I

A type of radar or sensor display format.

Structural sandwich panels with internal I-shaped stiffeners between two face plates, giving high stiffness and a smooth surface.

The International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk, the IMO code, mandatory under SOLAS and MARPOL, setting the standards for chemical tankers. IMO-grounded

Frozen water, which presents navigation hazards and structural and stability dangers (such as topside icing) for ships operating in cold regions, addressed by the Polar Code. IMO-grounded

A band of strengthened and thickened shell plating around the waterline of an ice-going ship to resist the loads from ice.

A classification notation indicating a ship's capability to navigate in ice of a given severity, with corresponding strengthening and power requirements. IMO-grounded

The rules, such as the Finnish-Swedish ice class rules and classification-society requirements, defining the structure, power, and equipment for ships of each ice class.

The reinforcement of a ship's hull, rudder, and propeller to withstand the loads imposed by navigation in ice.

A ship specially designed and powered to break through ice to keep channels open and escort other vessels.

A podded propulsion unit designed and strengthened for operation in ice.

The accumulation of ice on a ship's exposed structure from freezing spray or precipitation, which raises the centre of gravity and endangers stability, allowed for in stability criteria for ships in cold areas. IMO-grounded

A small symbol on a display representing a function or object.

The starting of combustion, by spark, heat, or compression; controlling ignition sources is central to fire and explosion safety.

The short interval between the injection of fuel and the start of combustion in a diesel engine, which affects combustion quality and knock.

The amount of light falling on a surface, important for safe working and is specified for various spaces aboard ship.

The state of being under water; also the depth to which a body sinks.

A waterproof insulated suit that protects a person against hypothermia in cold water, required as life-saving equipment under SOLAS and the LSA Code. IMO-grounded

The International Maritime Organization, the United Nations agency responsible for the safety and security of shipping and the prevention of marine and atmospheric pollution by ships. IMO-grounded

The conventions, codes, protocols, and resolutions adopted by the IMO that set international standards for shipping, such as SOLAS, MARPOL, STCW, and the Load Line Convention. IMO-grounded

The rotating bladed element of a centrifugal pump or compressor that imparts energy to the fluid.

A corrosion-protection system that passes a controlled direct current from anodes to the hull to keep the steel cathodic and prevent it from corroding.

A survey of a ship's underwater hull carried out by divers or remote means while the ship is afloat, accepted in place of drydocking for certain ships under the survey regime. IMO-grounded

Equipment deployed and operated in the sea, such as towed arrays, sensors, or subsea tools.

A test, required for new and significantly altered ships, in which known weights are shifted across the deck and the resulting heel is measured to determine the ship's lightship weight and centre of gravity for stability calculations. IMO-grounded

A localised inward deformation of plating caused by impact or contact.

Describing a system or tank that functions on its own, not relying on or connected to others; see independent tank.

A cargo tank that is self-supporting and does not form part of the ship's hull, used on gas carriers and built to the categories of the IGC Code. IMO-grounded

Self-supporting cargo tanks built separately from the hull structure, classified by type under the IGC Code for gas carriers. IMO-grounded

The power developed in an engine's cylinders by the combustion gases, calculated from the indicator diagram, before mechanical losses.

A plot of cylinder pressure against volume or crank angle, used to assess an engine's combustion and to calculate its indicated power.

A refrigeration arrangement in which the refrigerant cools a secondary fluid (such as brine) that is circulated to cool the spaces, keeping the refrigerant within the machinery space.

A tank-level instrument that measures the level without direct contact with or exposure of the cargo, used for hazardous cargoes. IMO-grounded

A diesel engine in which fuel is injected into a pre-combustion or swirl chamber rather than directly into the main cylinder.

Vessels built to perform an industrial function at sea, such as dredgers, cable layers, and offshore units, rather than to carry cargo or passengers.

The state of a cargo tank whose atmosphere has been made non-flammable by reducing its oxygen content with inert gas. IMO-grounded

Gas with too little oxygen to support combustion, introduced into cargo tanks to prevent flammable atmospheres; inert-gas systems are required on tankers under SOLAS. IMO-grounded

The fan that delivers inert gas from the generator or flue-gas plant to the cargo tanks.

A unit that produces inert gas by burning fuel under controlled conditions, used where boiler flue gas is not available or suitable, to inert cargo tanks. IMO-grounded

The complete system that produces, cools, cleans, and delivers inert gas to the cargo tanks to keep their atmospheres below the flammable range; required on tankers under SOLAS. IMO-grounded

The introduction of inert gas into a space to lower its oxygen content below that needed for combustion, a key safety measure on tankers and gas carriers. IMO-grounded

Liquids that readily catch fire; the term means the same as flammable liquids, which are regulated as dangerous goods. IMO-grounded

A life-saving appliance, such as a liferaft, that is inflated for use; required types and standards are set under SOLAS and the LSA Code. IMO-grounded

A life-saving appliance kept permanently inflated and ready for use, as distinct from one inflated when deployed.

A ship's natural tendency, without corrective steering, to continue on a straight course rather than to diverge, an aspect of its manoeuvring behaviour.

Substances added to slow an unwanted reaction, such as corrosion inhibitors in cooling water or polymerisation inhibitors in certain chemical cargoes.

A measure of how quickly a ship begins to change heading when the rudder is applied, part of the standard assessment of manoeuvrability. IMO-grounded

The forcing of fuel into an engine's combustion chamber, or of a substance into a system, under pressure.

The valve that injects atomised fuel into an engine cylinder at the correct time and pressure.

A satellite communication system providing maritime mobile services, including distress and safety communications recognised within the GMDSS. IMO-grounded

The plating forming the top of the double bottom, on which cargo rests in the holds and which provides a second barrier against bottom damage.

The inner watertight boundary of a double-hull ship, separated from the outer shell by ballast or void spaces to protect the cargo tanks against side damage. IMO-grounded

A plate of greater thickness or higher grade let into the surrounding plating at an area of high stress, such as around an opening.

Corrosion that is light and within acceptable limits, requiring monitoring but no immediate repair.

An offshore vessel equipped to inspect, maintain, and repair subsea installations, typically using remotely operated vehicles and cranes.

The rate at which oil is being discharged with an effluent at any moment, monitored and limited under MARPOL Annex I to control operational oil pollution. IMO-grounded

A device for measuring, indicating, or controlling a quantity.

Clean, dry compressed air supplied to operate pneumatic instruments and control equipment.

The collection of instruments and sensors used to measure, monitor, and control a ship's machinery and systems.

A freight container with insulated walls to limit heat transfer, used for cargoes needing temperature protection.

A tank container with insulation, used to carry liquids that must be kept hot or cold.

A pipe flange fitted with insulating material to break electrical continuity, used to control galvanic corrosion or stray currents.

Material used to limit the transfer of heat, cold, sound, or fire, applied to structures, pipes, and spaces; fire-insulation materials must meet test standards under SOLAS. IMO-grounded

Thermal insulation fitted to refrigerated or temperature-controlled cargo spaces to maintain the required conditions.

The covering of hot surfaces such as exhaust pipes with insulation to reduce heat loss and, importantly, to prevent the ignition of oil, a fire-safety requirement under SOLAS. IMO-grounded

Insulation applied to bulkheads and decks for thermal, acoustic, or fire-protection purposes.

The insulated space surrounding a gas-carrier cargo tank that limits heat ingress and keeps the cargo at low temperature.

The standards a ship must meet for its stability in the undamaged condition, covering the righting-arm curve, metacentric height, and weather effects, set out in the International Code on Intact Stability. IMO-grounded

A proprietary seawater-intake or strainer system.

A tank that forms part of the ship's hull structure, its boundaries being the hull plating, as distinct from an independent tank. IMO-grounded

Tanks formed by the hull structure itself rather than fitted separately, common for liquid cargoes and ballast.

A bridge arrangement integrating navigation, communication, and control equipment into coordinated workstations, subject to performance standards and approval. IMO-grounded

A power arrangement in which all power, for propulsion and ship services, is generated electrically and distributed from a common system to electric propulsion motors.

A system that brings together the monitoring of many machinery and ship functions into a single coordinated display and alarm arrangement.

A propulsion unit supplied as a complete, integrated package combining the prime mover, drive, and propulsor.

A system in which several functions or sub-systems are combined and coordinated to work together.

The space between the primary and secondary barriers of a gas-carrier containment system, monitored for leakage of cargo. IMO-grounded

A heat exchanger that cools gas between the stages of a multi-stage compressor, improving efficiency.

Describing a structural member fitted in short lengths between other continuous members, as opposed to a continuous one.

An instrument that detects the boundary between two liquids, such as oil and water, used in cargo and separation operations.

A reusable container of moderate size for transporting liquids and granular substances in bulk, between drums and tanks in capacity.

The lengths of shafting between the engine or gearbox and the propeller (tail) shaft, supported by intermediate bearings.

A weld made in short lengths with gaps between, used where a continuous weld is not needed, saving weld metal and distortion.

The carriage of goods by more than one mode of transport (sea, road, rail) using the same loading unit, such as a container, without handling the goods themselves.

A proprietary or project designation relating to intermodal shipping.

An engine in which fuel is burned inside the working cylinders, such as the diesel and petrol engines, the main type of marine engine.

A gas-carrier tank type in which the insulation and a barrier are arranged on the inside of the supporting hull structure. IMO-grounded

The soundness of the ship's internal watertight boundaries, such as bulkheads, decks, and their closures, which limit flooding after damage. IMO-grounded

The body bringing together the major classification societies to develop common standards (unified requirements) and to support the technical work of the IMO. IMO-grounded

The IMO code, mandatory under SOLAS and MARPOL, setting the construction and equipment standards for ships carrying dangerous and noxious liquid chemicals in bulk. IMO-grounded

An international trade association representing shipowners and operators on technical, legal, and policy matters.

The IMO code, mandatory under SOLAS and the Load Line Convention, that sets the intact-stability criteria for ships and craft. IMO-grounded

SOLAS, the principal IMO treaty on the safety of merchant ships, covering construction, fire protection, life-saving, radio, navigation, and management. IMO-grounded

The IMO treaty that sets the minimum freeboards and related requirements limiting how deeply ships may be loaded, marked by the load line. IMO-grounded

The IMO code, mandatory under SOLAS, setting the standards for the construction and equipment of ships carrying liquefied gases in bulk. IMO-grounded

The IMO code, mandatory under SOLAS, governing the safe carriage of grain in bulk, addressing the stability hazards of grain shifting. IMO-grounded

A professional body for marine surveyors, promoting standards and education in marine surveying.

The United Nations agency dealing with labour standards, responsible for instruments on seafarers' working and living conditions, notably the Maritime Labour Convention. IMO-grounded

An international association representing the offshore, marine, and underwater engineering industries, issuing guidance and standards.

The IMO code, mandatory under SOLAS, governing the safe carriage of dangerous goods in packaged form by sea, including their classification, packing, marking, and stowage. IMO-grounded

The United Nations specialised agency responsible for developing and maintaining the international regulatory framework for shipping safety, security, and environmental protection. IMO-grounded

The international service that broadcasts navigational and meteorological warnings and other safety information to ships by direct-printing telegraphy, part of the GMDSS. IMO-grounded

An international fund that provides compensation for oil-pollution damage from tankers when the shipowner's liability is insufficient, under the civil-liability regime. IMO-grounded

The IMO code, mandatory under SOLAS, requiring companies to operate a safety management system covering safe operation of ships and pollution prevention. IMO-grounded

The IMO code, mandatory under SOLAS, setting security requirements for ships and port facilities to detect and deter threats such as terrorism. IMO-grounded

An international association representing companies that supply ships with stores, provisions, and equipment.

An international employers' organisation for shipowners on labour and crewing matters, now associated with the International Chamber of Shipping.

A standardised coupling, required by SOLAS, that allows a ship's fire main to be connected to a shore or another ship's water supply in an emergency. IMO-grounded

An international association of model-testing institutions that develops and recommends standard procedures for predicting ship hydrodynamic performance.

The International Association of Independent Tanker Owners, representing independent tanker owners on industry matters.

Describing electrical equipment and circuits designed so that they cannot release enough energy to ignite a flammable atmosphere, suitable for use in hazardous areas. IMO-grounded

A nickel-iron alloy with a very low coefficient of thermal expansion, used for the membranes of certain LNG cargo containment systems.

A power-electronic device that converts direct current to alternating current, used in electric drives and power supplies.

A metallic element, the basis of steel and cast iron, the principal structural materials of ships.

A dense dry bulk cargo whose high stowage weight concentrates loads in the holds; its carriage is addressed by the IMSBC Code, and it is commonly carried in alternate holds in bulk carriers. IMO-grounded

A proprietary product or system designation.

A distribution system whose neutral is not connected to earth, so that a single earth fault does not cause a large fault current, improving continuity of supply.

The planned schedule of a ship's voyage, listing ports and times.

The standard method recommended by the International Towing Tank Conference for predicting a ship's full-scale powering performance from model-test results.

The set of standard testing and analysis procedures recommended by the International Towing Tank Conference for hydrodynamic model testing and prediction.