Maritime Dictionary
Aft: At, or towards the stern of a vessel. (Opposite to forward.)
Aft peak tank: A tank or compartment located abaft the aftmost watertighttransverse bulkhead above propeller(s) and rudder (often used forfresh water or sea water ballast).
Alleyway: A vessel’s internal passageway or corridor.
Alongside: The position of a vessel when securely moored on a berth in port.
Amidships: (1) Midway (midpoint) between port and starboard sides of avessel. (2) The midway point between the forward and aftperpendiculars.
Anchor: A heavy steel device (of variable design) so shaped as to grip thesea bed to hold a vessel or offshore installation in a desiredposition.
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Anchor |
Anchor cable: Chain or wire connecting a vessel to its anchor(s).
Antifouling (paint): A marine paint composition containing toxic ingredients preventingor retarding marine underwater growth on the hull of a vessel.
Appendage(s): Objects protruding from the underwater section of a hull; e.g., bilgekeels, rudders, stabilising fins, shaft brackets, etc.
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stabilising fins |
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rudders |
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shaft brackets |
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bilgekeels |
Astern: The backward direction in the line of a vessel’s centreline.
Ballast: Liquid or solid mass loaded by a vessel to improve stability andtrim characteristics and to increase propeller immersion.Temporary ballast is usually sea water stored in dedicated tanks.Permanent ballast (if required) is usually solid lead castings.
Baseline: A horizontal and longitudinal datum (reference) line, usually takenat the inner surface of the keel plating, to which all verticalmeasurements are referred.
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Baseline |
Beam: (1) The registered breadth of a vessel, measured at the outside ofthe hull amidships, or at its greatest breadth. (2) A transversestructural member supporting a deck and/or strengthening a hull.
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Beam |
Bed plate: The upper surface plating of a foundation platform of an engine ordeck installation to which that equipment or machinery ispermanently attached.
Berth: (1) A location in which a vessel is moored or secured alongside awharf. (2) Allotted accommodation in a vessel.
Bilge: (1) Intersection or curved transition of bottom and sides of a hull.(2) Lowest points within hull compartments where liquids mayaccumulate.
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Bilge |
Bilge bracket: Vertical transverse plate located beneath side frames in the area ofthe bilge and between inner and outer bottoms.
Bilge keel: Non-retractable elongated longitudinal fin protruding from thebilge used to reduce rolling.
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Bilge keel |
Bilge strake: Line of shell plating at the bilge between bottom and side plating.
Bitts: Twin stout posts welded to the deck to which mooring lines arefastened.
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Bitts |
Body plan: Drawing consisting of 2 end views of a hull showing cross-sectionform, deck line curvature, and projections (as straight lines) ofwaterlines and buttock lines.
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Body plan |
Bollard: The equivalent of a vessel’s mooring bitts used onshore.
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Bollard |
Boot-topping: Durable paint coating applied to a hull between the light andloaded waterlines.
Bossing: Hydrodynamically faired outboard portion of hull platingsurrounding and supporting propeller shafting. In a single-screwvessel the bossing is integral to a centreline skeg.
Bow:The forward end or region of a hull.
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Bow |
Bow door: Watertight hinged door in the fore end of a Ro-Ro vessel throughwhich vehicles and cargo may be loaded or discharged.
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Bow door |
Bow thruster: A propulsor installed near the bow to provide a transverse thrustcomponent enhancing manoeuvrability.
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Bow thruster |
Bracket: Plate used to rigidly connect 2 or more intersecting structuralmembers.
Breadth: Beam or width of a hull or superstructure.
Breasthook: Horizontal plate brackets of generally triangular form connectingport and starboard side stringers and bow plating at the stem.
Bridge: Elevated centre dedicated to the control and navigation of thevessel. [Alt. Navigating bridge or wheelhouse.]
Bridge wing(s): Lateral (open or enclosed) extension(s) to a vessel’s bridge topermit direct vision beyond the hull side.
Bulk cargo: Cargo shipped in loose condition and of a homogeneous nature.
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Bulk cargo |
Bulk carrier: Vessel designed for the transportation of dry loose homogeneouscargoes in bulk in self-trimming holds and constructed to sustainthe heavy concentrated weight distribution of the cargoes.
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Bulk carrier |
Bulkhead: (1) A vertical structural partition dividing a vessel’s interior intovarious compartments for strength and safety purposes; (termedstrength bulkhead). (2) Term applied to vertical partition walls(non-structural) subdividing the interior of a vessel intocompartments.
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Bulkhead |
Bulkhead deck: Uppermost deck at which transverse watertight bulkheadsterminate.
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Bulkhead deck |
Bulwark: Barrier of stiffened plating at the outboard edge of the main orupper deck to prevent or inhibit entry of the sea. Bulwarks may beadditionally employed at the forward edges of superstructure decksin lieu of safety railings as a barrier to wind and spray.
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Bulwark |
Cable layer: Vessel designed for the laying and repair of seabedtelecommunicationcables.
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Cable layer |
Cable locker: Compartment located forward to store the anchor cable.
Camber : Transverse convex curvature of exposed decks to accelerate runoff.
Cant frame: Hull side frame not aligned perpendicular to the vessel’s centreline.
Capstan: Steelwarping drum rotating on a vertical axis for the handling ofmooring lines and optionally anchor cable.
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Capstan |
Car carrier: Vessel designed for the delivery transportation of road vehicles.
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Car carrier |
Cargo door: Watertight door in the hull side through which cargo may be loadedor discharged.
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Cargo door |
Cathodic protection: Sacrificial or impressed current system of corrosion protection ofhull, tanks and piping.
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Cathodic protection |
Container vessel: Vessel designed specifically for the transportation of standard sizecontainers within the hull and on deck.
Cellular container ship: Container vessel having specially designed vertical cell guides forthe accommodation of standard size containers thereby precludingmovement and lashing.
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Cellular container ship |
Centreline: The longitudinal vertical plane of a vessel.
Chemical carrier (Tanker): Vessel designed specifically for the transportation of volatile,poisonous or corrosive liquids in specially constructed tanks.
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Chemical carrier (Tanker) |
Classification societies: Organisations which set standards for design and construction ofvessels and integral machinery amongst much else.
Coaming: Raised rim of vertical plating around a hatchway to prevententrance of water, the upper edge of which forms a sealing surfacewith the hatch-lid or cover.
Cofferdam: Narrow compartment (void space) between 2 transverse bulkheadsor floors, to separate incompatible contents or spaces.
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Cofferdam |
Collision bulkhead: The forward-most transverse watertight bulkhead ranging from thebottom of the hull to the bulkhead deck to prevent flooding ofcompartments aft in the event of collision.
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Collision bulkhead |
Compartment: Enclosed space usually with watertight bulkheads, doors orhatches.
Counter: The overhanging stern section of a hull extending abaft the aftperpendicular or propeller aperture.
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Counter |
Davit(s): Radial or hinged or telescopic launch/recovery and housinginstallations for survival craft.
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Davit(s) |
Deadlight:Steel or alloy cover plate fitted internally to portholes forprotection against water ingress in case of glass failure.
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Deadlight |
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Deadlight |
Deadrise: Transverse inclination of the hull bottom from keel to bilge. [Alt:rise of floor.]
Deck height: Vertical distance between moulded lines of 2 adjacent decks. [Alt:deck interval.]
Deep tank: Tank (usually for fuel) having significant depth (typically spanningmore than 1 deck interval).
Derrick: Obsolete form of lifting appliance employing a hinged boom, kingpost(s) and running wires for control.
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Derrick |
Diesel generator: Alternator (generator) directly powered by a diesel prime moverproducing AC electrical power.
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Diesel generator |
Displacement: All-inclusive mass or weight of vessel measured in tonnes, andequal to the mass of water displaced.
Docking plan: Detailed structural plan and profile of the lower hull structurerequired for correct location of the vessel in dry docking.
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Docking plan |
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Docking plan |
Double bottom: Structural configuration employing a complete watertight innerbottom deck above the hull bottom plating, extending from thecollision bulkhead to the aftmost watertight bulkhead.
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Double bottom |
Draft(or draught): Depth to which a hull is immersed.
Draft marks: Numbers marked on the hull side forward, aft (and amidships onlarge vessels) indicating the draft.
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Draft marks |
Dredger: Vessel designed for the removal of sea bed alluvial sediment.
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Dredger |
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Dredger |
Drill ship: Vessel designed for sea bed drilling operations.
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Drill ship |
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Drill ship |
Dry bulk: Cargo shipped in a dry state and in bulk; e.g., grain, cement.
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Dry bulk |
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Dry bulk |
Dry dock: (1) Large basin with sealing caisson for the repair and maintenanceof vessels. (2) General term for basin dry docks, floating docks orlift platforms for the maintenance and repair of vessels.
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Dry dock |
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Dry dock |
Duct: Vertical or horizontal large cross-section conduit through whichpiping, cabling, or fluids may be conducted.
Duct keel: Longitudinal passage within the double bottom, usually on thecentreline, extending from the collision bulkhead to the engineroom, through which ballast, bilge, fuel and hydraulic piping maybe conducted and providing access to double-bottom spaces.
Electro-hydraulic: Term given to hydraulic actuation systems where the hydraulicpressure is produced by electrically driven pumps and controlledvia solenoids.
Endurance: Maximum time period (indicated in hours or days) that a vessel canoperate unreplenished while performing its intended role.
Engine control room: Space adjacent to engine room from where engine room systemsmay be controlled and monitored.
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Engine control room |
Engine room: Primary machinery space containing a vessel’s propulsion primemovers.