Marine and Naval Architecture terms have special meaning. Persons studying ship construction, working on board ship, or dockyard will find these pages useful.

	AFT	Back of the vessel.
	AFTER PERPENDICULARS	A vertical line at the intersection of the summer load line and the after side of the rudder post or sternpost, or the centerline of the rudder stock if there is no rudder post or sternpost
	AMIDSHIPS	The middle portion of a ship
	APPENDAGES	Structures extending beyond the main hull. They include items like shafting, rudder, bossing, struts and bilge keels.
	ASTERN	A backward movement of a vessel
	ATHWARTSHIP	Across the ship, at right angles to the fore-and-aft centerline
	BALLAST	Any liquid or solid weight placed in a ship to change the trim, increase the draft, or to regulate the stability
	BALLAST TANK	Tanks at the bottom or sides of a ship which are filled with seawater for ballasting purpose.
	BARGE	Flat-bottomed boat for carrying cargo or bunker oil, usually pulled by tugs.
	BARGE CARRIERS	Ships designed to carry barges. (See LASH and SEABEE)
	BASELINE	A fore-and-aft reference line at the upper surface of the flat plate keel at the centerline for flush shell plated vessels. Vertical dimensions are measured from a horizontal plane through the baseline, often called the molded baseline.
	BEAM	The width of a ship. Also called breadth.
	BEAM, CANT	Beams supporting the deck plating in the overhanging portion of the stern.
	BEAM, DECK	An athwartship horizontal structural member supporting a flat or deck
	BEAM, MOLDED	The maximum breadth of a hull measured between the inboard surfaces of the side shell plating of flush-plated ships
	BILGE	A recess area fitted at the curved section between the bottom and the side into which water drains from holds or other spaces.
	BILGE BRACKET	A vertical transverse flat plate welded to the tank top or margin plate and to the frame in the area of the bilge.
	BILGE KEEL	A long longitudinal fin fitted on the curved of a ship at the turn of the bilge to reduce rolling
	BILGE STRAKE	Shell plates at the bilge area
	BITTER END	The inboard end of a ship's anchor chain that is secured in the chain locker
	BLOCK COEFFICIENT	The ratio of the underwater volume of a ship to the volume of a rectangular block with the same effective lengths, draft and beam
	BODY PLAN	A drawing showing the forms of the various cross sections, the curvature of the deck lines at the side, and the projections, as straight lines of the waterlines, the buttock lines, transverse elevations and the diagonal lines
	BOW THRUSTERS	A propeller at the bow of the ship, used during maneuvering to provide transverse thrust
	BREADTH	See Beam
	BREAKBULK VESSEL	A general, multipurpose, cargo ship that carriers cargoes of nonuniform sizes
	BREAKWATER	Plates fitted on a forward weather deck to form a V-shaped shield against water that is shipped over the bow
	BREASTHOOK	A triangular plate bracket joining port and starboard side stringers at the stem.
	BRIDGE, FLYING	The platform forming the top of the pilot house
	BRIDGE, HOUSE	An erection fitted on the upper or superstructure deck of a ship. The officers' quarters, lounge are usually located in the bridge house
	BRIDGE, NAVIGATING	The command post of a ship.
	BROKEN STORAGE	The spaces between and around cargo packages, including dunnage, and spaces not usable because of structural interference.
	BROW	A small inclined ramp to allow passage of trucks over a hatch coaming or bulkhead door sills etc
	BUCKLER	A portable cover secured over the deck opening of the hawsepipes and the chain pipes to restrict the flow of water through the openings
	BUILDING BASIN	A structure in which one or more ships may be built and floated by flooding the basin.
	BULK CARGO	Cargo such as oil, coal, ore, woodchips, etc. not shipped in bags or containers
	BULK CARRIER	Ship designed to carry cargo such as grain, woodchips, ore, coal, etc. in bulk
	BULKHEAD	Vertical partition walls which separates the interior of a ship into compartments or rooms
	BULKHEAD DECK	The uppermost deck to which the transverse watertight bulkheads are carried
	BULKHEAD, AFTERPEAK	First main transverse bulkhead forward of the sternpost
	BULKHEAD, COLLISION OR FOREPEAK	The foremost main transverse watertight bulkhead designed to keep water out of the forward hold in case of bow collision damage.
	BULKHEAD, SCREEN	Light nonwatertight transverse bulkhead fitted in some Great Lakes ore carriers
	BULWARK	Fore-and-aft vertical plating immediately above the upper edge of the sheer strake
	BUNK	A built-in bed
	BUNKERS	Fuel consumed by the engines of a ship
	BUTT	The end joint between two plates or other members which meet end to end
	BUTT STRAP	A strap that overlaps the butt between two plates, serving as a connecting strength strap between the butted ends of the plating
	CALK OR CAULK	To fill seams in a wood deck with oakum or hammer the adjoining edges of metal together to stop leaks.
	CAMBER	The rise of a deck, athwartship
	CAMEL	A padded fender to keep a vessel away from a pier or quay to prevent damage to the hull or pier
	CANT FRAME	A frame connected at the upper end to the cant beams (See beams, cant.)
	CAPACITY PLAN	A plan outlining the spaces available for fuel, cargo, ballast, fresh water, etc, with guides on weight and volume for spaces at various drafts and displacements
	CAPSTAN	A stump with a vertical axis used for handling mooring and other lines
	CARGO BATTENS	Strips of wood fitted inside the frames to keep cargo away from hull steelwork. Also called sparring
	CARGO PORT	Opening in a ship's side for loading and unloading cargo.
	CARGO SHIFTING	Movements or changing positions of cargo from one place to another which can easily endanger the seaworthiness of the ship
	CATAMARAN	A double hulled vessel
	CATHODIC PROTECTION	Protection of a ship's hull against corrosion by the use of impressed electric current or by sacrificial anodes
	CATWALK	A raised walkway running fore and aft from the midship
	CEILING, HOLD AND TANKTOP	A covering usually of wood, placed over the tank top for its protection
	CEILING, JOINER WORK	The overhead finished surface in quarters, etc.
	CENTER GIRDER	A vertical plate on the ship's centerline between the flat keel and inner bottom extending the length of the ship. Also called center vertical keel, CVK. Or center keelson.
	CENTER KEELSON	(See Center Girder)
	CENTER VERTICAL KEEL	(See Center Girder)
	CENTERLINE	The middle line of the ship, extending from stem to stern at any level.
CERTIFICATE OF REGISTRY	A document specifying the country the vessel is registered.
CHAFING PLATE	Bent plate for minimizing chafing of ropes
CHAIN LOCKER	A compartment for the stowage of anchor chain
CHAIN PIPE	Pipe for passage of chain from windlass to chain locker
CHAIN STOPPER	A device used to secure the chain cable when riding at anchor, thereby relieving the strain on the windlass
CHAMFER	To cut off the sharp edge of a 90 degree corner
CHOCK	A heavy smooth-surfaced fitting usually located near the edge of the weather deck through which wire ropes or fiber hawsers may be led, usually to piers
CHOCK, BOAT	A cradle or support for a lifeboat.
CLASSIFICATION SOCIETY	Independent and reputable organizations which verifies and inspects vessels for seaworthiness. As technical experts, they serve to provide the necessary basis for adjusting insurance rates for the vessel.
CLEAT	Clips at intervals on the horizontal stiffeners of hatch coamings to secure the hatch covers
COAMING, HATCH	The vertical plating bounding a hatch for the purpose of stiffening the edges of the opening and resisting water entry
COASTAL	Domestic shipping routes along the coast. (See Intercoastal and Intracoastal)
COFFERDAM	Narrow void space between two bulkheads or floors
COLLIER	Vessel used for transporting coal.
COLLISION AVOIDANCE SYSTEM	Electronic system used to prevent collisions in inland navigable waterways.
COLLISION BULKHEAD	(See bulkhead, collision.)
COMBI	Vessel designed for a combination of passengers, and different types of cargo.
COMPANIONWAY	An access way in a deck, with a ladder leading below, for the use of the crew
COMPARTMENTATION	The subdividing of the hull by transverse watertight bulkheads so that the ship may remain afloat under certain flooding conditions
CONTAINER	A strong steel box of standard dimensions of 8 feet square and length of 20 feet or 40 feet, in which cargo is preloaded.
CONTAINER SHIP	A ship designed to carry containers as cargo.
DAVIT	A crane arm for handling lifeboats, stores, etc.
DEAD RISE	Athwartship vertical rise between the keel and the bilge
DEADFREIGHT FACTOR	The amount of a ship's carrying capacity that is not utilized.
DEADWEIGHT	The total weight in tons (2240 lb.) that a ship carries on a specified draft including fuel, water in tanks, cargo, stores, passengers, baggage, crew and their effects, but excluding the water in the boilers. It is the difference in weight between a vessel when it is fully loaded and when it is empty measured by the water it displaces.
DECK	A platform in a ship corresponding to a floor in a building
DECK HOUSE	Small superstructure on the top deck which contains the steering wheel and other navigational instruments.
DECK STRINGER	The strake of deck plating that runs along the outboard edge of a deck
DECK, FREEBOARD	Deck to which freeboard is measured
DECK, WEATHER	Uppermost continuous deck and having no overhead protection having watertight openings
DEEP TANK	Tanks extending from the bottom or inner bottom up to or higher than the lowest deck
DEPTH, MOLDED	The vertical distance from the molded baseline to the top of the freeboard deck beam at side, measured at midlength of the ship
DERRICK	A device for hoisting and lowering heavy weights, cargo, stores, etc
DISPLACEMENT, LIGHT	The displacement in tons of the ship complete with all outfit, equipment, and machinery on board but excluding all fuel, water in tanks, cargo, stores, passengers, dunnage, and the crew and their effects. The light condition displacement includes the lubricating oil for the machinery and water in the boilers at steaming level. Also called light weight.
DISPLACEMENT, LOADED	The displacement of a ship when floating at her greatest allowable draft
DOUBLE BOTTOM	Compartments at the bottom of a ship between inner bottom and the shell plating, used for fresh water, ballast water, fuel oil, etc
DRAFT	The depth of the ship below the waterline measured vertically to the lowest part of the hull
DRAFT MARKS	The numbers which are placed on each side of a ship at the bow and stern from the lower edge of the number to the bottom of the keel
DRY CARGO SHIP	Vessel which carries all dry cargo
DRY DOCK	An enclosed basin used to place a ship on dry land so that all the submerged parts and fittings can be repaired.
DUAL PURPOSE SHIP	Specially designed ship for carrying different types of cargoes such as ore and/or oil.
DUNNAGE	Cushioning material placed among cargo to prevent their motion
DWT	Deadweight tons.
DWT	Deadweight Ton
ESCAPE TRUNK	A vertical trunk fitted with a ladder to permit personnel to escape if trapped
EVEN KEEL	A ship at even keel is when the keel is horizontal
FATHOM	A measure of length, equivalent to 6 linear feet, used for depths of water and lengths of anchor chain
FEU	Forty Foot Equivalent Units for Containers. See containers
FLAGS OF CONVENIENCE	Flags of nations which offer favorable tax structures and regulations. Ships registering under the laws of these nations are not always required to establish their home location in that country.
FLARE	The spreading out of the hull form from the central vertical plans, usually in the front, much like the end of a trumpet
FLOODABLE LENGTH	The length of ship which may be flooded without sinking below her safety or margin line. The floodable length of a vessel varies from point to point throughout her length and is usually greatest amidships
FLOOR	Vertical transverse plate immediately above the bottom shell plating, often located at every frame, extending from bilge to bilge.
FLUSH DECK SHIP	A ship constructed with upper deck extending throughout her entire length without a break or a superstructure, such as forecastle, bridge or poop
FORECASTLE	The raised part of the forward end of a ship's deck. It is used for the storing paints, tackle, deck stores, tarpaulins, ropes, etc.
FORWARD	The front part of a ship.
FORWARD OR FORE PERPENDICULARS	A vertical line at the intersection of the fore side of the stem and the summer load waterline (See length between perpendiculars)
FRAME	Transverse members that make up the riblike skeleton of a ship
FREEBOARD	The distance from the waterline to the upper surface of the freeboard deck at side.
FREEING PORT	An opening in the lower portion of a bulwark, which allows deck water to drain overboard
GANGWAY	A narrow hanging staircase used by persons entering or leaving a vessel from the pier or boat
GARBOARD STRAKE	The strake of bottom shell plating adjacent to the keel plate.
GENERAL CARGO	Non-bulk cargo. The cargo may be of various kinds
GIRDER	A continuous member usually running fore and aft under a deck for the purpose of supporting the deck beams and deck
GREAT LAKES SHIP	Cargo ship used to carry cargo on the Great Lakes. Most carry bulk cargoes of grain, iron ore or coal.
GROSS REGISTERED TONS	See Tonnage
GROUNDING	Contact of the bottom of a ship with the sea floor
GUNWALE BAR	(See Stringer bar)