if necessary. These vary greatly in size and shape and the purpose for which used.
• Tar - (1) Old nickname for a sailor, who would treat his canvas coats and hats with tar as a protection against the weather. (2) The distilled residue of gum extracted from pine trees, used for preserving many things.
• Taut - Stretched tight with no slack.
• Telltales - Ribbon, yarn, or other lightweight material attached to rigging or sails to indicate wind action or direction. Proper use of the telltales can help sailors improve their sail trim.
• Tender - (1) Describing a boat that lacks stability. (2) A small dinghy or launch used to transport crew and equipment from shore to a larger boat (3) One who serves as a precautionary standby, such as a line tender 
• Tenon - The bottom of the mast, with a shape designed to fit into the mast step.
• Territorial Waters - That portion of the sea up to a limited instance which is immediately adjacent to the shores of any country and over which the sovereignty and exclusive jurisdiction of that country extend.
• Tether - A line attached between a safety harness and a secure part of the boat.
• The Hard - Land
• Thimble - A pear-shaped, grooved metal fitting around which an eye splice is made
• Third Assistant Engineer - Maintains lighting fixtures. Repairs malfunctioning accessories in living quarters. Assist other engineers as directed.
• Third Mate - Makes sure emergency survival equipment (lifeboats, life rings, etc.) are in order. Assists other officers as directed.
• Thole, Thole Pin - Metal or wooden peg inserted in gunwale of a boat for an oar to heave against when rowing without crutch or rowlock.
• Three Point Hydroplane - A hydroplane that has two sponsons, one at each side of the hull. The sponsons lift the hull so that, at high speeds, only they and the propeller are in contact with the water, hence three points.
• Three Sheets to the Wind - A phrase with a nautical derivation, meaning a man under the influence of drink or unsteadiness through drink.
• Throat - The forward upper corner of a four-sided sail. Also refers to the jaws of a gaff.
• Thwart - A seat or brace running laterally across the width of a rowing boat.
• Thwartships - Across the width of a boat. Also Athwartships.
• Ticket - A certificate issued as a result of an examination of competency and experience. Some refer to their USCG license as their ticket
• Tidal Atlas - Small charts showing tidal stream directions and rate of flow.
• Tidal Current - The horizontal movement of the water due to tide
• Tidal Range - The difference in depth between high and low tide.
• Tiddley - Term meaning smart or neat.
• Tide - The predictable, periodic regular rising and lowering of water in some areas due to the pull of the sun and the moon. Tidal changes can happen approximately every 6 or 12 hours depending on the region.
• Tide Rip - Short waves or ripples made by a tide as it ebbs or flows over an uneven bottom, or where two currents meet at sea.
• Tide Table - A publication predicting the time and height of high tide and low tide.
• Tiller - A bar or handle for turning a boat's rudder or an outboard motor, thereby steering the boat.
• Tiller Extension - Hinged extension of the tiller which allows the skipper to control the tiller while hiking or sitting forward.
• Timber Hitch - [image] - Method of securing a line around a spar by taking the standing part around the spar, then a half hitch around itself and the end tucked three or four times around its own part.
• Timbers - On wooden vessels, the frames or ribs of a ship, connected to the keel, which give shape and strength to the ship's hull.
• Toe-rail - A small low rail around the deck of a boat. The toe rail may have holes in it to attach lines or blocks and to allow drainage. A larger wall is known as a gunwale.
• Tom Cox's Traverse - Work done by a man who bustles about doing nothing. Usually amplified by adding "running twice round the scuttle butt and once round the longboat".
• Ton - A measure of weight ashore and a measure of capacity on a vessel.
• Tonnage - A measure of a vessel's interior volume; The weight or displacement of a ship.
• Top - on square-rigged ships, a platform at the masthead resting on the trestletrees and crosstrees. In addition to being a work platform, it extended the topmast shrouds to give additional support to the topmast.
• Top Hamper - That portion of a vessel above the main deck.*
• Topgallant - (1) The mast section next above the topmast and and below the royal mast. (2) The yard supported by that mast. (3) The third lowest square sail. It is stretched between the topgallant yard and the top yard.
• Topmast - A second mast carried at the top of the fore or main mast, used to fly more sail.
• Topmen - Seamen who worked on the masts and yards of square-rigged ships.
• Topping Lift - (1) A line by which the end of a spar is hoisted or lowered. (2) A line that holds up the boom when it is not being used. (3) A line from the upper mast which controls the height of the spinnaker pole.
• Topsail - The sail above the lowermost sail on a square-rigged ship; also, the sail set above and sometimes on the gaff on a gaff rigged boat.
• Topsail Schooner - A schooner with a square rigged sail on the forward mast.
• Topside - Above the main deck.
• Topsides - (1) The sides of a vessel between the waterline and the deck. (2) Referring to on or above the deck; "I'm going topsides".
• Touch and Go - To touch the ground, with the keel, for a minute or so and then proceed again.
• Tow - To pull a boat with another boat, such as a tugboat towing a barge. When used as a noun, it refers to the vessel being towed.
• Track - (1) Prospective course over the ground for boat to follow. (2) A strip of metal attached to a mast to take the slides affixed to the luff of a sail.
• Trade Winds - Steady regular winds in a belt approximately 30° North and 30° South of the equator.
• Traffic Separation Zone - The area between opposing shipping lanes, restricted to most navigation except for crossing with caution
• Trailing Edge - The aft edge of a sail, more commonly called the leech.
• Tramp Service - Vessels operating without a fixed itinerary or schedule or charter contract.
• Transit - Two navigational aids separated in distance so that they can be aligned to determine that a boat lies on a certain line. Transits can be used to determine a boat's position or guide it through a channel. Also called a range.
• Transom - The athwartship portion of a hull at the stern. The flat, vertical aft end of a ship.
• Transverse - Placed at right angles to the keel, such as a transverse frame, transverse bulkhead, etc.
• Transverse Bulkhead - A bulkhead placed athwartships.
• Trapeze - A belt and line or wire used to help a crew hike out beyond the edge of a boat to counteract the boat's heel. Usually used on small vessels for racing.
• Traveler - A slide which travels on a track to which the mainsheet may be attached. The sail shape can be subtly altered by changing the mainsheet position on the traveler.
• Trawl - A large net with its mouth held open, towed by a trawler along the bottom to catch bottom fish.
• Trawler - A fishing vessel designed to tow a trawl for catching bottom fish.
• Trawlwire - Heavy-duty wire used to lower heavy instruments overboard from the trawl winch.
• Treenails - In wooden ship construction, these were cylindrical pins of oak which were used to secure the planks to her timbers. Pronounced "trennels".
• Trestle Trees - Two short pieces of timber fixed horizontally fore and aft on each side of the lower masthead of a square rigged vessel and used to support the topmast, the lower crosstrees, and the top.
• Triatic Stay - A stay leading from one mast, such as the main mast to another, such as the mizzen mast.
• Trice - To haul up by pulling downwards on a rope that is led through a block or sheave.
• Trice Up - The order or action of tying up hammocks in the morning, thus generally applied to putting one's berth and area into order for the day.*
• Trick - A spell of duty connected with the navigation of a vessel; more particularly, at the wheel or look-out.
• Tricolor Light - A running light allowed on some sailboats instead of the normal bow and stern lights. The tricolor light contains the red and green side lights and the white stern light in a single fitting that is attached to the top of the mast.
• Trim - (1) To adjust the sails for best advantage. (2) Fore and aft balance of a boat. If either the bow or stern is depressed, the vessel is said to be down by the bow or down by the stern. (3) To trim is to adjust. It does not just apply to sheets. You can trim the boat or ship (i.e. improve it’s balance)
• Trim Tab - An adjustable section of the rudder that allows the rudder to be corrected for lee helm or weather helm.
• Trimaran - A multihulled boat with three hulls.
• Trip an Anchor - The act of breaking out the flukes of an anchor if they are caught on some obstruction, preventing it from being normally weighed.
• Tripline - A line attached to the crown of an anchor and used to help free it in the event it becomes fouled.
• Trolling -  To fish by trailing a baited line from behind a slowly moving boat.
• Tropics - The region around the equator between the Tropic of Cancer and the Tropic of Capricorn. The tropics are known for their warm weather.
• Trough - The bottom of a wave, the valley between the crests.
• Truck - A cap for the top of the mast.
• True Course - A course steered by the compass that has been corrected for variation and deviation
• True North Pole - The north end of the earth's axis and also called North Geographic Pole. The direction indicated by 000° (or 360°) on the true compass rose, it is the direction of the North Pole from any place on the earth's surface.
• True Wind - The speed and direction of the wind felt or measured when stationary. The motion of a boat will cause the wind to appear to be coming at a different direction and speed, which is known as apparent wind
• Trunk - The tall, narrow, waterproof box that houses a vessel's centerboard and allows it to be retracted into the ship's hull.
• Trysail - A small, heavy triangular loose-footed sail fitted aft of the mast and used primarily in very strong winds.
• Tug, Tugboat - A powerful, strongly built boat designed to tow or push other vessels, and to assist in maneuvering a ship in a confined area.
• Tumble Home - The distance the ship's side falls in towards the center line above the load water line. Opposite of flare.
• Tuning - The adjustment of the standing rigging, the sails and the hull to balance the boat for optimum performance.
• Turk's Head - [image] - An ornamental knot to provide a stopper on the end of a line.
• Turn - Complete encirclement of a cleat, bollard, pin or winch by a line. 
• Turn of the Bilge - The point where the bottom and the sides of a ship join.
• Turn Up - To fasten a rope securely by taking turns around a cleat or bollard.
• Turn To - Get to work.*
• Turnbuckle - A threaded, adjustable fitting, used for stays, lifelines and sometimes other rigging. It is used to to maintain correct tension on standing rigging. Can also be used to pull objects together.
• Turning Block - Horizontally mounted block used to re-direct a line on deck.
• Turning Mark - A buoy on the race course around which boats must turn.
• Turtle - (1) To tip the boat over so that the boat is upside down with the mast pointing down to the sea bottom. (2) A bag in which a spinnaker or other large sail can be stowed with the lines attached so that it can be rapidly raised.
• Turtle Back - The top of a wheelhouse, forecastle, etc., having the form of a turtle's back.
• 'tween Decks - The space between any decks.
• Twine - Small line used for whipping other light duties.
• Twing - Similar to a Barber hauler, a twing adjusts the angle of sheeting.
• Two Half Hitches - A knot with two half hitches loops - on the standing part of the line.
• Two-block - To reach the end; to bring one object hard up against another, as when two blocks in a block and tackle arrangement are brought together.
• Typhoon - A strong tropical counterclockwise revolving storm the southern hemisphere. In the northern hemisphere these storms revolve clockwise and are known as hurricanes.

U  [ Uniform ] - [meaning]

• Ullage - (1) An old term to denote a lazy sailor who is of little use on the ship. (2) Damaged goods, especially provisions.
• Unbend - To cast adrift
• Under Bare Poles - Having no sails up. In heavy weather the windage of the mast and other spars can still be enough to move the boat.
• Under the Lee - On the lee side of an object, protected from the wind.
• Under Foot - Said of anchor when it is under ship's forefoot, and cable is nearly up and down.
• Undertow - Strong offshore current extending to the shore.
• Underway - Not attached to the shore or the ground in any manner. Usually, but not necessarily, moving through or making way through the water.
• Unfurl - To unfold or unroll a sail. The opposite of furl.
• Unmoor - To cast off hawsers by which a vessel is attached to a buoy or wharf.
• Unreeve - To run a line completely through and out of a block, fairlead, etc.
• Unrig - To remove or disassemble gear after it is used.
• Unseaworthiness - The state or condition of a vessel when it is not in a proper state of maintenance, or if the loading equipment or crew, or in any other respect is not ready to encounter the ordinary perils of sea.
• Unship - To remove from a ship. To remove an item from its place.
• Up and Down - Said of cable when it extends vertically and taut from anchor to hawsepipe.
• Upper Deck - The highest continuous deck which runs the full length of the ship without a fall or interruption.
• Upwind - To windward, in the direction of the eye of the wind; toward the wind; in the direction from which the wind is coming

V  [ Victor ] - [meaning]

• V-Berth - Usually the forward berth of the boat, located in the bow
• V-Bottom - A hull with the bottom section in the shape of a "V."
• Van - The leading ship, or ships, in a fleet or squadron.
• Vane - A small flag placed at the mast head to show wind direction.
• Vang - A control line, usually a multi-purchase tackle, secured to the boom to prevent it from lifting. Can also apply to other spars, such as gaffs.
• Variation - Magnetic variation. The difference, east or west, between magnetic north and true north, measured as an angle. Magnetic variation varies in different geographic locations.
• Vector - A line drawn to indicate both the direction and magnitude of a force, such as leeway or a current.
• Veer - A shifting of the wind direction, opposite of backing. Clockwise in the northern hemisphere, counter-clockwise in the southern hemisphere.
• Velocity Made Good - Also VMG. Actual boat speed after adjusting for such factors as current and leeway.
• Ventilator - A device for furnishing fresh air to compartments below deck or exhausting foul air. Construction designed to lead air below decks. May have a cowl, which can be angled into or away from the wind; and may be constructed with baffles, so that water is not allowed below, as in a Dorade ventilator.
• Venture - An enterprise in which there is a risk of loss.
• Vertical Clearance - The distance between the water level at chart datum and an overhead obstacle such as a bridge or power line.
• Vessel - A general term for a floating craft that carries passengers, cargo or both
• VHF Radio - An electronic communications or direction finding system which uses Very High Frequency radio waves. VHF radios are the most common communications radio carried on boats, but their range is usually limited to line of sight between the transmitting and receiving stations.
• Vice Admiral - A naval rank next below that of admiral.
• Vigia - Uncharted navigational danger that has been reported but has not been verified by survey.
• Visual Fix - A fix taken by visually observing the location of known landmarks.
• Voyage - A journey made at sea by a vessel, usually including both the outbound and homebound passages.

W  [ Whiskey ] - [meaning]

• Waist - That part of the upper deck of a ship between the forecastle and the quarterdeck, or on sailing ships, between the fore and main masts.
• Waister - An old term to describe an untrained or incompetent seaman, or one who was worn out after many years of work.
• Wake - Moving waves, track or path that a boat leaves behind it, when moving through the water; the track of disturbed water a boat leaves as it moves.
• Wall Knot - A stopper not in the end of a line.
• Wardrobe - All the various sails carried on board a yacht.
• Wardroom - Officer's recreation area.
• Warming the Bell - Striking "bells" a little before the proper time at the end of a watch. More generally, doing something unjustifiably or unnecessarily early.
• Warp - (1) To warp is to move a vessel by lines - move a boat by hauling on lines attached to docks or anchors. (2) The longitudinal threads in canvas and other textiles. (3) Hawser used when warping. (4) The line by which a boat rides to a sea anchor. (5) Mooring ropes.
• Warrant Officer - A range of ranks above enlisted men and below commissioned officers, usually having specialized knowledge and skills.*
• Wash - (1) Broken water at bow of a vessel making way. (2) Disturbed water made by a propeller or paddle wheel. (3) The rush or sweeping of waves on a bank, shore, or vessel.
• Washboards - Boards used to close the companionway.
• Washing Down - Said of a vessel when she is shipping water on deck and it is running off through scuppers and freeing ports.
• Watch - The day at sea is divided into six four hour periods. Three groups of watchstanders are on duty for four hours and then off for eight, then back to duty; also refers to those standing watch as an individual, pair, or group. In order to prevent the same men from keeping the same watch each day, the watch between 1600 and 2000 is divided into two half watches, known as the first and last dog watches, in order to produce an odd number of watches each day.
• Watch Bell - Bell used for striking the half hours of each watch.
• Watch Buoy - A buoy moored near a Lightship from which she can check her position to make sure that she has not moved by dragging.
• Water Ballast - Sea water used for ballast, let into the double bottom, or into a water-ballast tank, or trimming tanks.
• Water Breaker - Small cask used for carrying drinking water in a boat.
• Water Stop - A dowel driven through a hole that is drilled across a seam, to prevent leakage, usually in structural members. ¹
• Waterline - The line where the water comes to on the hull of a boat. Design waterline is where the waterline was designed to be, load waterline is the waterline when the boat is loaded, and the painted waterline is where the waterline was painted. Actual waterline is where the waterline really is at any given time.
• Waterline Length - The length of the boat at the waterline.
• Waterlogged - Completely filled with water.
• Watertight Bulkhead - A bulkhead that will not let water pass from one side of it to the other.
• Watertight Compartment - A compartment having a watertight bulkhead at each end.
• Waterway - A river, canal or other body of water that boats can travel on.
• Wave - Oscillations of the sea caused by wind blowing along the surface and moving in the direction from which the wind blows.
• Waveson - Goods floating on surface of sea after a wreck.
• Way - A vessel's movement through the water; such as headway, sternway, or leeway.
• Way Enough - Order given to a boat's crew when going alongside under oars. Denotes that boat has sufficient way, and that oars are to be placed inside the boat.
• Waypoint - A charted feature or chosen position on a chart
• Ways - The framework of timber, etc., on which a vessel is built, from which she is launched into the water.
• Wear - 1) To wear a boat is the operation of bringing a sailing vessel onto the other tack by bringing the wind around the stern, as opposed to tacking, where the wind is brought around the bow. 2) In respect to the flying of flags, a ship flies her national flag or ensign, but wears a personal flag.
• Weather - In the direction from which the wind blows, as in weather side of the ship, the side from which the wind is blowing; to windward.
• Weather Board - Windward side of a vessel.
• Weather Deck - A deck exposed to the wind and sea.
• Weather Helm - The natural tendency of a sailboat to come up into the wind. The helm must be held over to keep the boat from coming up
• Weather Proverbs - The ability of a seaman to foretell weather by the appearance of the sky, change of wind direction, etc. was handed down in the form of proverbs. Some well known are:

X  [ X-ray ] - [meaning]

Y  [ Yankee ] - [meaning]

• Y Valve - Liquid flows through into the valve and flows out through one of two tubes which is selected by changing the angle of a lever.
• Yacht - A sailboat or powerboat used for pleasure, not a working boat.
• Yankee - (1) A fore-sail flying above and forward of the jib, usually seen on bowsprit vessels. (2) A foresail used on yachts similar to a genoa, but cut narrower, with its leech not overlapping the mainsail, and a higher clew.
• Yar - Fit and beautiful (describing a boat)
• Yard - A spar from which a square sail is hung. A long spar, tapered at the ends, attached at its middle to a mast and running athwartships at right angles to the mast; used to support the top of a square sail. The yard can pivot (be braced) around the mast. At rest (braced square) the yard runs athwartships. Each yard takes its name from the section of mast that supports it, and the sails take their names from the yards.
• Yardarm - That part of yard that lies between the lift and the outboard end of the yard.
• Yarn - A tall tale sea story
• Yaw - Swinging off course, usually in heavy seas. The bow moves toward one side or the other of the intended course.
• Yawl - A two masted sailboat with the shorter mizzen mast placed aft of the rudder post. A ketch is similar, but the mizzen mast is forward of the rudder post.
• Yawl Boat - Smaller powered boat used to provide steerage-way when not under sail.
• Yellow Jack - Slang name for the Q Flag. Also an old term for yellow fever.

Z  [ Zulu ] - [meaning]

• Zebra Mussel - A small freshwater mollusk that was accidentally introduced to North American waters via ballast water from a transoceanic vessel. The zebra mussel has had significant negative economic and ecological effects: It clogs water intake pipes and attaches to and fouls boat hulls, dock pilings and other objects.
• Zenith - The point of the celestial sphere which is directly overhead.
• Zenith Angle - The angle between the zenith and a heavenly body.
• Zephyr - A gentle breeze; the slightest movement of air.
• Zincs - Sacrificial anodes placed on a vessel to prevent electrolysis of vital metal parts.
• Zulu - Used to indicated times measured in Coordinated Universal Time, a successor to Greenwich Mean Time. A time standard that is not affected by time zones or seasons.