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A small temporary weld used to hold parts in position before the final continuous weld is made.

A worker or device that makes tack welds to hold components in alignment for welding.

The transverse distance the ship's track moves after a 180-degree turn, a standard measure of turning ability under the IMO manoeuvring standards. IMO-grounded

A backup propulsion arrangement allowing a ship to proceed at reduced speed to port if the main engine fails.

An enclosed space for holding liquids such as cargo, ballast, fuel, or fresh water.

A plan showing the location, capacity, and use of all the ship's tanks, used for loading, ballasting, and operations.

The removal of cargo residues from tanks after discharge, by washing, to prepare for the next cargo or for entry, carried out under controlled procedures and, on tankers, regulated under MARPOL. IMO-grounded

Fixed or portable machines that spray water or fluid under pressure to wash the inside of cargo tanks.

A system used to verify that a cargo tank has been cleaned to the required standard.

A closure over a tank opening that maintains its integrity.

A raised section at the top of a tank, particularly on gas carriers, housing the tank's connections and fittings.

Data on the ship's tank spaces, such as capacities and contents, used in loading and stability planning.

The arrangement that supports a tank carrying hot cargo while allowing for thermal expansion and protecting the surrounding structure from heat.

A proprietary radar-based cargo-tank level gauging system, giving closed, non-contact measurement. IMO-grounded

The intended service life of a coating system before major maintenance is needed, a basis of the Performance Standard for Protective Coatings. IMO-grounded

A waterproof sheet used to cover and protect cargo or hatches.

Lighting focused on a specific work area to provide adequate illumination for the task.

A position-reference system that measures a vessel's movement relative to a weight on the seabed by a taut wire, used in dynamic positioning.

A manufacturer's document giving the properties, application, and use of a coating product.

The document recording an engine's components and settings affecting its nitrogen-oxide emissions, used to demonstrate compliance with MARPOL Annex VI and the NOx Technical Code. IMO-grounded

A submarine cable carrying communications signals, laid and maintained by cable vessels.

A heat treatment after hardening that reduces brittleness and relieves stress while retaining much of the hardness.

A pattern used to mark out or check the shape of a part during fabrication.

The maximum tensile stress a material can withstand before breaking, a basic measure of its strength.

A test in which a specimen is pulled to failure to measure properties such as tensile strength, yield, and elongation.

A facility where ships load and discharge cargo or passengers; also an electrical connection point.

The person at a terminal responsible for cargo operations and for liaison with the ship, for example during tanker loading under the ship/shore safety checklist. IMO-grounded

A small valve used to check the water level or to test for the presence of a fluid, as on a boiler gauge glass.

The speed at which a trial or test is conducted.

A submersible connected to the surface by a tether that supplies power and control, such as a remotely operated vehicle.

In a fillet weld, the theoretical depth of the weld throat used in calculating its strength.

A material's ability to conduct heat, important in insulation, heat exchangers, and structural fire protection.

The ratio of useful work output to the heat energy supplied to an engine or plant.

A bag or suit of waterproof, insulating material that reduces a survivor's heat loss in a survival craft; required equipment under SOLAS and the LSA Code. IMO-grounded

A protective device that disconnects equipment when it overheats.

A plastic that softens on heating and hardens on cooling, and can be reshaped repeatedly.

A device that automatically controls temperature by switching or modulating heating or cooling.

A solvent added to paint to reduce its viscosity for application.

A junior engineer officer, equivalent to a fourth engineer in some manning structures.

A junior deck officer, traditionally responsible for the ship's safety equipment.

An electric motor drive that gives three running speeds by changing the number of active stator poles.

A starting level or limit at which something takes effect; also the raised sill of a watertight door.

The concentration of an airborne substance to which workers may be exposed without harmful effect, used in assessing the safety of tank and cargo atmospheres.

A liferaft launched by simply throwing it overboard and then inflating it, as distinct from a davit-launched raft. IMO-grounded

The bearing that absorbs the propeller's thrust and transmits it to the hull, allowing the ship to be driven forward.

The housing containing the thrust bearing, which transfers the propeller's thrust to the ship's structure.

The power developed by the propeller's thrust acting at the ship's speed, used in propulsion analysis.

The section of shafting fitted with the thrust collar that bears against the thrust bearing.

The set of thrusters and propellers, with their controls, that hold a dynamically-positioned vessel on station and heading.

A semiconductor switching device used in power converters for electric propulsion and drives.

Energy harnessed from the movement of tides, a renewable source of relevance to certain specialised vessels and installations.

A test to confirm that a tank, joint, or closure is tight against leakage, for example by hose, air pressure, or filling.

The arm fixed to the rudder stock through which the steering gear turns the rudder.

A ro-ro ramp whose angle can be adjusted to suit the shore connection and the tide.

Wood carried as cargo, including logs and sawn lumber, which may be stowed as a deck cargo under the timber deck cargo code. IMO-grounded

Timber carried on the weather deck, whose stowage, securing, and the resulting stability are governed by the IMO Code of Safe Practice for Ships Carrying Timber Deck Cargoes. IMO-grounded

A special set of load-line marks permitting a greater draught when carrying a timber deck cargo, which adds reserve buoyancy, assigned under the Load Line Convention. IMO-grounded

A soft metal used in alloys such as bronze and solder and as a protective coating.

A strong, light, corrosion-resistant metal used for demanding components such as heat-exchanger plates handling seawater.

A thruster mounted at an angle (tilted) to direct its thrust, for example to clear the hull or improve flow.

A proprietary high-performance rudder design intended to improve steering and efficiency.

A low board along the edge of a walkway or opening that prevents tools and feet from slipping off.

A drilling-rig device that rotates the drill string from the top, suspended in the derrick, replacing the rotary table and kelly.

The final stage of filling a tank slowly to bring it to the desired level without overflowing.

The addition of more inert gas, liquid, or other material to maintain the required level or condition.

The overturning of a structure or load when it becomes unstable.

The twisting of a structural member or the hull about its long axis under torsional loads, significant for open-deck ships such as container vessels.

The oscillating twisting of a shaft or shafting system, which must be kept within safe limits to avoid fatigue failure.

The total energy of a fluid per unit weight in a system, combining pressure, velocity, and elevation, used in pump and piping calculations.

The complete loss of the insured ship or cargo, whether actual (destroyed) or constructive (beyond economic recovery).

The vertical height a pump must lift a fluid, plus any pressure difference, excluding friction losses.

The equipment used for towing, including hooks, winches, wires, and fittings.

A strong hook on a tug to which the tow line is attached, usually with a quick-release device for safety.

A device that allows a tug's towing hook to be released quickly under load to prevent the tug being girted (capsized) by the tow.

A yellow light shown above the sternlight by a vessel towing, as prescribed by the collision regulations (COLREGs). IMO-grounded

Pins on the after deck of a tug or anchor-handler that guide and restrain the tow wire or chain.

A long tank in which ship models are towed to measure resistance and study hydrodynamic behaviour.

A winch carrying the tow wire, able to pay out and recover it and to render under shock loads.

Liquids that are poisonous, requiring special precautions in handling and carriage; many are regulated as dangerous goods or noxious liquid substances under the IMDG and IBC Codes. IMO-grounded

The distance a ship travels along its original track during a crash-stop manoeuvre, a measure of stopping ability under the IMO manoeuvring standards. IMO-grounded

The continuous following of a target's position, for example by radar/ARPA, or of a vessel's progress along its route.

Guideways or rails along which equipment or cargo moves.

A highly manoeuvrable tug with its propulsion units forward of amidships, giving excellent control for ship handling.

Conventional cam-driven fuel injection, as opposed to electronically controlled common-rail systems.

A self-propelled dredger that loads dredged material into its hopper through trailing suction pipes while moving, then sails to dump or discharge it.

A ferry fitted with rails to carry railway wagons across water.

A lift used to raise and lower railway wagons between levels, for example to a train ferry.

A ship that does not operate on a fixed route or schedule but carries cargo wherever it is offered, as opposed to a liner.

An electrical device that changes the voltage of an alternating-current supply.

A trailer with a hydraulic lifting platform used to move cassettes and heavy loads in ro-ro operations.

The proportion of power delivered through the transmission (gearing and shafting) to the propeller, after losses.

A stern that ends in a flat, transverse transom rather than a rounded or cruiser form.

The carriage of bitumen and related products, which are carried hot because they are solid or highly viscous at ambient temperature.

The carriage of sulphur as a heated liquid in specially fitted tankers, requiring temperature control and ventilation.

The carriage of refrigerated containers, with power and monitoring provided for their refrigeration units.

Running across the ship, from side to side, as opposed to fore-and-aft.

The movable set of sheaves in a drilling derrick that raises and lowers the drill string, suspended from the crown block.

Fishing vessels that catch fish by towing a net (trawl) through the water or along the seabed.

A fishing method in which a net is towed to catch fish, either near the bottom or in mid-water.

A subsea machine that cuts a trench in the seabed to bury a cable or pipeline.

A ship designed to carry three different types of cargo, giving flexibility between trades.

A hull concept combining trimaran and small-waterplane-area twin-hull features for speed and seakeeping.

A proprietary integrated ship design and production software system.

A proprietary package of engine measures (cylinder liner, rings, and running-in) intended to reduce wear and lube-oil consumption.

The difference between a ship's forward and after draughts, indicating whether it is down by the head or the stern.

The approved booklet supplied to a ship giving the information needed to load it within its stability and trim limits, required under SOLAS and the Load Line Convention. IMO-grounded

The levelling and spreading of bulk cargo during loading to fill the hold and distribute the weight, important for stability and to prevent shifting.

The adjustment of a ship's fore-and-aft balance by distributing weights or ballast to achieve the desired trim.

The gathering and clearing of residual bulk cargo during discharge so that it can be reached by the grabs or discharge equipment.

A bracket fitted to a girder or stiffener to prevent it from twisting (tripping) sideways under load.

A fishing method in which baited lines are towed slowly behind a moving boat.

A vertical or horizontal enclosed passage through the ship, for example for ventilation, access, or to enclose a hatch.

An engine in which the piston transmits side thrust directly to the cylinder wall through its skirt, without a crosshead, typical of medium- and high-speed engines.

A proprietary folding structure used in cargo-handling or hatch arrangements.

A proprietary combined winch and bollard unit for mooring.

Hollow cylindrical sections used for piping, heat-exchanger surfaces, or structure.

Of tube form; tubular members are used in offshore structures and some ship components.

Powerful small vessels used to tow or push other ships and to assist them in berthing and manoeuvring.

The inward slope of a ship's sides above the waterline, so that the upper deck is narrower than the beam at the waterline.

An enclosed passage through the ship, such as a shaft tunnel or a bow-thruster tunnel.

The cloudiness of a liquid caused by suspended particles, used as a measure of water quality.

A rotary engine driven by a flow of steam, gas, or water acting on blades.

A device driven by the engine's exhaust gas that compresses the intake air to increase the engine's power and efficiency.

Disordered fluid flow with mixing and eddies, as opposed to smooth laminar flow, characteristic of most of the flow over a hull.

A ship's capacity to turn, measured by quantities such as the turning circle, advance, and tactical diameter under the IMO manoeuvring standards. IMO-grounded

The path traced by a ship's pivot point when the rudder is held at a fixed angle, used to measure turning ability. IMO-grounded

A standard manoeuvring trial in which the ship makes a full turn with the rudder hard over to measure advance, transfer, and tactical diameter, under the IMO manoeuvring standards. IMO-grounded

A device that slowly rotates the main engine for maintenance and to even out cooling, disengaged before the engine is started.

A rotating structure in a floating offshore unit to which the mooring and risers are connected, allowing the vessel to weathervane around it.

A mooring system using a turret around which a floating unit can rotate to head into the weather while staying connected to the seabed.

The turret arrangement of a floating production, storage, and offloading unit that anchors it and carries the risers while letting it weathervane.

The system within an FPSO's turret that transfers fluids between the rotating vessel and the fixed risers and moorings.

The intermediate decks between the main deck and the bottom of a hold, dividing the cargo space into levels.

Two cranes working together, for example to make a heavy tandem lift.

A hull with two skegs aft, each supporting a propeller shaft, used to improve flow and efficiency on full-form ships.

A marine evacuation system with two parallel slides allowing rapid descent of people from the ship to liferafts. IMO-grounded

A rudder whose leading edge is twisted to suit the rotational flow from the propeller, improving efficiency and reducing cavitation.

A fitting that locks into the corner castings of containers to secure them to each other and to the ship.

Coatings supplied as two parts that are mixed before use and cure by chemical reaction, giving tough, durable films such as epoxies and polyurethanes.