S

The international hydrographic standard for the exchange of digital chart data, the basis for electronic navigational charts used in ECDIS. IMO-grounded

A block of a more reactive metal, such as zinc or aluminium, fitted to steel so that it corrodes in place of the steel, protecting it by cathodic action.

A corrosion-protection method using sacrificial anodes that corrode preferentially to protect the hull and tank steel.

A system on anchor-handling vessels designed to make the handling of rig anchors and heavy gear safer for the crew.

A SOLAS concept for large passenger ships requiring that, after a casualty within defined limits, the ship can return to port under its own power with essential systems available. IMO-grounded

The speed at which a vessel can take proper and effective action to avoid collision and stop within an appropriate distance, as required by the collision regulations (COLREGs). IMO-grounded

The maximum load that lifting gear or a fitting is certified to handle safely in normal use.

Procedures and precautions followed to carry out shipboard work without injury or accident, set out in codes of safe working practice.

The maximum pressure at which equipment or a system may be operated safely.

A bursting disc or similar device that fails at a set pressure to relieve a system and prevent dangerous overpressure.

A system provided to protect the ship, persons, or environment, such as fire detection, alarms, shutdowns, and protective devices.

A valve that opens automatically to relieve pressure above a set limit, protecting boilers, pressure vessels, and systems; required and certified for boilers.

A bridge or control position from which safety systems can be monitored and operated.

A controlled area around an offshore installation within which navigation is restricted for safety.

The bending of a ship's hull so that the middle is lower than the ends, for example when a wave trough is amidships; the opposite of hogging.

Runs or downward flow of a paint film that is applied too thickly, leaving an uneven, drooping surface.

A canal linking inland waters to the sea, whose dimensions define a class of vessels able to use it.

The concentration of dissolved salts in water, affecting its density and corrosiveness and relevant to ballast and boiler water.

An instrument that measures the salinity of water, used for example to check the purity of fresh water produced aboard.

The rescue of a ship or cargo from peril at sea, and the reward to which the salvors are entitled for a successful service.

An organisation concerned with the survey and assessment of marine casualties and salvage on behalf of insurers and others.

An operation to save a ship, its cargo, or other property from danger at sea, or to limit environmental damage.

A powerful tug equipped for salvage work, able to take a casualty in tow and provide fire-fighting and pumping assistance.

A strong vertical post supporting cargo-handling derricks.

A heavy-duty trailer used for moving very heavy loads in ports and aboard ro-ro ships.

Surface preparation by blasting with sand; now largely replaced by other abrasives because of the health hazard of silica dust.

A structural system in which a polymer core is bonded between two steel plates, used to strengthen or renew decks and structures.

Discharges of grey and black water from accommodation, the disposal of sewage being regulated under MARPOL Annex IV. IMO-grounded

A pump supplying water for sanitary services aboard ship.

Steam at the temperature of boiling for its pressure, in equilibrium with water, as distinct from superheated steam.

In diving, the state in which a diver's tissues are fully saturated with breathing gas at depth, allowing long stays; also, the point at which a substance can hold no more of another.

Hard mineral deposits formed on heating surfaces from impurities in water; also mill scale on steel, or the proportion of a model to full size.

A curved cut-out in a structural member, for example to clear a weld or allow drainage.

The maximum draught for which the ship's structure (scantlings) is designed, which may exceed the assigned load-line draught. IMO-grounded

The dimensions of a ship's structural members, such as plate thicknesses and stiffener sizes, determined by classification rules. IMO-grounded

The system that supplies scavenge air to a two-stroke engine to clear exhaust gas from the cylinders and provide fresh air for combustion.

A fire in the scavenge air space of a two-stroke engine, caused by the ignition of accumulated oil and combustion residues.

The clearing of burnt gases from an engine cylinder and their replacement with fresh air, essential in the two-stroke cycle.

The arrangements (such as loop, cross, and uniflow scavenging) by which a two-stroke engine clears exhaust and admits fresh air.

The location of an incident, such as the scene of a search-and-rescue operation.

A high-lift rudder with a flared, fishtail trailing edge that gives strong steering forces and good low-speed manoeuvring.

A flow-improving duct fitted ahead of the propeller to even the inflow and improve propulsive efficiency.

A platform raised and lowered by a scissor mechanism, used to move cargo or vehicles between decks.

A proprietary system or designation.

A cooling-water arrangement that uses the ship's forward motion to force seawater through the system via a scoop, reducing pump use at speed.

A proprietary design concept.

A ring on a piston or rod that scrapes excess oil from the surface, controlling lubrication and oil consumption.

A plate fitted as a screen or barrier, for example to shield a navigation light so it shows over the correct arc.

The opening in the stern structure within which the propeller turns.

A valve that can be screwed shut and also acts as a non-return valve, allowing flow one way and being positively closable.

The sideways force a turning propeller exerts on the stern (paddlewheel effect), which affects low-speed manoeuvring.

A valve opened and closed by screwing its disc up and down onto a seat.

A positive-displacement pump using intermeshing screws to move fluid smoothly, suited to viscous liquids such as fuel and lube oil.

Equipment that cleans exhaust gas by passing it through water or a chemical solution to remove sulphur oxides and particulates, enabling compliance with MARPOL Annex VI sulphur limits. IMO-grounded

A valve used to remove the surface scum from a boiler's water as part of water management.

Openings and pipes that drain water from decks overboard or to a collecting system.

A small opening with a cover, such as a sidescuttle (porthole) or an access scuttle; also to deliberately sink a ship.

A proprietary sharp, deep bow form designed to slice through waves and reduce slamming on fast support vessels.

A recess in the hull bottom or side, fitted with a grating, through which seawater is drawn into the ship's systems.

Part of the phrase relating to harmful substances carried by sea in packaged form, regulated under MARPOL Annex III and the IMDG Code. IMO-grounded

An offshore berth structure standing apart from the shore at which tankers moor to load or discharge.

A power allowance added in design to cover the increase in resistance from weather and hull fouling, so the ship can keep its service speed in service.

Systems that measure and report the sea conditions a ship is experiencing, supporting safe operation and route decisions.

The intake of seawater into the ship's systems through a sea chest and suction valve.

The planned schedule of trials carried out at sea to verify a new ship's speed, manoeuvring, machinery, and systems before delivery.

A proprietary fine, arrow-shaped bow form intended to reduce wave-making resistance.

A vessel intended for and capable of navigation at sea, as distinct from inland or harbour craft.

A person employed or engaged in any capacity aboard a ship; seafarers' rights and conditions are protected under the Maritime Labour Convention. IMO-grounded

The behaviour and performance of a ship in a seaway, including its motions, accelerations, and ability to maintain speed and operate safely.

A channel that retains a hatch-cover or other seal in position (OCR-truncated term for a seal retaining channel).

A longitudinal joint between plates; in welding and structure, the line along which plates are joined edge to edge.

A member of a ship's crew, particularly of the deck department.

A boat used for search-and-rescue operations to locate and recover persons in distress.

A device that, when triggered by a radar, transmits a signal showing on the radar screen to mark the position of survival craft, part of the GMDSS. IMO-grounded

A systematic path flown or sailed to search an area for a person or object in distress, following standard SAR patterns. IMO-grounded

The speed at which a search unit travels while conducting a systematic search, chosen for effective detection.

A surface against which a valve disc closes to make a seal; also a supporting foundation for equipment.

The fitness of a ship in all respects, including structure, equipment, manning, and stowage, to undertake its intended voyage safely.

Describing a ship that is fit in all respects to encounter the ordinary perils of the intended voyage.

An engineer officer ranking below the first assistant, equivalent to a third engineer in some structures.

A deck officer ranking below the chief mate, traditionally responsible for navigation and charts.

In a gas carrier, a liquid-tight barrier behind the primary one that temporarily contains any leaked cargo and protects the hull from the cold, required under the IGC Code. IMO-grounded

An intermediate fluid that carries heat between the refrigerant and the space or process being cooled in an indirect refrigeration system.

Equipment that need not run continuously but must be available for the ship's safe operation, identified in the design of the electrical system. IMO-grounded

A fluid such as brine or glycol circulated to provide cooling without the primary refrigerant entering the cooled space.

A board or panel used in laying off or assembling hull sections.

A geometric property of a structural cross-section relating bending moment to the resulting stress; the hull-girder section modulus governs longitudinal strength.

A large proprietary cargo unit used to carry forest products in a standardised, stackable box handled by cassette systems.

Any suspicious act or circumstance threatening the security of a ship or port facility, addressed under the ISPS Code. IMO-grounded

One of three graduated levels of security (normal, heightened, exceptional) set under the ISPS Code, determining the measures a ship or port facility must apply. IMO-grounded

Lighting provided to support security by illuminating access points and the ship's surroundings, part of security measures under the ISPS Code. IMO-grounded

The settled solids and residues that accumulate in tanks, such as ballast-tank sediment and oil sludge, the management of which is addressed under MARPOL. IMO-grounded

Ballast water carried in tanks entirely separate from the cargo and fuel systems, so it never contacts oil; required on tankers under MARPOL Annex I. IMO-grounded

Dedicated ballast tanks completely separate from the cargo oil and fuel systems, required on oil tankers to prevent oil pollution from ballast under MARPOL Annex I. IMO-grounded

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

A fishing net that hangs vertically and is drawn together to enclose fish; the basis of seine fishing.

A fishing vessel that catches fish using a seine net, such as a purse seiner.

A fishing vessel able to operate both as a seiner and as a trawler.

A vessel that explores the sub-seabed by generating sound pulses and recording the reflections with towed streamers, used in oil and gas exploration.

An exhaust after-treatment system that injects a reagent and passes the gas over a catalyst to convert nitrogen oxides into nitrogen and water, used to meet the NOx limits of MARPOL Annex VI. IMO-grounded

An anti-fouling coating whose surface gradually wears away in a controlled manner to expose fresh biocide, maintaining a smooth, fouling-resistant surface; biocides are controlled under the AFS Convention. IMO-grounded

Model tests in which a powered model is run to determine the interaction between hull and propeller and to predict the full-scale power required.

A liferaft designed to turn itself the right way up if it inflates or capsizes inverted, required to meet standards under the LSA Code. IMO-grounded

An independent gas-carrier cargo tank of prismatic shape that carries its own loads, a containment type under the IGC Code. IMO-grounded

A cargo tank that supports itself and its contents independently of the hull, used on gas carriers under the IGC Code. IMO-grounded

Describing a bulk carrier whose hold shape causes cargo to settle evenly and fill the space without manual trimming.

Onboard conveyor and boom systems that allow a bulk carrier to discharge its cargo without shore equipment.

A proprietary stair or evacuation system.

Welding in which the wire feed is automatic but the welder guides the torch by hand, as in gas-shielded processes.

A rudder with part of its area forward of the turning axis, reducing the torque needed to turn it compared with an unbalanced rudder.

A gas-carrier tank that is largely supported by the hull through insulation but retains some self-supporting character, a containment type under the IGC Code. IMO-grounded

A rudder partly supported by a horn with a single pintle bearing, combining features of spade and horn-mounted rudders.

Vessels or units that can be partly submerged by ballasting, used as heavy-lift float-on/float-off carriers or as stable offshore platforms.

A device that detects and measures a physical quantity and converts it into a signal for monitoring or control.

To divide or keep apart; in cargo terms, to keep cargoes apart to avoid contamination or reaction.

A tank kept separate from others so its contents do not mix, used for example to segregate cargo grades or ballast.

The dividing of a mixture into its components, such as the separation of oil and water in a separator.

Equipment that separates the components of a mixture, such as a centrifugal purifier separating water and solids from oil.

A ballast-water exchange method in which a tank is emptied and then refilled with open-ocean water, to meet the D-1 standard of the BWM Convention. IMO-grounded

A category of marine casualty involving significant damage or consequences, subject to investigation under the Casualty Investigation Code. IMO-grounded

Vessels that provide services rather than carry cargo, such as tugs, supply vessels, and buoy tenders.

Spaces used for galleys, pantries, stores, workshops, and similar service functions, with fire-protection treatment under SOLAS. IMO-grounded

A tank holding treated fuel or oil ready for immediate use by the machinery, kept topped up from the settling tanks.

A tank in which fuel or oil is allowed to stand so that water and solids settle out before the oil is drawn off for treatment.

Waste from toilets, medical spaces, and certain other sources, the discharge of which from ships is regulated under MARPOL Annex IV. IMO-grounded

The treatment of sewage aboard to a standard permitting discharge, and the wider handling of ship-generated wastes, under MARPOL Annexes IV and V. IMO-grounded

A U-shaped metal link closed by a pin, used to connect chains, ropes, and fittings; also a length of anchor cable.

A rotating member that transmits power, such as the propeller shaft connecting the engine to the propeller.

The correct positioning of the propeller shafting and its bearings so that loads are properly shared and excessive stress and vibration are avoided.

A method of checking shaft alignment by sighting along the shaft line to verify that the bearings are correctly positioned.

An alternator driven from the main propulsion shaft to generate electrical power while the ship is underway, saving auxiliary fuel.

The bearings that support the propeller shafting along its length, allowing it to rotate with minimal friction.

The connection joining lengths of shafting or the engine to the shaft, transmitting torque.

A device that earths the propeller shaft to the hull, controlling shaft voltage and preventing corrosion and bearing damage from stray currents.

A protected passage through which the propeller shaft runs from the machinery space to the stern, allowing access and inspection.

The line of shafts connecting the main engine or gearbox to the propeller, including intermediate and tail shafts.

Natural gas extracted from shale rock formations, a source of natural-gas cargoes and fuel.

Deck fittings on an anchor-handling vessel that grip and hold chain or wire during anchor handling and towing.

The internal force acting across a section of a beam or hull girder tending to slide one part past the other; its distribution along the hull is fundamental to structural strength.

Stress acting parallel to a surface, tending to cause adjacent layers to slide over one another.

A protective covering, for example over a cable or a propeller-shaft liner.

A sloping plate fitted in a corrugated bulkhead or hold corner that directs cargo away and prevents it lodging, aiding discharge and reducing loads.

The longitudinal curvature of the deck line, rising toward the bow and stern, which adds reserve buoyancy at the ends.

The uppermost strake of side shell plating, at the deck edge, a highly stressed strength member of the hull girder.

A heavy-lift crane on a barge or pontoon with a fixed lifting frame, used for very heavy lifts in harbours.

A door in the ship's side or stern giving access for cargo, vehicles, or stores, which must maintain watertight integrity; subject to SOLAS requirements. IMO-grounded

A drawing showing the layout, thickness, and seams of the shell plating laid out flat, used in construction and survey.

The plating forming the outer skin of the hull, providing watertight integrity and contributing to strength.

A heat exchanger in which one fluid flows through a bundle of tubes and another around them within a shell, a common type of cooler and condenser.

A deck enclosing a space above the main hull, historically associated with particular tonnage arrangements.

A proprietary monitoring or logging system.

Manual arc welding using a flux-coated electrode that provides both filler metal and a shielding gas and slag, a versatile process for steel.

A gas supplied to protect the molten weld pool from the atmosphere in gas-shielded welding processes.

Cargoes liable to move within the hold under the ship's motions, endangering stability; their stowage and securing are addressed in the cargo codes. IMO-grounded

A thin spacer used to take up a gap or adjust the alignment or fit of components.

A vessel used for navigation at sea; the term has specific meanings under the various IMO conventions that define their application. IMO-grounded

A mechanical lift used to raise and lower a vessel between water levels or out of the water, an alternative to a lock or dry dock.

A permanent unique number assigned to a ship under the IMO ship identification number scheme, required to be marked on the ship and used throughout its life regardless of changes of name or flag. IMO-grounded

Test facilities in which scale models are run to study ship resistance, propulsion, seakeeping, and manoeuvring.

The six motions of a ship in a seaway (surge, sway, heave, roll, pitch, yaw), which affect comfort, cargo, structure, and operability.

The person aboard, accountable to the master, responsible under the ISPS Code for the ship's security, including the implementation and maintenance of the ship security plan. IMO-grounded

A manual, required under SOLAS for certain ships, describing the means of safe access to the cargo and ballast spaces for inspection and maintenance. IMO-grounded

The various categories of ship classified by the cargo they carry or the function they perform, such as tankers, bulk carriers, container ships, and passenger ships.

The transfer of cargo, typically oil or gas, between two ships moored alongside each other at sea or at anchor, carried out under controlled procedures and, for oil, addressed by MARPOL. IMO-grounded

The burning of shipboard wastes in an incinerator aboard, which is regulated to control emissions and the types of waste burned under MARPOL Annexes V and VI. IMO-grounded

Equipment for burning shipboard-generated waste aboard; approved incinerators must meet standards under MARPOL Annex VI. IMO-grounded

A plan, required for certain ships under MARPOL, setting out the action to be taken in the event of a pollution incident involving oil or noxious liquid substances. IMO-grounded

A plan, required under MARPOL Annex I, giving the master and crew the procedures to follow to respond to an oil-pollution incident. IMO-grounded

A manual providing technical information and operating instructions for the ship's equipment and systems.

Tests of machinery, systems, and equipment carried out aboard to verify their performance and compliance.

An intermediary who arranges the chartering, sale, or purchase of ships on behalf of clients.

A consignment of goods carried, or the act of sending goods by ship.

The person or company that owns a ship, with ultimate responsibility for it, though operation may be delegated to a manager or operator.

A facility where ships are built, repaired, or converted.

A thin protective coating applied to steel plates and sections early in fabrication to protect them during building until the full coating is applied.

Electrical power taken from a shore connection while in port, allowing the ship's generators to be shut down; also called cold ironing.

A sound signal of about one second's duration, used in the manoeuvring and warning signals of the collision regulations (COLREGs). IMO-grounded

An unintended low-resistance connection in an electrical circuit that allows excessive current to flow, guarded against by protective devices.

An international voyage defined under SOLAS by limits on its length and distance from refuge, for which some passenger-ship requirements are modified. IMO-grounded

Equipment that breaks up waste into small pieces to reduce its volume for storage and disposal under MARPOL Annex V. IMO-grounded

A propeller surrounded by a duct or nozzle that improves thrust at low speed or protects the blades; see Kort nozzle.

A tanker that carries oil from an offshore production or storage facility to shore, often fitted with dynamic positioning and bow-loading equipment.

Plating forming part of the ship's side shell.

A bow door that opens by sliding to one side to give vehicle access on a ro-ro ship.

A container-securing arrangement that supports and restrains stacks from the sides.

Cargo-handling systems that load and discharge through doors in the ship's side rather than over the top, used for pallets and unitised cargo.

Ships fitted with side ports and internal handling systems to load and discharge cargo through the ship's side.

The sideways force a turning propeller exerts on the stern, affecting low-speed steering; see screw effect.

An air-cushion craft with rigid side walls that contain the cushion at the sides, with flexible seals only at bow and stern.

The red (port) and green (starboard) navigation lights showing over the forward arcs, prescribed by the collision regulations (COLREGs). IMO-grounded

Supports bracing cargo or structure against the ship's side to prevent movement.

A proprietary podded electric propulsion unit providing combined propulsion and steering.

Lights used to convey messages or signals between ships or between ship and shore.

A single filter unit, as opposed to a duplex arrangement, which must be taken out of service to be cleaned.

A simplified version of the voyage data recorder that stores a reduced set of data, accepted for certain existing ships under SOLAS to assist casualty investigation. IMO-grounded

A drill method that exercises the release and recovery of a free-fall lifeboat without an actual free-fall drop, to train the crew safely, as recommended by IMO. IMO-grounded

An offshore mooring in which a tanker connects to a buoy held by a single anchored leg, allowing it to weathervane while loading or discharging.

A bottom structure without an inner bottom, the shell forming the only bottom boundary, used on some smaller ships.

A deck fitting with a single opening for leading a mooring or towing line.

An offshore mooring buoy or structure to which a tanker secures at a single point and weathervanes around it while connected to a pipeline for loading or discharging.

A hatch cover whose panels are opened together by a single pulling action.

A joint welded from one side only, as opposed to a double-welded joint.

A means of moving liquid over a barrier by atmospheric pressure through an inverted U of pipe.

A ship built to the same design as another, sharing the same hull form and arrangements.

A fixed fin or extension of the hull at the stern, ahead of or supporting the rudder, that improves directional stability and may support the propeller shaft.

A small open boat.

Devices that remove floating oil from the water surface during spill recovery.

The frictional resistance arising from the flow of water over the hull surface, a major component of a ship's total resistance.

The flexible curtain around an air-cushion vehicle that contains the cushion of air on which it rides.

A glazed opening in a deck or deckhouse top that admits light and air to the space below.

A partly filled tank in which the liquid is free to move, creating a free-surface effect that reduces the ship's stability. IMO-grounded

Particles of slag trapped in a weld, a defect that can weaken the joint.

The rotation of a crane or other equipment about a vertical axis.

A ro-ro ramp that can be swung (slewed) to one side to align with a shore connection at an angle.

A proprietary hull form using submerged pods and struts to give good seakeeping and low resistance.

Doors that open and close by sliding, used for example as watertight doors. IMO-grounded

A loop or arrangement of rope, wire, or chain used to attach a load to a lifting hook.

To let go a mooring or tow quickly; also the difference between the theoretical and actual advance of a propeller per revolution.

An inclined surface on which ships are built or hauled out and launched.

A chute used to discharge certain wastes from a ship, under the conditions allowed by MARPOL. IMO-grounded

A tank on a tanker used to collect oily residues, tank washings, and slops, allowing the oil to separate before controlled disposal under MARPOL Annex I. IMO-grounded

The tanks in which oily washings and residues are collected and settled aboard a tanker before disposal in accordance with MARPOL Annex I. IMO-grounded

The treatment of oily slop water aboard a tanker so that the separated water can be discharged within the limits set by MARPOL Annex I. IMO-grounded

The deliberate operation of a ship at reduced speed to lower fuel consumption and emissions.

The thick residue of oil, water, and solids that accumulates from fuel and oil treatment and in tanks, the disposal of which is regulated under MARPOL. IMO-grounded

The removal of accumulated sludge, which must be delivered to reception facilities or incinerated rather than discharged to sea, under MARPOL Annex I. IMO-grounded

Oily residue separated from fuel and lubricating oil during purification, retained aboard for proper disposal under MARPOL Annex I. IMO-grounded

A tank for storing oily sludge from machinery-space operations until it can be disposed of ashore or by incineration, required under MARPOL Annex I. IMO-grounded

A gate valve used to open and close a passage for liquid; also a valve in a bulkhead allowing controlled flooding between compartments.

A twin-hull craft with most of its buoyancy in submerged lower hulls and slender struts piercing the surface, giving excellent seakeeping.

A strong deck fitting provided for emergency towing connections. IMO-grounded

A mixture of smoke and fog, or polluted haze, associated with air pollution.

The visible airborne products of combustion, an indicator of fire and a hazard to escape and breathing.

The Shipboard Marine Pollution Emergency Plan, required for certain ships under MARPOL, covering response to oil and noxious-liquid-substance pollution incidents. IMO-grounded

A sudden change of shape in which a curved or loaded structure jumps from one stable form to another, a particular instability mode.

A professional society for naval architects and marine engineers, promoting knowledge and standards in the field.

A protective coating that remains soft and is intended to be inspected and maintained, used in some tanks, as distinct from a hard coating.

The International Convention for the Safety of Life at Sea, the principal IMO treaty governing the safety of merchant ships in construction, equipment, and operation. IMO-grounded

The SOLAS damage-stability standard introduced in 1990 for ro-ro passenger ships, against which their survivability after damage is assessed. IMO-grounded

Dry cargo carried loose in bulk, such as ore, coal, and grain, whose safe carriage is governed by the IMSBC Code. IMO-grounded

A propeller in which the blades are cast integrally with the boss, as opposed to one with separately attached or controllable-pitch blades.

A coating containing little or no solvent, reducing emissions and allowing thick films, used in tanks and demanding areas.

Liquids used to dissolve and thin the binder in paints and to clean surfaces, which evaporate as the paint dries.

A system that uses sound to detect and locate underwater objects and to measure depth, used in survey, fishing, and navigation.

Devices that blow steam or air to clean soot from boiler and economiser heating surfaces to maintain heat transfer.

Advanced, high-performance coatings such as two-pack epoxies and polyurethanes, as distinct from conventional paints.

A pipe through which the level of liquid in a tank is measured by lowering a sounding rod or tape.

The compartments and areas of a ship, classified for various purposes such as fire protection, cargo, and accommodation.

A rudder supported only at its top by the rudder stock, with no lower bearing, hanging like a spade.

A floating offshore platform consisting of a large deep-draught vertical cylinder moored to the seabed, giving good stability in deep water.

A device fitted to an exhaust or funnel that traps or extinguishes sparks to prevent them igniting flammable material.

An engine in which the fuel-air mixture is ignited by an electric spark, as in petrol and some gas engines.

Small globules of metal thrown out during welding that adhere to the surrounding surface.

Enclosed vehicle spaces accessible by drive-in vehicles into and from which passengers may have access, subject to stringent fire-safety requirements under SOLAS. IMO-grounded

Openings through the hull for sea connections, shafts, and other services, which require careful design to maintain watertight integrity.

A mechanically self-propelled ship that carries more than a defined number of special personnel aboard for its function, such as research or training ships, governed by the IMO SPS Code. IMO-grounded

The most severe environmental conditions (wind, wave, current) within which a craft or operation is designed to function safely.

The rate of a ship's progress, usually measured in knots through the water or over the ground.

Instruments that measure and record a ship's speed through the water or over the ground.

Trials run to measure a ship's speed at various engine powers, usually over a measured course, to verify its performance.

Equipment kept aboard to contain and clean up spills of oil or chemicals, such as absorbents, booms, and tools, required under pollution-prevention plans. IMO-grounded

A rotating or sliding rod, such as the stem of a valve.

A curved internal ramp on a car carrier or ro-ro ship allowing vehicles to drive between decks in a spiral.

Constructed so as to be protected against splashing water from any direction.

Protective clothing that guards the wearer against splashes of chemicals, part of the protective equipment on chemical tankers. IMO-grounded

A proprietary or OCR-uncertain term.

A mooring winch whose drum is divided into a tension part and a storage part, keeping the working turns separate from the stored line.

A mooring-winch drum divided so that the working line is held on one part and the spare line stored on another.

A joint divided or made in parts.

Projections from the hull that add buoyancy or stability, such as the side floats of a multi-hull or the sponsons that increase a vessel's beam.

A mooring arrangement in which several lines or anchors are led out in different directions to hold a floating unit on station and resist environmental forces.

A lifting frame that grips a container at its corner castings for handling by crane; also a beam that holds lifting slings apart.

The area a given quantity of paint will cover at the specified film thickness.

Mooring lines led fore-and-aft at an angle to prevent the ship from moving ahead or astern along the berth.

A sandwich-plate-system overlay bonded onto a deck to strengthen or renew it without full steel replacement.

The bodily sinkage and change of trim a ship experiences when moving in shallow water, reducing under-keel clearance.

The ability of a ship to return to the upright after being heeled by an external force, assessed against intact and damage stability criteria. IMO-grounded

The information on a ship's stability characteristics, such as hydrostatics and cross curves, used to assess loading conditions.

The approved stability information supplied to the ship, including the stability manual and data, required under SOLAS and the Load Line Convention. IMO-grounded

An approved onboard computer that calculates the ship's stability and, often, strength for a given loading, required for certain ships under SOLAS. IMO-grounded

A hatch cover panel that is stacked upon another to open the hatch.

Fixed stairs providing access between decks, forming part of the means of escape and subject to fire-protection requirements under SOLAS. IMO-grounded

An upright post supporting a rail, deck, or guardrail.

A test in which a structural division is exposed to a defined temperature-time fire to determine its fire resistance, used to classify divisions under SOLAS and the FTP Code. IMO-grounded

The representative loading conditions for which a ship's stability and strength are calculated and presented in its approved documentation. IMO-grounded

Vessels stationed near offshore installations to provide rescue and recovery in an emergency; see emergency response and rescue vessel.

A tug kept ready to assist a ship or installation, for example during berthing or offshore operations.

The right-hand side of a ship when facing forward.

A load that is steady and unchanging with time, as opposed to a dynamic load.

The certificates a ship must carry to show compliance with international conventions, such as the safety, load line, and pollution-prevention certificates, issued under SOLAS, the Load Line Convention, and MARPOL. IMO-grounded

The surveys required by international conventions to verify a ship's compliance and issue or endorse its statutory certificates. IMO-grounded

Water in its gaseous state, generated in boilers for propulsion, cargo heating, and auxiliary services.

A heat exchanger that condenses exhaust steam back to water by passing it over tubes carrying cooling seawater, recovering the feed water.

A device that automatically drains condensate from a steam system while preventing the escape of steam.

An engine in which steam expands through blades to drive a rotor, used for propulsion and power generation, notably on some LNG carriers.

The iron-carbon alloy that is the principal structural material of ships, supplied in grades and strengths specified by classification rules. IMO-grounded

The shop where steel plates are cleaned by blasting and given a shop primer before fabrication.

Steel cargoes such as plates, coils, bars, and pipes, which are heavy and require careful stowage and securing.

Direct metal contact between a hatch cover and its coaming or between structures, which may be a design feature to take load or a sign of seal failure.

A proprietary steel pad used in cargo or equipment securing.

The machinery that moves the rudder in response to the helm; its capability, redundancy, and testing are governed by SOLAS and class rules. IMO-grounded

The space housing the steering gear, which must be readily accessible and, on many ships, separated from machinery spaces, under SOLAS. IMO-grounded

The system that transmits the steering command from the bridge to the steering gear and controls the rudder movement.

The motor and pump unit that provides the power to operate the steering gear; SOLAS requires sufficient units and redundancy. IMO-grounded

A movable Kort nozzle that both increases thrust and steers the vessel by directing the propeller race.

The complete arrangement of controls, power units, and gear by which the ship is steered.

The foremost structural member of the bow, to which the side shell plating is connected.

The after end of a ship.

An arrangement on a tanker for loading or discharging cargo through a connection at the stern.

The heavy structure at the stern that supports the rudder and, in single-screw ships, surrounds the propeller aperture.

The part of the stern frame through which the propeller shaft passes, supporting the stern tube.

Mooring lines led aft from the stern to hold it to the berth.

A ro-ro ramp at the stern quarter, set at an angle, allowing vehicles to drive on and off at a berth.

A combined ramp and door at the stern of a ro-ro ship through which vehicles are loaded, which must maintain watertight integrity; subject to SOLAS requirements. IMO-grounded

A white navigation light shown at the stern over the after arc, prescribed by the collision regulations (COLREGs). IMO-grounded

The bearings within the stern tube that support the propeller shaft where it passes through the hull.

The system that supplies and contains oil lubricating the stern-tube bearings and seals, arranged to prevent pollution from leakage. IMO-grounded

The seals at each end of the stern tube that retain the lubricant and exclude seawater around the propeller shaft.

A worker, or company, engaged in loading and discharging ships' cargo.

A secondary structural member attached to plating to increase its stiffness and strength, such as a frame, beam, or longitudinal.

The resistance of a structure to deformation under load.

An external-combustion engine driven by the cyclic heating and cooling of a working gas, used in some specialised and quiet applications.

A regional agreement setting enhanced damage-stability requirements for ro-ro passenger ships operating in north-west European waters, accounting for water on the vehicle deck. IMO-grounded

A device or arrangement used to absorb impact or vibration.

Valves used to start and stop the flow in a line, such as the main steam stop valve on a boiler.

A device that holds and secures a chain, rope, or moving part, such as a chain stopper or a cargo stopper.

An OCR-truncated term for stopping ability, the measure of how quickly a ship can be brought to rest, assessed in the crash-stop test under the IMO manoeuvring standards. IMO-grounded

A buoy that stores oil or serves as the connection point for offloading from an offshore facility to a tanker.

The placing and arrangement of cargo in the ship so as to make best use of space and to maintain safety, stability, and ease of discharge.

The volume occupied by a unit weight of a particular cargo, used to plan how much can be loaded in a given space.

Fittings used to hold and secure equipment or cargo in its stowed position.

A person who hides aboard a ship to travel without permission, the handling of whom is addressed by international guidance. IMO-grounded

Wheeled vehicles that straddle and lift containers to move and stack them in a terminal.

The deformation of a material under stress, expressed as the change in dimension relative to the original.

A device that removes coarse solids from a fluid to protect equipment downstream.

A continuous line (course) of shell or deck plating running fore and aft.

The running aground of a ship so that it is held fast on the seabed or shore.

Long towed cables carrying hydrophones, deployed behind a seismic survey ship to record reflected sound from the sub-seabed.

A bulkhead that contributes significantly to the structural strength of the hull, in addition to subdividing it.

The uppermost continuous deck that acts as the top flange of the hull girder and is a principal contributor to longitudinal strength.

The ability of a structure to carry its loads without failure by yielding, buckling, or fracture.

The internal force per unit area within a material resulting from applied loads.

A local increase in stress at a discontinuity such as an opening, notch, or change of section, where cracks are likely to start.

Cracking that develops under the combined action of tensile stress and a corrosive environment, even below the normal strength of the material.

A system of sensors that measures and displays the stresses and motions of the hull, warning the crew to avoid overloading in heavy weather.

A device for carrying an injured or incapacitated person, part of a ship's medical and rescue equipment.

The outboard strake of a deck, connecting the deck to the sheer strake at the deck edge, an important strength member.

An extra band of paint applied by brush to edges, welds, and corners before or between general coats, because these areas are hard to cover and prone to early breakdown.

The removal of the last residues of liquid from a tank after the main discharge, using stripping pumps or eductors; also the removal of old coating.

The distance a piston travels between its highest and lowest positions in the cylinder.

The examination of the hull structure for corrosion, cracks, and deformation, carried out during surveys to confirm continued integrity. IMO-grounded

A test, such as filling a tank with water, to verify the strength and tightness of the structure, distinct from a leak test.

A structural member that carries compression, such as a bracket supporting the propeller shaft outside the hull.

A system that collects and cleans the oil draining from a stern-tube stuffing box (seal) so that it can be reused or disposed of without polluting the sea. IMO-grounded

An OCR-corrupted term for subdivision, the division of a ship into watertight compartments to limit flooding, governed by SOLAS. IMO-grounded

An OCR-corrupted term for the subdivision index, the measure used in the probabilistic damage-stability rules of SOLAS expressing a ship's attained survivability. IMO-grounded

The draughts used in assessing a ship's subdivision and damage stability under SOLAS. IMO-grounded

The length of the ship used as the basis for the subdivision and damage-stability calculations under SOLAS. IMO-grounded

A high-deposition welding process in which the arc and weld pool are submerged beneath a blanket of granular flux, used for long, straight welds in shipbuilding.

An offshore loading system in which a submerged turret buoy is pulled up into a tanker's hull to make the cargo and mooring connection, allowing operation in harsh weather.

A craft designed to operate underwater, such as a manned submersible or a remotely operated vehicle.

The equipment installed on the seabed in offshore oil and gas production, such as wellheads, manifolds, and pipelines.

Liquids or solids carried loose in bulk in the ship's tanks or holds, regulated under MARPOL and the relevant cargo codes. IMO-grounded

Corrosion that has reduced structural thickness to an extent requiring close monitoring or renewal, defined against criteria in the survey programmes. IMO-grounded

A large cylindrical anchor embedded in the seabed by pumping water out of it, used to moor offshore structures.

A larger or higher-grade cabin or set of rooms, particularly on passenger ships.

A tanker fitted to carry molten sulphur as a heated liquid cargo.

The waterline corresponding to the summer load line, the deepest draught normally permitted in summer zones under the Load Line Convention. IMO-grounded

An anchor design certified to hold with substantially greater power than a standard anchor of the same mass, allowing a reduction in anchor mass under class rules. IMO-grounded

A decked structure on the freeboard deck extending from side to side or nearly so, such as the bridge, forecastle, or poop.

A deck forming the top of a superstructure.

A vessel that carries supplies, equipment, and materials to and from offshore installations; see platform supply vessel.

Air-cushion craft with rigid side hulls and flexible seals at bow and stern, combining catamaran and hovercraft features for high speed.

The condition of the surface of rolled steel, including mill scale and roughness, which affects coating performance and is addressed in surface-preparation standards.

A propeller designed to run partly out of the water, with the blades piercing the surface, used on some high-speed craft.

The cleaning and treatment of a surface before coating, such as blasting and profiling, which largely determines how well the coating will perform.

Recognised standards defining the degree of cleanliness achieved in preparing a steel surface for coating, used to specify and inspect the work.

A boat used to patrol and monitor an area for security, safety, or enforcement.

An examination of a ship, its structure, machinery, or equipment to verify its condition and compliance with rules and conventions; surveys maintain class and statutory certification. IMO-grounded

Small craft used to support survey work, for example carrying surveyors or equipment.

A vessel equipped to carry out surveys, such as hydrographic, geophysical, or geotechnical investigation.

A person qualified to inspect ships and their equipment and to report on their condition and compliance, acting for a classification society, administration, or other party. IMO-grounded

The ability of a ship to remain afloat and stable after damage and flooding, assessed against the damage-stability requirements of SOLAS. IMO-grounded

Craft capable of sustaining the lives of persons in distress from the moment of abandoning ship, such as lifeboats and liferafts, regulated under SOLAS and the LSA Code. IMO-grounded

The plan and arrangement of a ship's survival craft and rescue boats and their launching equipment, as required under SOLAS. IMO-grounded

A proprietary marine evacuation system for transferring people from a ship into survival craft.

Locations in the structure identified as likely to develop corrosion or cracking, marked for close examination during survey. IMO-grounded

The support of a load or system in a way that allows controlled movement or isolation, such as the resilient suspension of machinery.

A partial or perforated bulkhead within a tank that limits the movement of liquid, reducing free-surface effects and sloshing loads.

Seals on a swinging closure such as a door, that seal as the closure is shut.

An azimuth thruster that can be swung up out of the water for maintenance or to reduce draught, while providing propulsion and steering when deployed.

A power converter used in some electric propulsion systems to control synchronous motors.

An alternating-current motor that runs exactly in step with the supply frequency, used in some large drives including electric propulsion.

A proprietary ship lift that raises a vessel vertically out of the water on a platform for repair, an alternative to a dry dock.

Synthetic fuel produced from sources such as gas, coal, or biomass, of interest as an alternative marine fuel.