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Glossary of Marine Terms A-G

A - G H - M N - T U - Z  
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Marine terms, ship construction, dockyard, aft, after perpendiculars, amidships, appendages, astern, athwartship, ballast tank, barge carriers, baseline, beam cant deck molded, bilge bracket keel strake, bitter end, block coefficient, body plan, bow thrusters, breadth, breakbulk vessel, breakwater, breasthook, bridge flying house navigating, broken storage, brow, buckler, building basin, bulk cargo carrier, bulkhead deck afterpeak collision forepeak screen, bulwark, bunk, bunkers, butt strap, calk, caulk, camber, camel, cant frame, capacity plan, capstan, cargo battens port shifting, catamaran, cathodic protection, catwalk, ceiling hold tanktop joiner work, center girder keelson vertical keel, centerline, certificate of registry, chafing plate, chain locker pipe stopper, chamfer, chock boat, classification society, cleat, coaming, hatch, coastal, cofferdam, collier, collision avoidance system, collision bulkhead, combi, companionway, compartmentation, containership, davit, dead rise, deadfreight factor, deadweight, deck house, stringer freeboard weather, deep tank, depth molded, derrick, displacement light loaded, double bottom, draft marks, dry cargo ship, dock, dual purpose ship, dunnage, dwt, escape trunk, even keel, fathom, feu, flags of convenience, flare, floodable length, floor, flush deck ship, forecastle, forward fore perpendiculars, frame, freeboard, freeing port, gangway, garboard strake, general cargo, girder, great lakes ship, gross registered tons, grounding, gunwale bar

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

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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
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
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)
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.
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.
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.
GROUNDING Contact of the bottom of a ship with the sea floor
GUNWALE BAR (See Stringer bar)

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