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A private room aboard ship providing sleeping and living accommodation for crew or passengers.

Groups of electrical cables run together along common routes, supported on trays and hangers throughout the ship.

The operation of trenching and covering a submarine cable into the seabed to protect it from anchors, fishing gear, and abrasion, carried out by cable-laying vessels.

A device that guides and redirects a submarine cable during laying or repair to control its path over the ship's gear and into the water.

The specialised winches, sheaves, tensioners, and tanks aboard a cable vessel used to store, pay out, and recover submarine cable under controlled tension.

The operation of paying out and placing submarine telecommunication or power cable along a planned route on the seabed.

The notched, rotating drum on a windlass shaped to grip the links of the anchor chain so that it can be heaved in and paid out.

Locating, recovering, splicing, and re-laying a damaged section of submarine cable, performed by a cable vessel.

Equipment used to move and route cable between storage tanks and the handling gear aboard a cable-laying vessel.

A support structure, often a perforated metal channel, on which electrical cables are laid and routed through the ship.

A ship specially equipped with cable tanks and handling machinery to lay, bury, and repair submarine cables.

The carriage of cargo or passengers between two ports within the same country, trade that many states reserve for their own national flag vessels.

The checking and adjustment of an instrument against a known reference so that its readings are accurate.

A port at which a ship stops during its voyage to load or discharge cargo, embark passengers, refuel, or take stores.

The quantity of heat released by the complete combustion of a unit quantity of fuel, a key measure of a fuel's energy content.

A shaped projection on a rotating shaft that converts rotation into a precisely timed linear movement of a follower, as used to operate engine valves and fuel pumps.

The transverse curvature of a deck, higher at the centreline than at the sides, which helps water drain to the ship's side.

A floating fender or pontoon placed between a ship and a quay, or between two ships, to hold them apart and protect their sides.

The shaft carrying the cams that operate an engine's valves and fuel injection in correct sequence, driven in time with the crankshaft.

The system that supplies oil to lubricate the camshaft, its bearings, and the cam and follower contacts.

To tilt or turn something from its normal position; in structure, a cant frame is one set at an angle to the centreline, as found at the ends of a ship.

A contracted azimuthing propulsion arrangement combining a pulling propeller and a streamlined pod to improve efficiency and manoeuvring.

The amount of cargo a ship can carry, expressed by weight (deadweight) or by volume (cubic capacity), depending on the cargo type.

A plan showing the volumes and centres of gravity of all cargo, ballast, fuel, and other tank and hold spaces, used for loading and stability calculations.

The largest class of dry bulk carriers, too big for the Suez or Panama canals and so routed around the capes, used mainly for iron ore and coal.

Ships that require very large capital investment relative to their operating costs, such as highly specialised or high-technology vessels.

The overturning of a vessel so that it is no longer able to right itself, the ultimate failure of stability.

A vertical-axis powered drum used to heave on mooring or warping lines.

The officer in command of a ship, with overriding responsibility and authority for its safe navigation, the safety of those on board, the cargo, and compliance with law. IMO-grounded

Ships designed to carry large numbers of wheeled vehicles on multiple decks, loaded and discharged by driving on and off through ramps (pure car carriers and PCTCs).

A movable ramp connecting vehicle decks, or connecting a deck to the shore, allowing vehicles to be driven between levels or on and off the ship.

The vehicle decks of a car carrier or ro-ro ship, often including movable or hoistable decks to suit different vehicle heights.

Technology to capture carbon dioxide from exhaust gases and store it, being developed for ships as a means of reducing greenhouse-gas emissions.

A colourless, odourless gas produced by combustion; aboard ship it is used as a fire-extinguishing medium and is a principal greenhouse gas whose emission is being regulated under MARPOL Annex VI. IMO-grounded

A fixed fire-extinguishing system that floods a protected space such as a machinery space or cargo hold with carbon dioxide to smother a fire; its design and safety arrangements are governed by SOLAS and the FSS Code. IMO-grounded

The total greenhouse-gas emissions, expressed as carbon dioxide equivalent, attributable to a ship or activity.

A toxic, colourless, odourless gas produced by incomplete combustion, hazardous in enclosed and machinery spaces.

A shaft with universal joints at its ends that transmits drive between components that are not exactly aligned or that move relative to one another.

A navigational buoy that indicates the direction of safe water relative to a danger by reference to the cardinal points (north, east, south, west).

The four principal compass directions: north, east, south, and west.

The goods carried by a ship for freight.

The arrangement of ramps, doors, lifts, and conveyors by which cargo is moved on, off, and around a ship.

On tankers and gas carriers, the part of the ship containing the cargo tanks, cargo pump rooms, and related spaces, treated as a hazardous zone with special safety requirements. IMO-grounded

The arrangement of tanks, insulation, and secondary barriers that holds a liquefied gas cargo and keeps it at the required low temperature, designed in accordance with the IGC Code. IMO-grounded

A space from which cargo loading, discharging, and monitoring operations are supervised and controlled, particularly on tankers and gas carriers.

Cranes fitted on a ship for loading and discharging cargo without reliance on shore equipment.

Shipboard cranes used to handle cargo, allowing the vessel to work cargo at berths or anchorages that lack shore gear.

The mass of cargo a ship can carry, found by deducting the weight of fuel, stores, water, crew, and other deadweight items from the total deadweight.

The cranes, derricks, conveyors, pumps, ramps, and other gear used to load, move, and discharge cargo.

The cargo pumps, compressors, heat exchangers, and piping on a very large gas carrier used to load, discharge, and condition liquefied gas cargo.

The spaces in which cargo is loaded, stowed, or worked, including holds, decks, and associated working areas.

The opening in a deck through which cargo is loaded into and discharged from a hold, closed by a weathertight hatch cover.

A document listing all the cargo carried on a particular voyage.

A complete list of all cargo aboard a ship for a voyage, with descriptions and details, used by the carrier and customs authorities.

The set of pipe connections on a tanker or gas carrier through which cargo is loaded and discharged via hoses or shore arms.

The continuous measurement and supervision of cargo conditions such as level, temperature, pressure, and, for hazardous cargoes, atmosphere, during the voyage and cargo operations.

A plan showing how cargo is arranged in the ship, used to manage loading sequence, stability, stress, and discharge order.

An opening in the ship's side through which cargo is loaded and discharged, fitted with a watertight closing door. IMO-grounded

A space, usually below deck on a tanker, housing the cargo pumps; as a hazardous space it is subject to ventilation, gas-detection, and access safeguards under SOLAS. IMO-grounded

Guides or rails used to position and secure cargo units in their stowage, such as on vehicle or container decks.

The remnants of cargo remaining aboard after discharge, the disposal of which is regulated to prevent pollution under MARPOL. IMO-grounded

The lashings, twistlocks, chains, turnbuckles, and other fittings used to hold cargo in place against the motions of the ship.

A ship-specific manual, required for most ships under SOLAS chapter VI (and VII), describing the cargo-securing arrangements and the correct stowage and securing of cargo units, approved by the Administration. IMO-grounded

The keeping apart of cargoes that could react dangerously together or contaminate one another, required especially for dangerous goods under the IMDG Code. IMO-grounded

Spaces serving cargo operations, such as pump rooms and control rooms, as distinct from the cargo spaces themselves.

A ship engaged in carrying goods rather than passengers; the term has a specific meaning under SOLAS, which sets construction and equipment requirements for cargo ships. IMO-grounded

A statutory certificate issued under SOLAS confirming that a cargo ship's hull, machinery, and equipment meet the structural and machinery safety requirements of the Convention. IMO-grounded

A statutory certificate issued under SOLAS confirming that a cargo ship's life-saving, fire-fighting, navigational, and other safety equipment meet the Convention's requirements. IMO-grounded

A statutory certificate issued under SOLAS confirming that a cargo ship's radio installations meet the requirements for radiocommunications, including the GMDSS. IMO-grounded

Data on the cargo spaces, such as their capacities and the cargoes carried, used for planning loading and for safety.

The spaces of a ship intended for the carriage of cargo, including holds and tanks.

A tank built into a tanker or gas carrier for the carriage of liquid or liquefied-gas cargo in bulk, designed and protected in accordance with MARPOL and the relevant cargo codes. IMO-grounded

The ventilation of a cargo tank to replace its hazardous atmosphere with fresh air so that it is safe for entry and hot work, carried out under controlled procedures.

The introduction of inert gas into a cargo tank to keep the oxygen content too low to support combustion, a key safety measure on tankers required under SOLAS. IMO-grounded

A tank designed to hold liquefied gas cargo at low temperature and/or pressure, built to the standards of the IGC Code. IMO-grounded

The removal of the last residues of liquid cargo from a tank using stripping pumps or eductors after the main discharge.

The controlled release or relief of vapour from cargo tanks to manage pressure safely, through pressure/vacuum valves and venting arrangements required by the cargo codes. IMO-grounded

A discrete item of cargo or transport equipment, such as a container, trailer, or packaged item, treated as a unit for stowage and securing.

A large rotating turntable used aboard cable and flexible-pipe lay vessels to store long continuous lengths of product for controlled deployment.

The party who undertakes to carry goods by sea under a contract of carriage; also a ship type designation, as in bulk carrier or car carrier.

A coordinated protection arrangement in which electrical protective devices operate selectively so that a fault is cleared by the nearest device, limiting the extent of disconnection.

A flat load carrier onto which cargo is placed and then handled as a unit by a translifter, used in ro-ro operations.

A vehicle used in ro-ro terminals and aboard ship to lift and move loaded cassettes.

An iron-carbon alloy with high carbon content, easily cast into shape and used for components such as cylinder liners and engine parts where its wear resistance is valued, though it is brittle.

The process of forming a metal component by pouring molten metal into a mould, and the component so formed.

An accident or serious incident involving a ship, such as a collision, grounding, fire, or loss of life, the investigation of which is addressed by the IMO Casualty Investigation Code. IMO-grounded

A vessel with two parallel hulls, giving a wide, stable platform and, in fast craft, low resistance.

A sudden, large, uncontrolled escape of a hazardous cargo or substance, the prevention of which drives much of the safety design of tankers and gas carriers.

The natural curve a heavy line or chain takes when suspended between two points, important in mooring, towing, and anchor-cable behaviour.

A single-point mooring system in which a buoy is held by catenary anchor chains and a tanker moors to it to load or discharge offshore.

A proprietary impressed-current anti-fouling system that uses electrodes to protect seawater systems against marine growth.

In an electrochemical cell or corrosion process, the electrode at which reduction occurs; in cathodic protection the structure to be protected is made the cathode.

A method of preventing corrosion of steel by making it the cathode of an electrochemical cell, using either sacrificial anodes or an impressed current.

A raised, elevated walkway providing safe fore-and-aft access along a ship, notably the trunk on tankers connecting accommodation, midships, and forecastle.

The sealing of a joint or seam to make it watertight; in older construction, the driving of material into seams.

The formation and violent collapse of vapour bubbles in a liquid where the local pressure falls below its vapour pressure, notably on propeller blades, causing noise, vibration, loss of thrust, and erosion.

Erosion and pitting of a surface caused by the repeated collapse of cavitation bubbles against it, as on propellers and pump components.

The progressive loss of material from a surface due to the implosion of cavitation bubbles.

A dimensionless parameter relating local pressure to vapour pressure and flow speed, used to predict the onset of cavitation.

Model tests, usually in a cavitation tunnel, to study and predict cavitation behaviour on a propeller design.

A closed water tunnel in which pressure can be lowered, used to test model propellers for cavitation under controlled conditions.

The wood or other covering laid over the inner bottom or tank top of a hold to protect the structure and the cargo; also overhead lining in accommodation.

A bulk carrier specially fitted with pneumatic or mechanical systems to load and discharge powdered cement without dust loss.

A unit of kinematic viscosity commonly used to specify the viscosity of fuels and lubricating oils.

A space, as defined in SOLAS, in which certain control and indicating functions for safety systems are centralised, attracting specific fire-protection requirements. IMO-grounded

A cooling arrangement using a closed circuit of treated fresh water, cooled by seawater through central coolers, to serve the ship's machinery and reduce seawater corrosion in the system.

A station from which machinery and systems are monitored and controlled from one location, characteristic of ships with reduced manning of machinery spaces.

A system that maintains the suction pipework of several pumps primed from a central vacuum unit so the pumps can start promptly.

The geometric centre of the underwater volume of the hull, through which the buoyant force acts; its position is fundamental to stability.

The centroid of the waterplane area, about which a ship trims; changes of trim take place around this point.

The point through which the total weight of the ship and everything in it acts; its height (KG) is critical to stability.

The effective centre of the sideways hydrodynamic force on the hull, important in analysing turning and the balance between hull and rudder forces.

The fore-and-aft line dividing the ship into symmetrical port and starboard halves, a basic reference for design and layout.

The main longitudinal girder running along the centreline of the bottom structure, a principal contributor to longitudinal strength.

The official document evidencing a ship's nationality and registration under the flag State.

A certificate attesting that a ship is fit for the voyage and service intended, in terms of condition, equipment, and manning.

The certificates of competency and proficiency held by seafarers, issued under the STCW Convention to attest their qualifications for their roles. IMO-grounded

A person holding the appropriate certificate confirming the qualifications required for a particular duty.

A measure of the ignition quality of a diesel fuel, indicating how readily it ignites under compression; a higher number means easier ignition.

A length of chain fitted where a mooring or towing line passes over a fairlead or stopper, to take the wear instead of the rope.

Wear caused by the rubbing of one surface against another, such as a rope against a fairlead.

A plate fitted to protect structure or equipment from wear at points where ropes, chains, or cargo rub against it.

A series of connected links used for anchoring, lashing, and lifting; anchor chain in particular is sized and graded under classification rules. IMO-grounded

A means of transmitting power between shafts by a chain running over toothed sprockets, used for example to drive a camshaft.

The compartment, usually low and forward, in which the anchor chain is stowed when the anchor is hove up.

The pipe through which the anchor chain passes between the deck and the chain locker.

A device that grips and holds the anchor chain to take the load off the windlass when the anchor is secured.

The formation of a powdery layer on the surface of a paint film as the binder degrades under weathering, a normal mode of coating ageing.

The transfer of a ship's ownership, an event that typically affects the validity and continuation of insurance cover.

A rolled steel section of channel shape used as a structural stiffener or member.

The combustion air delivered to an engine under pressure by a turbocharger or blower, increasing the air available for combustion.

The act of filling or pressurising a system, such as charging an air receiver, a refrigerant circuit, or a battery.

The part of the bridge laid out and equipped for chart work and navigation planning.

A space on or adjacent to the bridge where charts and navigational publications are kept and passage planning is done.

The working position on the bridge fitted for chart work or, in modern bridges, for managing electronic charts and navigational documentation.

The contract under which a shipowner lets a ship, or part of it, to a charterer for the carriage of cargo or for a period of time.

The party who hires a ship under a charter party, whether for a voyage, a period, or on bareboat terms.

The business of hiring ships, or of letting them out, under charter parties.

A broker or agent who acts for a charterer in finding and fixing suitable tonnage.

A valve that allows flow in one direction only and closes to prevent reverse flow; also called a non-return valve.

Steel plate with a raised pattern rolled into its surface to provide a non-slip walking surface on decks and floors.

Coatings, such as two-pack epoxies and polyurethanes, that cure by chemical reaction between components rather than by simple solvent evaporation, giving tough, durable films.

Substances carried as cargo, many of which are hazardous; their bulk carriage by sea is governed by the IBC Code and, in packaged form, the IMDG Code. IMO-grounded

A mobile elevating work platform mounted on a hydraulic boom, used to lift workers to height for maintenance.

The senior engineer officer, in charge of the engine department and responsible for the operation and maintenance of the ship's machinery.

The officer next in rank to the master, head of the deck department, typically responsible for cargo operations, stability, and the maintenance of the deck.

A line where two relatively flat surfaces of a hull meet at an angle, characteristic of hard-chine planing and many small-craft hull forms.

A coating binder, now largely superseded, formerly widely used in marine and anti-corrosive paints for its chemical resistance and fast drying.

A deck fitting through which mooring or towing lines are led, guiding the line and protecting it from chafe; also a support for a stowed boat or item.

Supports shaped to hold and steady an object such as a boat, pipe, or cargo unit in place.

Cost, Insurance and Freight, a delivery term under which the seller pays the cost of the goods, marine insurance, and freight to the named destination port.

A complete path for electric current; also a planned route or round.

Protective switching devices that automatically interrupt an electrical circuit on overload or fault and can be reset, protecting equipment and cabling.

A drawing showing the components of an electrical or other system and how they are connected.

A pump that keeps a fluid moving around a circuit, such as the cooling-water circulating pump of a condenser or engine.

A protective or decorative outer layer bonded to a base material, such as a corrosion-resistant metal clad onto steel, or panelling fitted to surfaces.

A bow door that opens in two halves like a clamshell to give vehicle access on a ro-ro ship; its securing and watertight integrity are safety-critical under SOLAS. IMO-grounded

A forklift fitted with clamps instead of forks to grip and handle loads such as paper rolls or bales without pallets.

The removal of solid impurities from a liquid such as fuel or lube oil, typically by a centrifugal separator operating as a clarifier.

A centrifugal separator arranged to remove fine solids from oil, with a single outlet for the cleaned oil.

One of the stacked conical discs inside a centrifugal separator that increase the separating surface and improve clarification.

The classification assigned to a ship by a classification society, certifying that it meets that society's rules for design, construction, and maintenance. IMO-grounded

A category designation used in various standards and codes; in the context of dangerous goods, Class 1 denotes explosives under the IMDG Code. IMO-grounded

A category designation used in various standards; in dangerous-goods classification, Class 2 denotes gases under the IMDG Code. IMO-grounded

A designation used in various contexts, for example a class of AIS equipment for smaller vessels, or a category of fire-rated divisions under SOLAS. IMO-grounded

A designation used in various contexts, for example a category of fire-rated divisions under SOLAS or a grade in a classification scheme. IMO-grounded

A symbol or note in a ship's class record that records additional features, capabilities, or service restrictions certified by the classification society. IMO-grounded

A surveyor employed or authorised by a classification society to inspect ships and verify compliance with class rules. IMO-grounded

A defined term used within a classification society's rules.

The process by which a classification society develops rules and verifies, through survey, that a ship is built and maintained to them, assigning and maintaining its class. IMO-grounded

The certificates issued by a classification society confirming that a ship's hull, machinery, and equipment comply with its rules. IMO-grounded

Organisations that establish technical rules for ship design and construction and survey ships against them; recognised societies may also act for flag States in statutory work. IMO-grounded

Insulating lagging fitted around a boiler, pipe, or vessel to reduce heat loss, with an outer protective casing.

Ballast water carried in a tank that has been so cleaned that any discharge of it would not produce a visible oil trace, a concept used in MARPOL pollution-prevention requirements. IMO-grounded

A spinning glass disc set in a bridge window that throws off rain and spray by centrifugal force to keep a clear view in bad weather.

The formal permission granted by port authorities for a ship to enter or leave port once all requirements have been met.

A pin secured by spreading or riveting over its end to prevent it from working loose.

The cargo, especially oil, that remains clinging to the internal surfaces of a tank after discharge; crude oil washing reduces clingage.

A device that shows when a filter has become obstructed and needs cleaning or replacement, typically by sensing the pressure difference across it.

A survey carried out close enough to the structure, with staging or access as needed, to examine and measure structural members in detail, required for ageing ships under the survey programmes. IMO-grounded

A drainage system that conveys liquids in closed piping to a collecting tank, preventing escape of vapours or contents, used for hazardous or oily drains.

An instrument that measures the level in a cargo tank without opening it to the atmosphere, required for toxic or flammable cargoes to avoid vapour release. IMO-grounded

A tank-overflow arrangement that directs any overflow through closed piping to a designated tank rather than to the deck or sea.

Ro-ro cargo spaces that are enclosed and neither open ro-ro spaces nor weather decks; their enclosure attracts specific ventilation and fire-safety requirements under SOLAS. IMO-grounded

Enclosed spaces for the carriage of motor vehicles, subject to particular ventilation and fire-protection requirements under SOLAS because of the fire and explosion risk from fuel. IMO-grounded

A control arrangement that uses feedback of the measured output to adjust the input automatically and hold the desired condition.

The minimum distance two vessels will pass from each other if they hold their courses and speeds, a key quantity in collision-avoidance assessment computed by radar/ARPA.

A device, such as a door, hatch cover, or valve, used to close an opening and maintain watertight or weathertight integrity, as required by the Load Line Convention and SOLAS. IMO-grounded

The temperature at which wax begins to crystallise out of a fuel or oil as it cools, making it cloudy, an indicator of low-temperature handling behaviour.

A device that connects and disconnects the drive between two rotating shafts, for example between an engine and a gearbox or shaft.

A ship designed to carry natural gas under high pressure in its gaseous state, as an alternative to liquefaction, in specialised pressure containment.

A design approach for transporting natural gas as compressed gas in pressure containers aboard ship, rather than as liquefied gas.

A vessel designated to coordinate the activities of ships taking part in a surface search-and-rescue operation, following the IAMSAR procedures. IMO-grounded

A fixed system that discharges carbon dioxide to extinguish a fire by displacing oxygen, used for machinery and cargo spaces and governed by the FSS Code under SOLAS. IMO-grounded

The dedicated space housing the bank of carbon dioxide cylinders for a fixed fire-extinguishing system, arranged with safe access and ventilation.

A gas-shielded arc welding process using carbon dioxide as the shielding gas, common for welding steel.

A solid fossil fuel carried in very large quantities as dry bulk cargo; it can emit methane and self-heat, so its carriage is regulated under the IMSBC Code. IMO-grounded

A protective coating combining epoxy with coal tar, formerly widely used for ballast tanks and underwater areas for its toughness and water resistance.

A residue of coal tar distillation used in coatings and as a binder, carried as a heated cargo.

The merging of small droplets into larger ones, a process exploited in coalescer separators to remove dispersed water or oil.

A device that promotes the merging of fine droplets so that dispersed oil or water can be separated from a fluid stream.

The raised border around a hatch or other deck opening that strengthens it and helps keep water out; hatch coaming heights are set by the Load Line Convention. IMO-grounded

A drainage channel along the top of a hatch coaming that collects and leads away water from the hatch cover seals.

Waters near the coast, within which particular navigation, traffic, and environmental rules may apply.

A small cargo ship engaged in trade along a coast and between nearby ports rather than on ocean voyages.

A government vessel used for coastguard duties such as search and rescue, law enforcement, and maritime safety patrol.

A single applied layer of paint or coating; a coating system is built up from several coats.

The standards by which the condition of a protective coating is judged during inspection, for example the assessment of coatings in ballast tanks under the survey regime. IMO-grounded

The document defining the coating system to be applied, including surface preparation, products, film thicknesses, and number of coats, in line with the performance standard for protective coatings. IMO-grounded

The application of protective and decorative films to surfaces to prevent corrosion and fouling and to mark and finish them.

A simple valve with a rotating plug used to start, stop, or regulate flow.

Combined diesel and gas, a propulsion arrangement using both diesel engines and gas turbines, with diesels for economical cruising and turbines added for high speed.

A standardised numbering system for identifying the stowage position of each container aboard ship by bay, row, and tier.

The IMO code, since developed into the mandatory IMSBC Code, giving guidance on the safe stowage and shipment of solid bulk cargoes, including those liable to liquefy or to present chemical hazards. IMO-grounded

A propulsion arrangement combining diesel engines and diesel-electric drive to optimise efficiency across the operating range.

A numerical factor expressing a property or relationship, widely used in naval architecture (for example the coefficients of hull form).

The ratio of the area of the waterplane to the area of its enclosing rectangle, indicating how full or fine the waterplane is.

The set of non-dimensional ratios, such as block, prismatic, midship, and waterplane coefficients, that describe the fullness and character of a hull form.

A narrow empty space separating two compartments to prevent contents passing between them, for example isolating cargo tanks from accommodation or machinery spaces, as required on tankers. IMO-grounded

Combined gas turbine and steam, an electric-generating arrangement in which a gas turbine's exhaust heat raises steam in a boiler to drive a steam turbine generator, improving overall efficiency.

Decks or cradles shaped to stow steel coils securely, preventing them from rolling and spreading their heavy concentrated loads.

The practice of shutting down a ship's own generators in port and drawing electrical power from a shore connection, reducing emissions and noise in port; also called shore power.

Refrigerated spaces aboard ship for carrying perishable cargo or for ship's provisions.

Work on metal carried out without applying heat, and, in tanker operations, any work that does not involve a source of ignition, as distinct from hot work.

A mast designed to be lowered or folded, for example to reduce air draft for passing under bridges.

A plate fitted to close the gap where a stiffener or pipe passes through a structural member, maintaining the continuity and tightness of the structure.

The striking together of two vessels; the prevention of collisions at sea is governed by the international collision-avoidance rules (COLREGs). IMO-grounded

The foremost main transverse watertight bulkhead, positioned to limit flooding if the bow is damaged; its location and strength are required by SOLAS. IMO-grounded

Structural damage resulting from a collision, and the standard against which a ship's ability to survive such flooding is assessed in damage stability. IMO-grounded

The International Regulations for Preventing Collisions at Sea, the IMO rules governing the conduct of vessels, lights, shapes, and sound signals to prevent collisions. IMO-grounded

A ship designed to carry either dry bulk or liquid bulk cargoes, such as an ore/bulk/oil carrier, giving flexibility between trades.

A power arrangement that recovers waste heat from a prime mover, such as a gas turbine, to generate additional power in a steam cycle, raising overall efficiency.

A propulsion system that combines diesel (often diesel-electric) drive with gas turbines, using the diesels for cruising and adding turbine power for high speed.

An instrument that measures the concentration of flammable gas in an atmosphere, used to check that spaces are safe before entry or hot work.

Capable of catching fire and burning; flammable and inflammable both mean readily ignitable.

A system that humidifies an engine's combustion air with water to reduce the formation of nitrogen oxides during combustion.

An unobstructed, wide field of view, such as that required from the bridge for the safe navigation and manoeuvring of the ship.

Devices that grind sewage solids into small particles as part of a sewage treatment or discharge system, the discharge of sewage being regulated under MARPOL Annex IV. IMO-grounded

A bulk raw material or primary product traded in large quantities, such as oil, grain, ore, or coal.

A fuel-injection system in which fuel is held at high pressure in a common manifold (rail) and injected into each cylinder under electronic control, allowing flexible, precise injection independent of engine speed.

The bridge position equipped with the radio and communication equipment, including the GMDSS installation, for ship's communications. IMO-grounded

In a direct-current machine, the switching of current between armature windings by the commutator to maintain a steady output.

A smaller version of the podded electric propulsion unit, providing combined propulsion and steering for medium-sized vessels.

Equipment that compresses waste to reduce its volume for storage and disposal, the handling of garbage being regulated under MARPOL Annex V. IMO-grounded

A stairway or ladderway leading from one deck to another within a ship, and its access opening.

In safety-management terms, the owner of the ship or any organisation that has assumed responsibility for its operation and the duties under the ISM Code. IMO-grounded

The person designated by the company under the ISPS Code to be responsible for the ship security assessment, the ship security plan, and liaison with ship and port security officers. IMO-grounded

A space within a ship bounded by decks and bulkheads.

The division of a ship into separate compartments by watertight bulkheads and decks to limit flooding and contribute to damage survivability. IMO-grounded

An instrument for determining direction; the magnetic compass senses the Earth's field, while the gyrocompass indicates true north by gyroscopic action. IMO-grounded

The process of measuring and correcting the deviation of a magnetic compass caused by the ship's own magnetism, and recording the residual deviations.

Whether cargoes can be carried or stowed together without dangerous reaction or contamination, a key consideration for chemicals and dangerous goods. IMO-grounded

The full number of officers and crew that make up a ship's company.

A boiler that can be fired by its own burner and also use exhaust gas from the engine to raise steam, suiting both at-sea and in-port operation.

A bar against which a hatch-cover gasket is compressed to form a weathertight seal.

An engine, such as the diesel, in which fuel injected into air compressed and heated in the cylinder ignites spontaneously without a spark.

The ratio of the cylinder volume at the start of compression to that at the end, a key parameter governing an engine's efficiency and ignition.

The numerical simulation of fluid flow, used in ship design to predict resistance, flow around the hull and propeller, and other hydrodynamic behaviour.

A folding door that opens and closes like a concertina, used where space for a swinging door is limited.

A voluntary, in-depth assessment of the actual condition of a ship, often older tankers, going beyond minimum class requirements and resulting in a graded rating. IMO-grounded

A mandatory survey and verification regime under MARPOL Annex I that assesses the structural condition of certain older oil tankers to confirm their fitness for continued service. IMO-grounded

A maintenance strategy in which equipment is serviced based on its actual measured condition, using monitoring, rather than at fixed intervals.

A survey to establish the current physical condition of a ship or its structure, often for a specific purpose such as sale, insurance, or assessment of an older vessel.

A measure of a material's ability to conduct electricity or heat; in water treatment, electrical conductivity indicates dissolved-solids content.

A space with limited entry and exit and inadequate natural ventilation that may contain a hazardous atmosphere; entry requires strict precautions under IMO guidance and SOLAS enclosed-space requirements. IMO-grounded

The rod that links the piston to the crankshaft, converting the piston's reciprocating motion into rotation.

A bridge display that brings together the key navigation and manoeuvring information needed to con the ship in one view.

A laboratory measure of the carbon residue left after a fuel oil is burned under controlled conditions, indicating its tendency to form deposits.

The party named to receive the cargo at the destination.

A unit housing instruments and controls grouped together for an operator, as on the bridge or in machinery control rooms.

A vessel or module configured to support offshore construction and maintenance work, carrying the necessary equipment and personnel.

Heavy-lift cranes fitted on offshore construction vessels to install and maintain subsea and platform structures.

Offshore vessels equipped to support installation, construction, and maintenance work at sea, typically with cranes, deck space, and dynamic positioning.

In marine insurance, a loss where the ship or cargo is so damaged that the cost of recovery and repair would exceed its value, allowing the insured to claim as for a total loss.

Items used up in the course of operation, such as fuel, lubricants, stores, and spare parts.

In insurance and casualty terms, a vessel's striking of a fixed or floating object other than another ship or the seabed.

Damage caused by a ship coming into contact with a fixed or floating object such as a quay or buoy.

An electrically operated switch for repeatedly making and breaking a power circuit, used to control motors and other equipment.

A standardised reusable box for carrying cargo, designed for intermodal transport and built and tested to international standards under the CSC Convention. IMO-grounded

A group of containers stowed together as a unit within the ship's stowage plan.

Vertical steel guides in a container ship's holds that locate and restrain containers as they are stacked, holding the stack in place.

A manual approved for a container ship describing the systems and procedures for securing containers and the permissible stowage and lashing arrangements. IMO-grounded

A vertical pile of containers stowed one above another, in a hold or on deck.

The loads imposed by a stack of containers, including the weight carried by the lowest container and the forces from ship motions, which the securing system must withstand.

The arrangement of containers within the holds, guided by cell guides, which provide restraint against the ship's motions.

The arrangement of containers carried on deck, secured by lashings and twistlocks and subject to limits on stack height and weight.

A port facility designed for the efficient handling, storage, and transfer of containers between ships, road, and rail.

The system of carrying general cargo in standardised containers, which transformed cargo handling by enabling fast, intermodal transport.

A document required under SOLAS that provides an onboard record of a ship's history, including flag, owners, classification society, and ISM/ISPS details, kept up to date through the ship's life. IMO-grounded

A weld run made along the whole length of a joint without breaks, as opposed to an intermittent weld.

An arrangement of two coaxial propellers turning in opposite directions, the after one recovering rotational energy from the forward one to improve propulsive efficiency.

The means by which the operation of machinery or a process is directed and regulated.

Spaces containing the ship's radio, main navigating equipment, central controls for safety systems, or the emergency source of power; SOLAS gives them particular fire-protection requirements. IMO-grounded

The combination of sensors, controllers, and actuators that regulates a machine or process to achieve and maintain the desired conditions.

A valve whose opening is adjusted, often automatically, to regulate the flow of a fluid in a control system.

The deliberate adjustment of the gas composition in a cargo space, for example to slow the ripening of fruit or to reduce fire risk, by controlling oxygen and other gases.

The equipment that establishes and maintains a controlled gas composition in a refrigerated or protected cargo space.

A cargo-tank venting arrangement that controls the release of vapour through pressure/vacuum valves to maintain safe tank pressure, as required by the cargo codes. IMO-grounded

Traditional single-component paints that dry mainly by solvent evaporation or air oxidation, as distinct from chemically curing high-performance coatings.

A device that changes the form of electrical power, for example between alternating and direct current or between frequencies, used in electric propulsion and power systems.

A system of belts or other moving elements that transports bulk cargo continuously, used in self-unloading ships and terminals.

A group of ships travelling together, historically for mutual protection.

A heat exchanger that removes heat from a fluid, such as a lubricating-oil or charge-air cooler.

The gradual lowering of the temperature of a cargo tank and system before loading a cold liquefied gas, to avoid thermal shock to the structure.

A metal of high electrical and thermal conductivity used for electrical conductors and, in alloys, for heat-exchanger tubes and fittings.

A proprietary panel product used in shipboard construction, for example for linings or insulation.

A welded joint between two members meeting at approximately a right angle to form a corner.

A reinforcing or protective pad fitted at the corner of a structure or cargo unit to spread load or prevent damage.

The deterioration of metal by chemical or electrochemical reaction with its environment, a major cause of structural degradation in ships, countered by coatings, cathodic protection, and corrosion allowances.

The accelerated cracking of a metal under the combined action of cyclic stress and a corrosive environment, more severe than either acting alone.

The combination of measures used to protect a ship against corrosion, including protective coatings and cathodic protection, with coating performance standards required by SOLAS for certain tanks. IMO-grounded

The speed at which metal is lost to corrosion, often expressed as thickness lost per year, used in assessing structural condition and remaining life.

Liquids that attack and degrade materials they contact, requiring resistant materials and careful handling; many are regulated as dangerous goods. IMO-grounded

Formed into a series of parallel folds or ridges, which greatly increases the stiffness of plating; used for bulkheads and hatch covers.

Bulkheads formed from corrugated plating, which provides stiffness without separate stiffeners, commonly used in tankers and bulk carriers.

A proprietary device used to recover a person from the water back aboard a vessel during a man-overboard situation.

A proprietary compressed-natural-gas containment system in which gas is stored in large coiled pipe (the coselle) for transport by sea.

The direction in which a ship is steered, expressed as a compass heading.

A ship's ability to maintain a steady straight course with minimal corrective steering, an important aspect of manoeuvring performance.

A hood-shaped cover fitted to a ventilator or funnel to direct airflow or keep out rain and spray.

The person who steers and is in charge of a boat, particularly a ship's lifeboat or a small craft.

A fracture or fissure in material, which if it grows can threaten structural integrity; detection and repair of cracks is a focus of survey.

A design feature, such as a tougher strake of steel, intended to stop a running brittle crack from propagating through the structure.

The defining performance figures of a crane, such as its safe working load, outreach, lifting height, and slewing capability.

Vessels fitted with very heavy-lift cranes for offshore installation, salvage, and construction work.

A self-contained crane installation, including its structure, machinery, and controls, fitted to a vessel.

Lifting machines used aboard ship and in ports to raise, move, and lower loads.

The arm on a crankshaft that, with the crankpin, converts reciprocating motion into rotation.

The radial distance from the crankshaft axis to the crankpin centre, which determines the engine's stroke.

The enclosure that houses the crankshaft and contains the lubricating oil at the base of an engine.

An explosion of an oil-mist and air mixture within the crankcase, typically triggered by a hot spot; guarded against by oil-mist detection and relief valves.

A valve fitted to the crankcase that opens to relieve the pressure of an internal explosion and prevent the casing from bursting, then reseals to keep out air.

The journal of the crankshaft to which the big end of the connecting rod is fitted.

The main rotating shaft of a reciprocating engine that converts the linear motion of the pistons, through the connecting rods, into rotation.

The measurement of the small changes in the gap between crank webs as the shaft is turned, used to check shaft alignment and bearing condition.

The variations in crank-web spacing that indicate misalignment of the crankshaft and its bearings.

An emergency manoeuvre in which the engine is reversed at full power to stop the ship as quickly as possible, the stopping distance being a measure of manoeuvrability.

The depression left at the end of a weld run where the arc was broken, which must be properly filled to avoid cracking.

Localised corrosion that occurs in narrow gaps and crevices where a stagnant, oxygen-depleted environment forms, common under deposits and at joints.

The personnel employed aboard a ship to operate it; manning levels are subject to safe-manning requirements under SOLAS. IMO-grounded

The official list of all crew members aboard a ship, used by port and immigration authorities.

Failure by the crew to exercise reasonable care, a concept relevant to liability and marine insurance.

A fast vessel used to carry personnel and supplies to and from offshore installations.

A fast craft used mainly to transport personnel to and from offshore platforms and vessels.

The load at which a structure becomes unstable or fails, such as the buckling load of a member.

Locations in the hull where stresses are high or fatigue and cracking are likely, which receive particular attention during design and survey.

The temperature above which a gas cannot be liquefied by pressure alone; also, in metallurgy, a temperature at which a phase change occurs.

A set of curves giving a ship's righting-arm values at various displacements for a range of heel angles, used to construct stability curves for any loading.

The transverse deck structure connecting the two sides of a ship, for example between the hulls of a catamaran or across the hatch openings of a container ship.

Structural members spanning across a tank or hold to tie opposite sides together and resist the loads on the structure.

The deliberate flooding of compartments on the side opposite to damage to reduce heel and restore a more upright, survivable condition after damage. IMO-grounded

The ducts and fittings provided to allow water to flow across the ship to balance asymmetric flooding within the time required by the damage-stability rules. IMO-grounded

Bolts that secure adjacent hatch-cover panels together at their cross joints.

A channel at the joint between hatch-cover panels that collects and drains away any water that passes the seals.

A transverse beam tying structural members together across a space to share and resist loads.

In a large two-stroke engine, the sliding block connecting the piston rod to the connecting rod, which takes the side thrust and keeps it off the piston.

The bearing at the crosshead connecting the piston rod and connecting rod, operating with an oscillating rather than rotating motion.

The fixed set of sheaves at the top of a drilling derrick over which the drilling line is rove.

A propulsion arrangement combining a conventional propeller with a contra-rotating podded unit behind it to recover energy and improve efficiency.

Unrefined petroleum as extracted, the principal cargo of crude tankers; its carriage and the prevention of oil pollution are governed by MARPOL Annex I. IMO-grounded

A tanker designed to carry crude oil in bulk, subject to MARPOL requirements including segregated ballast, crude oil washing, and the condition assessment scheme for older ships. IMO-grounded

The fixed tank-cleaning machines that spray crude oil under pressure to wash the cargo tanks during discharge.

A tank-cleaning method in which the cargo's own crude oil is sprayed to wash clingage from the tank walls, reducing residues and pollution; it is required for larger crude tankers under MARPOL Annex I and is carried out under controlled, inerted conditions. IMO-grounded

A passenger ship combining ferry transport with cruise-style accommodation and facilities, carrying passengers and often vehicles on scheduled routes.

A passenger ship designed for leisure voyages, with extensive accommodation and amenities; such ships are subject to the full range of SOLAS passenger-ship safety requirements. IMO-grounded

A rounded, overhanging stern form that extends the waterline aft and provides good flow and reserve buoyancy.

The IMO Code of Safe Practice for Cargo Stowage and Securing, which gives guidance on the proper stowage and securing of cargoes other than bulk cargoes. IMO-grounded

The progressive accumulation of fatigue damage in a structure under repeated loading, leading eventually to cracking.

The process by which a coating or resin hardens and develops its final properties, by chemical reaction or other means.

The time a coating or adhesive needs to harden fully and reach its intended performance.

The horizontal movement of seawater, important for navigation and ship handling; also the flow of electric charge.

A curve giving the least metacentric height that must be maintained at each draught to satisfy the ship's stability requirements throughout operation. IMO-grounded

A curve showing how the resistance of the hull increases with speed, used in determining the power required.

A curve showing the righting arm against angle of heel, from which a ship's stability characteristics, such as range and maximum righting arm, are read; it must satisfy intact stability criteria. IMO-grounded

A curve showing the immersed cross-sectional area of the hull along its length, describing the longitudinal distribution of volume.

A curve giving the highest position of the centre of gravity permitted at each draught for the ship to meet its stability criteria. IMO-grounded

A curve showing how the height of the centre of buoyancy varies with draught.

A curve showing how the area of the waterplane changes with draught, used in hydrostatic calculations.

A curve showing the distribution of the ship's weight along its length, used with the buoyancy distribution to find the loads on the hull girder.

A dredger that loosens seabed material with a rotating cutter head and pumps the resulting slurry through a pipeline by suction.

The rotating toothed head at the end of a cutter-suction dredger's ladder that breaks up compacted seabed material for removal.

A power converter that produces a variable low-frequency alternating output directly from a fixed-frequency supply, used in some electric propulsion drives.

A propulsion unit with vertical blades rotating about a vertical axis whose pitch is varied to direct thrust in any horizontal direction, giving excellent manoeuvrability (the Voith Schneider type).

The bore in which an engine's piston moves, where combustion takes place; also a vessel for storing compressed gas.

The main casting or structure containing an engine's cylinders.

The component closing the top of a cylinder, carrying the valves and injector and forming the combustion chamber.