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ADMIRALTY LAW: Body of law that deals with maritime cases.


AID TO NAVIGATION: Any device external to a vessel specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation, common examples are lighthouses, buoys and channel markers.


ALLISION: Vessel impacting a stationary object, such as a bridge abutment, pier or wharf, or another vessel made fast to a pier or wharf. Rather than "collide," The vessel "allides" with the fixed object.  Most commonly, but not always, an allision is the fault of the moving vessel, as opposed to the stationary object, but there are exceptions, such as when a bridge is supposed to raise to a certain height, but fails to do so causing the allision.


ALONGSIDE: By the side of a ship or pier


AMIDSHIPS: The middle section of a vessel, as distinguished from port (left) or starboard (right).


ANCHORAGE: Area of a port or harbor suitable for vessels to lay at anchor.


ARC OF VISIBILITY: The section of the horizon over which a lighted aid to navigation is visible from seaward.


ASTERN: Toward the back of a vessel or behind a vessel.


BALLAST: Heavy material or sometimes water that is placed in the hold of a vessel to provide stability.


BAREBOAT CHARTER: An arrangement for the lease of a vessel, whereby the vessel's owner provides no crew or provisions as part of the agreement; instead, the people who rent the vessel are responsible for crewing and provisioning her.


BEAUFORT SCALE: The scale describing wind force.


BERTH: A location in a port or harbor used for mooring vessels while not at sea


BOLLARD: A vertical pillar on the quay to which lines to a ship may be made fast.


BOSUN (aka BOATSWAIN): A non-commissioned officer responsible for the sails, ropes, rigging and boats on a ship.


BOW: The front of a vessel, most often the pointy end, also called the prow.  There are many variations of a bow, including but certainly not limited to bulbous (A protruding rounded structure at the front of a ship just below the waterline which modifies the way water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability) and raked, which is a slanted bow designed to reduce resistance as the vessel moves forward through the water.

BRIDGE (as part of a vessel): A structure above the weather deck on a vessel, which houses a command center.


BROADSIDE: The simultaneous firing of all the guns on one side of a warship.


BULK CARRIER: A merchant ship designed to transport unpackaged bulk cargo in its holds


BULKHEAD: An upright wall within the hull of a ship, often watertight.


BULWARK: The extension of the ship's side above the level of the weather deck.


BUNKERS: fuel oil for a ship (not to be confused with a school of oily bait fish).


BUOY: A floating object varying in shape and color depending on its purpose, including Can (A type of navigational buoy often a vertical drum, square in silhouette, in channel marking its use is opposite that of a “nun buoy” which is always triangular in silhouette) Anchor buoy (A small buoy secured by a light line to an anchor to indicate position of anchor on bottom) Bell (A type of buoy with a large bell that rings by wave action).

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CABOTAGE: The transport of goods or passengers between two points in the same country, alongside coastal waters, by a vessel.  In the United States, it has particular importance in The Jones Act.


CAPSIZE: When a ship or boat lists too far and rolls over, exposing the keel.


CAPSTAN: A large winch with a vertical axis, used to wind in anchors or other heavy objects.


CAPTAIN OF THE PORT: In the United States, a US Coast Guard officer, responsible for enforcement of safety, security, and marine environmental protection regulations in a commercial port.


CENTERLINE: An imaginary line down the center of a vessel lengthwise.


CHAFING: Wear on a rope caused by constant rubbing against another surface.


CHAFING GEAR: Material applied to a rope to prevent or reduce chafing.


CHARTER PARTY: the written contract for the lease of a vessel.


CHOCK: An opening in a ships bulwark normally oval in shape designed to allow mooring lines to be fastened to cleats or bits mounted to the ship's deck.


CLEAT: A stationary device used to secure a rope aboard a vessel.


COAMING: The raised edge of a hatch, cockpit or skylight to help keep out water.

Cruise ship: A passenger ship used for pleasure voyages, as opposed to transportation, where enjoyment of the voyage itself is the purpose of the trip.


DECK HAND: A person whose job involves (un)mooring, anchoring, maintenance, and general work on a vessel. The lowest ranking commercial seaman.


DERRICK: A lifting device composed of one pole and a boom which is hinged freely at the bottom.


DISPLACEMENT: The weight of water displaced by the immersed volume of a ship's hull, equivalent to the weight of the whole ship.


DOLPHIN: A structure consisting of a number of piles driven into the seabed or riverbed as a marker, as opposed to either the fish or mammal of the same name.


DUNNAGE: Packing material used to protect a ship's cargo from damage during transport.



EXTREMIS: (also known as "in extremis") the point under International Rules of the Road (Navigation Rules) at which the privileged (or stand-on) vessel on collision course with a burdened (or give-way) vessel determines it must maneuver to avoid a collision. Prior to extremis, the privileged vessel must maintain course and speed and the burdened vessel must maneuver to avoid collision.


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FANTAIL: Back end of the ship, also known as the Poop deck.


FATHOM: A unit of length equal to 6 feet (1.8 m), roughly measured as the distance between a man's outstretched hands. Particularly used to measure depth.


FATHOMETER: A depth finder to determine the depth of water.


FENDER: On a vessel, a flexible bumper used to keep boats from banging into docks or each other, often seen as old tires hanging from the side of a tugboat.


FIRST MATE or CHIEF MATE: The second-in-command of a commercial ship.


FLAG OF CONVENIENCE: The business practice of registering a merchant ship in a country different from that of the ship's owners, and flying that state's civil flag on the ship. The practice allows the ship's owner to reduce operating costs or avoid the regulations of the owner's country.  A common example is where a vessel with no other connection to the country, fly the Liberian flag.


FLANK: The maximum speed of a ship. Even faster than "full speed ahead."


FLOTSAM: Debris or cargo that remains afloat after a shipwreck, to be distinguished from "jetsam" which is cargo thrown intentionally overboard to lighten a vessel in jeopardy of foundering.


FOLLOWING SEA: Wave or tidal movement going in the same direction as a ship.

Fore: Forward or towards the bow


FORECASTLE: Pronounced Focsle; a partial deck, above the upper deck and at the head of the vessel; traditionally the sailors' living quarters.


FOREPEAK: The part of the hold of a ship within the angle of the bow.


FOUNDER: To fill with water and sink


FREEBOARD: The height of a ship's hull above the waterline. The vertical distance from the current waterline to the lowest point on the highest continuous watertight deck.


FREIGHT: The amount of money a ship earns for carrying cargo or passengers. Often confused with cargo.


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GANGPLANK: A movable bridge used in boarding or leaving a ship at a pier; also known as a "brow" or "gangway."


GIVE-WAY (vessel): Where two vessels are approaching one another so as to involve a risk of collision, this is the vessel which is directed to keep out of the way of the other.


GUNWALE or GUNNEL: The upper edge of the hull. The top of the rail round the outer edge of the deck.



HATCHWAY, HATCH: A covered opening in a ship's deck through which cargo can be loaded or access made to a lower deck; the cover to the opening is called a hatch or hatch cover.


HEAVE: A vessel's vertical, up-and-down motion.


HEEL: The lean of a vessel caused by wind, wave or maneuvering


HOME PORT: The port at which a vessel is actually based, which may not necessarily be its port of registry, which is the port listed in the vessel's registration documents and lettered on written on her stern.


HULL: The shell and framework of the basic flotation part of a ship.


ICING: A hazard where cold temperatures combined with high wind speed result in spray blown off the sea freezing on contact with the ship.


INBOARD: Situated within a vessel.



KEEL: The central structural basis of the hull.


KEELHAULING: A torturous death sentence carried out by dragging the sentenced sailor under the keel of a ship.


KNOT: A unit of speed: 1 nautical mile equal to (1.1508 miles) per hour.



LAZARET: A small stowage locker at the aft end of a boat


LEAGUE: A unit of length equal to three nautical miles.


LEEWARD: In the direction that the wind is blowing towards.


LEEWAY: The amount that a ship is blown leeward by the wind. Also the amount of open free space available to leeward before encountering hazards.


LEG: In navigation, a segment of a voyage between two waypoints.


LIGHTER: A small boat used to transfer goods and passengers to and from ships. 


LIST: A vessel's angle of lean or tilt to one side; a lean caused by flooding or shifted cargo.


LOG or LOGBOOK: a record of important events in the management, operation, and navigation of a ship. It is essential to traditional navigation, and must be filled in at least daily.   Various logs include the rough log, the smooth log, the deck log, the engineering log, the radio log, etc.


LOLLING: An uncontrollable list caused by inadequate transverse stability.


LOOKOUT: A member of the crew specifically assigned to watch surrounding waters for other vessels, land, objects in the water, hazards, threats, etc. In the days of sailing vessels, the lookout was normally stationed in the crow's nest for a better vantage point.


LOWER DECK: The deck of a ship immediately above the hold.

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MAGNETIC BEARING: An absolute bearing using magnetic north.


MAGNETIC NORTH: The direction towards the North Magnetic Pole.


MAIN DECK: The uppermost continuous deck extending from bow to stern;  often the weather deck.


MAKING WAY: When a vessel is moving under its own power.


MANIFEST: A document listing the cargo, passengers, and crew of a ship for the use of customs and other officials.


MASTER: the captain of the vessel.


METACENTER: The midway point between a vessel's center of buoyancy when upright and her center of buoyancy when tilted.


METACENTRIC HEIGHT: A measurement of the initial static stability of a vessel afloat, calculated as the distance between her centre of gravity and her metacenter. A vessel with a large metacentric height rolls more quickly; a vessel with a small metacentric height will roll more slowly.


MIDSHIPS: The middle section of a vessel with reference to the longitudinal plane, as distinguished from fore or aft.



NARROWS: A narrow part of a navigable waterway.


NAUTICAL MILE: A unit of length longer than a land-based mile, corresponding to one minute of arc of latitude along any meridian arc. 1 mile on land is rounded to 0.86 nautical miles.  One nautical mile is 1.1508 land miles.


NAVIGATION RULES: Rules of the road that provide guidance on how to avoid collision and also used to assign blame when a collision does occur.



PARLEY: A discussion or conference, especially between enemies, over terms of a truce or other matters.


PASSAGEWAY: Hallway of a ship.


PIER: A raised structure, supported by piles or pillars, used for loading and unloading ships.


PILOT: A navigator with special knowledge of local waters, normally brought on board a vessel to navigate same through a particularly treacherous passage.


PIRACY: An act of robbery or criminal violence at sea by the occupants of one vessel against the occupants of another vessel.


PITCH: A vessel's motion, rotating about the beam/transverse axis, causing the fore and aft ends to rise and fall repetitively.


PITCHPOLE: To capsize a boat stern over bow, rather than by rolling over.


PLANE: To skim over the water at high speed rather than push through it; a vessel on plane can move much more economically as it displaces much less water via its forward movement


PLIMSOLL MARK: A special marking, that looks to the untrained eye like a Chinese character, positioned amidships on the outboard whole of the vessel, that indicates the draft of the vessel and the legal limit to which the vessel may be loaded for specific water types and temperatures.


POOP DECK: A high deck on the aft superstructure of a ship.


PORT: The left side of the boat. Towards the left-hand side of the ship facing forward (formerly Larboard). Denoted with a red light.

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QUAY: A stone or concrete structure used for loading and unloading vessels, generally synonymous with a wharf.


REEFER: A shipboard refrigerator.


RELATIVE BEARING: A bearing relative to the direction of the ship: the clockwise angle between the ship's direction and an object. Compared to absolute bearing, which is the bearing of an object in relation to either magnetic or true North.


RIP RAP: A man-made pile of rocks and rubble often surrounding an off-shore lighthouse or as a base for an aid to navigation which asked to prevent the waves and the tides from deteriorating the land or structure it serves to protect.


ROGUE WAVE: An unexpected or uncharacteristically large wave for a given sea state.


ROLL: A vessel's motion rotating from side to side, about the fore-aft/longitudinal axis.



SCUPPERS: A series of pipes or through fittings to drain water from the weather deck overboard.


SCUTTLE OR SCUTTLING: To sink a vessel deliberately.


SEA STATE: The general condition of the free surface on a large body of water with respect to wind waves and swell at a certain location and moment.


SEAMAN: A sailor.


SEAWORTHY: A vessel or appurtenance of a vessel fit for its intended purpose on the sea.


SECOND MATE: Third in command; a watchkeeping officer, customarily the ship's navigator.


SHEER: The upward curve of a vessel's longitudinal lines as viewed from the side


SHEET: A rope.


SHIP'S COMPLEMENT: The number of persons in a ship's crew, including officers.


SHOAL: Shallow water, often exposed to the surface at low tide, that is a hazard to navigation.


SKEG: A projection from the keel in front of the rudder to protect the rudder from damage.


STAND-ON (vessel): A vessel directed to keep her course and speed where two vessels are approaching one another so as to involve a risk of collision; also known as the privileged vessel.


STARBOARD: the right side of the vessel, characterized with a green light.


STEERAGEWAY: The minimum speed at which a vessel will be able to maneuver while under power.


STERN: The rear part of a ship


STOVE, STAVE or STOVE IN: To smash inward, to force a hole or break in.


SUPERSTRUCTURE: The parts of the ship or a boat that project above her main deck.


SWAY: A vessel's lateral motion from side to side.

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TENDER:  A vessel used to provide transportation services for people and supplies to and from shore for a larger vessel.


THREE SHEETS TO THE WIND: A sailor in a state of intoxication.


TONNAGE: Various measures of the size or cargo carrying capacity of a ship, including:

Deadweight tonnage, the total weight of a vessel, mostly without payload.

Displacement tonnage, the total weight of a vessel.

Lightship or lightweight tonnage, the weight of a ship without any fuel, cargo, supplies, water, or passengers, on board.


TRAMP TRADE: Shipping trade in which the vessels involved do not have a fixed schedule or itinerary or published ports of call. A vessel involved in such trade is referred to as a Tramp.


TRANSOM: The aft "wall" of the stern; often the part to which an outboard unit or the drive portion of a sterndrive is attached.  The back or flat end of a vessel as opposed to the bow or pointy end.


TRUE BEARING: An absolute bearing using true north.


TWEENDECK: A deck on a general cargo ship located between the main deck (or weather deck) and the hold space.




UNDER WAY or UNDERWAY: A vessel that is moving under control.



WAKE: Wave like turbulence behind a vessel created by its forward movement; in current nomenclature often used synonymously with wash.


WAY: Controlled speed, progress, or momentum, of a vessel; the point at which there is sufficient water flow past a vessel's rudder for it to be able to steer the vessel.

Weather deck: The deck that is exposed to the weather; usually either the main deck.


WEIGH ANCHOR: To raise an anchor from sea usually to prepare for departure.


WHARF: A structure on the shore of a harbor or on the bank of a river where ships may dock to load and unload cargo or passengers.


WHEELHOUSE: Location on a ship where the wheel is located; also called pilothouse or bridge.


WIDE BERTH: To leave room between two ships moored (berthed) to allow space for maneuver.


WINCH: A small hand operated horizontal geared drum, used to assist in the handling of cable or rope.


WINDAGE: Wind resistance of the boat.


WINDWARD: In the direction that the wind is coming from.



YARDARM: The very end of the horizontal spar from which a square sail is suspended.


YAW: A vessel's rotational motion about the vertical axis, causing the fore and aft ends to swing from side to side repetitively.

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