E

The connection of electrical equipment and the ship's structure to a common reference (the hull) to provide a safe path for fault currents and to control static electricity, an important safety measure especially in hazardous areas.

Electronic Chart Display and Information System, a navigation system that displays electronic charts integrated with position and other data; when type-approved and used with official charts it can meet the chart-carriage requirements of SOLAS chapter V. IMO-grounded

Accelerated corrosion at the cut or exposed edges of steel plates, where coatings are thinnest and most easily broken, a common starting point for structural corrosion.

The grinding of plate edges to round or smooth them before coating, improving coating adhesion and reducing edge corrosion.

The shaping and cleaning of the edges of plates or pipes before welding, such as bevelling, to achieve a sound joint with proper penetration.

A tanker designed to carry edible (vegetable and animal) oils and fats, with tanks and systems suited to these cargoes; their carriage in bulk is addressed under the IBC Code. IMO-grounded

Vegetable and animal oils carried in bulk as cargo, requiring heated, coated tanks and careful handling to preserve quality.

The complete and proper completion of port formalities and procedures so that a ship is free to sail.

The ratio of useful output to input for a machine or process, a measure of how effectively energy or effort is converted to the desired result.

A rudder design incorporating features such as a bulb or twisted profile to recover energy from the propeller slipstream and improve propulsive efficiency.

The Engine International Air Pollution Prevention documentation confirming that a marine diesel engine meets the nitrogen-oxide limits of MARPOL Annex VI, supporting the engine's certification. IMO-grounded

A device that uses a high-velocity jet of fluid to entrain and pump another fluid, with no moving parts, used for example to strip tanks or drain bilges.

Craft that fly just above a surface, supported by the cushion of higher-pressure air (ground effect) under their wings; the IMO has developed guidance for WIG craft operating over water. IMO-grounded

Buckling of a structural member that occurs while the material is still within its elastic range, so that it would recover its shape if the load were removed before collapse.

A change of shape under load that is fully recovered when the load is removed, the material returning to its original dimensions.

The stress beyond which a material begins to deform permanently; below it, deformation is elastic and recoverable.

The property of a material that allows it to return to its original shape after a deforming load is removed.

Buckling that occurs when part of the material has yielded, so the collapse involves both elastic and plastic behaviour, typical of stocky members.

Machines that convert electrical energy into mechanical rotation, used throughout the ship to drive pumps, fans, winches, and other equipment.

The interconnected system of generators, switchboards, cabling, and consumers that distributes electrical power throughout the ship.

A distribution system in which the neutral point is connected to earth (the hull), affecting how faults behave and are detected and cleared.

A propulsion unit housing an electric motor in a pod below the hull that drives the propeller directly and can rotate to provide steering, giving high efficiency and manoeuvrability.

Propulsion arrangements in which prime movers drive generators supplying electric motors that turn the propellers, allowing flexible machinery layout and efficient part-load operation.

A control system combining electrical signalling with pneumatic (compressed-air) actuation to operate valves and equipment.

Corrosion driven by electrochemical cells on a metal surface in the presence of an electrolyte such as seawater, the dominant corrosion mechanism for ships' steel.

A high-deposition welding process for vertical joints in thick plate, in which the weld pool is contained by shoes and shielded by gas, used in shipbuilding for vertical seams.

The removal of scale or oxide from metal by an electrolytic process in a suitable solution.

A type-approved navigation system that displays official electronic charts with integrated navigational information; its use can satisfy SOLAS chart-carriage requirements and it must meet IMO performance standards. IMO-grounded

An official vector chart database, issued by hydrographic offices, used in ECDIS; ENCs are the official charts that allow ECDIS to meet chart-carriage requirements under SOLAS. IMO-grounded

A welding process for thick vertical joints in which the heat is generated by the resistance of a molten slag pool, allowing very high deposition in a single pass.

Lifts for moving people or goods between decks; passenger-ship lifts and their machinery spaces are subject to safety and fire-protection requirements.

To board a ship.

A ladder rigged at the embarkation station to allow people to board survival craft or descend to the water, required as part of life-saving arrangements under SOLAS and the LSA Code. IMO-grounded

A device on a cable-laying vessel that can rapidly brake or stop the running cable in an emergency to prevent loss or damage.

A situation threatening the safety of the ship, persons aboard, or the environment, requiring immediate response under the ship's emergency procedures.

The electrical services that must remain powered in an emergency, such as steering, lighting, communications, and fire systems, supplied from the emergency source of power. IMO-grounded

Backup propulsion or steering arrangements that allow a ship to maintain limited control or movement if the main systems fail.

Stowage lockers holding equipment for emergency use, such as fire-fighting, rescue, or pollution-response gear, located for ready access.

A portable air supply that provides breathable air for a short time to allow a person to escape from a space filling with smoke or gas; required and regulated under SOLAS and the FSS Code. IMO-grounded

A float-free radio beacon that, when activated, transmits a distress signal with the ship's identity and position to search-and-rescue satellites; carriage is required under SOLAS as part of the GMDSS. IMO-grounded

The organised actions taken to deal with an emergency aboard, following the ship's contingency plans and the procedures required under the ISM Code. IMO-grounded

A vessel stationed near an offshore installation to stand by for rescue, recovery of persons from the water, and support in an emergency.

The essential services that must be kept available in an emergency, supported by the emergency source of power and the ship's emergency arrangements.

An independent power source, such as an emergency generator or battery, that automatically supplies essential safety services if the main power fails; required and located in accordance with SOLAS. IMO-grounded

The ship-specific procedure, required for certain ships under SOLAS, describing how the vessel can be taken in tow quickly in an emergency. IMO-grounded

Pre-rigged equipment, required on tankers under SOLAS, that allows a tow to be connected and the ship to be towed promptly if it loses power or control. IMO-grounded

A powerful tug kept on standby to assist ships in difficulty, for example to take a disabled or drifting vessel in tow before it grounds.

The release of substances into the air, such as exhaust gases from engines; air emissions from ships are regulated under MARPOL Annex VI. IMO-grounded

A stable mixture of two liquids that do not normally mix, such as oil dispersed in water, which can complicate the separation of oily mixtures.

Water-based paints in which the binder is dispersed as an emulsion, drying as the water evaporates.

A navigating bridge fully enclosed against the weather, with the conning positions inside, as on most modern ships.

A space with limited openings and ventilation that may have a dangerous atmosphere; entry requires testing and precautions under IMO guidance and SOLAS enclosed-space entry and drill requirements. IMO-grounded

A proprietary integrated rudder and propeller arrangement designed to improve propulsive efficiency.

A design concept for transporting and supplying energy by sea, for example a vessel arrangement for regasifying and delivering natural gas.

A mandatory measure under MARPOL Annex VI expressing the carbon-dioxide output of a new ship per unit of transport work; each applicable ship's attained EEDI must be calculated, verified, and not exceed the required value. IMO-grounded

A proprietary engine-monitoring and control unit.

The machine that converts fuel energy into mechanical power to propel the ship or drive generators and auxiliaries.

The allowance between an engine's continuous service power and its maximum rating, kept in reserve for heavy weather, hull fouling, and ageing.

The space containing the main propulsion machinery and associated equipment; as a high fire-risk space it is subject to extensive fire-protection and safety requirements under SOLAS. IMO-grounded

The layout of machinery, systems, and access within the engine room, planned for operation, maintenance, safety, and escape.

The supporting machinery in the engine room other than the main engine, such as pumps, compressors, purifiers, and generators.

A bulkhead bounding the engine room, contributing to subdivision and, where required, providing fire and watertight integrity. IMO-grounded

A protected position in or near the engine room from which fire and emergency systems can be operated and the machinery space monitored.

The system supplying air for combustion, cooling, and a safe working environment in the machinery space, arranged so it can be controlled and shut down in a fire. IMO-grounded

Tests of an engine's performance and operation, carried out at the works and during the ship's sea trials, to confirm it meets its specification.

A certificated officer of the engine department responsible for operating and maintaining the ship's machinery, qualified under the STCW Convention. IMO-grounded

Going into a space; entry into enclosed spaces requires atmosphere testing and precautions under IMO requirements because of the risk of a dangerous atmosphere. IMO-grounded

The control of conditions such as temperature, humidity, and air quality within spaces to suit people, equipment, or cargo.

The loads imposed on a ship or structure by the environment, such as waves, wind, current, and ice, which the design must withstand.

Tough, chemically resistant resins widely used as the binder in high-performance protective coatings for ballast tanks, holds, and other demanding areas.

A figure calculated from a ship's dimensions and form that determines the size and amount of its anchoring and mooring equipment under classification rules. IMO-grounded

The assembly of fabricated units, blocks, and components into the complete structure of the ship at the building berth.

The design of equipment, workplaces, and tasks to suit human capabilities, improving safety, comfort, and efficiency, increasingly applied to bridge and machinery-space design.

The wearing away of a surface by the mechanical action of moving fluid or particles, as distinct from chemical corrosion.

The combined attack on metal by erosion and corrosion acting together, in which flow removes protective films and accelerates corrosion, common in pipes and pump components.

Material loss caused by erosion, for example by fast or particle-laden flow against a surface.

A deviation of a measured or computed value from the true value, or a mistake in operation; controlling error is important in navigation and instrumentation.

A clearly marked and unobstructed means of escape from a space to a place of safety, the provision of which is required by SOLAS to allow rapid evacuation in an emergency. IMO-grounded

A vertical trunk with a ladder providing a protected means of escape from a lower space, such as a machinery space or hold, to an upper deck. IMO-grounded

A tug or vessel accompanying a ship, for example a tanker in confined waters, ready to assist with steering or stopping in an emergency.

Equipment necessary for the safe operation and navigation of the ship, which must remain available, including under emergency conditions. IMO-grounded

The services necessary for propulsion, steering, and safety that must be maintained for the ship to operate safely, identified in the design of the power and machinery systems. IMO-grounded

Ethanol used as a fuel or fuel component, of interest as a lower-carbon alternative, with handling and flammability considerations.

The orderly movement of people away from danger to survival craft or a place of safety, supported by escape routes, marine evacuation systems, and drills under SOLAS. IMO-grounded

The change of a liquid into vapour at its surface, exploited in evaporators that produce fresh water from seawater, and a factor in cargo boil-off.

The inspection of the hull's structural members for corrosion, cracks, deformation, and wastage, carried out during surveys to verify continued strength and integrity. IMO-grounded

Corrosion that has reduced structural thickness beyond acceptable limits, requiring renewal of the affected steel, as assessed against survey criteria. IMO-grounded

The pollutants released in an engine's exhaust, such as nitrogen and sulphur oxides and particulates, which are limited under MARPOL Annex VI. IMO-grounded

A boiler that recovers heat from the main engine's exhaust gas to raise steam, improving overall fuel efficiency.

Equipment, commonly a scrubber, that removes sulphur oxides and other pollutants from exhaust gas, allowing a ship to meet the sulphur limits of MARPOL Annex VI while burning higher-sulphur fuel. IMO-grounded

A technique that routes part of the exhaust gas back into the engine's intake to lower combustion temperatures and reduce nitrogen-oxide formation, helping meet MARPOL Annex VI NOx limits. IMO-grounded

A turbocharger driven by the engine's exhaust gas, using that energy to compress the intake air and increase the engine's power and efficiency.

The hot gaseous products of combustion leaving an engine or boiler, carrying both recoverable heat and regulated pollutants.

The valve that opens to release the burnt gases from an engine cylinder into the exhaust system.

A raised trunk on a tank that provides space for the cargo to expand and contract with temperature while keeping the main tank full, reducing free-surface effects.

A valve that opens to relieve the pressure of an internal explosion, such as in a crankcase, protecting the enclosure from bursting.

Describing electrical equipment built so that it cannot ignite a surrounding explosive atmosphere, required for use in hazardous areas such as tanker cargo zones. IMO-grounded

A mixture of flammable gas or vapour with air in proportions that will explode if ignited, the prevention of which underlies inerting and gas-control measures on tankers. IMO-grounded

Corrosion affecting a large area of structure, indicating widespread deterioration that must be assessed and repaired. IMO-grounded

Hydraulic cylinders mounted externally, for example to operate steering gear, hatch covers, or ramps.

The greatest breadth of the ship measured to the outermost points, including any projections, as distinct from the moulded breadth.

The depth of the ship measured to the outermost points, including the keel and any structure, as distinct from the moulded depth.

The greatest draught measured to the lowest point of the ship, including any projections below the keel line.