W

The disturbed flow of water behind a moving hull, whose pattern affects the flow into the propeller and the ship's resistance.

A duct fitted ahead of the propeller that evens out the wake flow into it, improving efficiency and reducing vibration.

A factor expressing how much slower the water flows into the propeller than the ship's speed, used in propulsion calculations.

The distribution of water velocity in the plane of the propeller behind the hull, important for propeller design and vibration.

The gradual heating of machinery, such as an engine or turbine, before it is put under load, to avoid thermal stress.

The drum on a winch or windlass used for heaving on mooring or warping lines.

The waves and disturbed water created by a moving vessel; also the action of washing a tank.

A perforated or partial bulkhead in a tank that limits the movement of liquid and reduces sloshing; see swash bulkhead.

Machines for washing, including tank-cleaning machines aboard tankers and laundry equipment for the crew.

Material to be discarded, the handling and disposal of which aboard ship is regulated under MARPOL, particularly garbage under Annex V. IMO-grounded

A boiler that raises steam using the heat in an engine's exhaust gas, improving overall fuel efficiency.

The capture of heat from exhaust gas and other sources to generate steam or power, reducing fuel consumption and emissions.

A plan, such as the garbage management plan required under MARPOL Annex V, setting out how shipboard wastes are collected, stored, treated, and disposed of. IMO-grounded

Systems that treat sewage and grey water aboard to a standard allowing discharge, in accordance with MARPOL Annex IV. IMO-grounded

A period of duty aboard ship, and the personnel on duty during it; the keeping of safe navigational and engineering watches is governed by STCW. IMO-grounded

An alarm that confirms the watchkeeper is alert, raising warnings and calling for assistance if not acknowledged. IMO-grounded

The bridge navigational watch alarm system (BNWAS) that monitors the officer of the watch's alertness and raises an alarm if the watch becomes incapacitated, required under SOLAS. IMO-grounded

A screen of water spray used to protect a surface or boundary from heat and fire, for example on a tanker's accommodation front.

A fine spray of water used to cool and smother a fire while limiting the amount of water applied.

A device showing the water level in a boiler or tank.

A barrier formed by a body of water that prevents the passage of gas, as in the deck seal of an inert-gas system on tankers. IMO-grounded

A fire-fighting medium of water in droplets, used in fixed water-spray systems to protect spaces such as vehicle decks and machinery, under SOLAS and the FSS Code. IMO-grounded

A fixed water-spray or water-mist system protecting a specific high-risk area such as around engines and boilers, required under SOLAS. IMO-grounded

A propulsion device that draws in water and expels it astern at high velocity to produce thrust, used on fast craft for speed and manoeuvrability.

Propulsion by waterjets, giving high speed, good shallow-water capability, and precise low-speed control.

The line where the surface of the water meets the hull, varying with loading and trim.

The area of the horizontal section of the hull at the waterline, which governs the ship's resistance to changes of draught and its initial stability.

Capable of preventing the passage of water under the pressure head that may occur in service, a standard required of subdivision boundaries and their closures under SOLAS. IMO-grounded

A door in a watertight bulkhead that maintains watertight integrity when closed; its type, control, and operation are regulated by SOLAS. IMO-grounded

Doors that preserve the watertight integrity of bulkheads, with requirements for their construction, indication, and remote operation under SOLAS. IMO-grounded

A plan showing the ship's watertight boundaries, openings, and their means of closure, supporting the maintenance of watertight integrity and damage control. IMO-grounded

A disturbance travelling across the water surface, the principal source of the dynamic loads and motions a ship experiences at sea.

A measure of the range of wave-induced motion over which a fin stabiliser remains effective in reducing roll.

The gradual loss of material from a surface through friction, abrasion, or erosion in service.

A gauge used to measure the wear (weardown) of a bearing, such as a stern-tube bearing, to assess its condition.

A radio service and receiver that prints weather charts aboard ship, supporting passage planning and heavy-weather avoidance.

A deck exposed to the weather and sea, whose openings must be capable of being closed weathertight under the Load Line Convention. IMO-grounded

Capable of preventing the passage of water into the ship in any sea condition, the standard required of weather-deck closures under the Load Line Convention. IMO-grounded

A door that prevents the entry of water in any sea condition, required for openings in exposed positions under the Load Line Convention. IMO-grounded

The flat part of a structural member between its flanges, such as the web of a girder or floor.

A deep, strong transverse frame that supports the ordinary frames and stiffens the structure at intervals.

A cleat that secures a hatch cover or closure by driving a wedge to tighten it against its seal.

Imperfections in a weld, such as cracks, porosity, lack of fusion, slag inclusions, and undercut, which may reduce its strength and are limited by acceptance criteria.

Preferential corrosion of the weld metal relative to the surrounding plate, which can occur where their compositions differ.

The ease with which a material can be welded to produce sound joints with the required properties.

A person who joins metal by welding.

The formal qualification of a welder, by test, to perform welding to a given standard, required for structural work.

A test weld made by a welder to demonstrate the skill to produce sound welds of a particular type and position.

The joining of metals by fusing them together, with or without filler metal, the principal method of building steel ships.

Equipment that provides and controls the power for welding.

A person who operates mechanised or automatic welding equipment.

A documented and qualified method specifying how a particular weld is to be made, including the process, materials, and parameters.

The order in which welds are made to control distortion and residual stress in a structure.

The contraction of weld metal and surrounding material as it cools, which causes distortion that must be allowed for.

The characteristics of the oil, gas, and water produced from a well, which influence the design of offshore processing and handling.

An offshore vessel equipped to enter and service subsea wells without a drilling rig, for maintenance and repair.

The servicing and repair of oil and gas wells to keep them producing.

Equipment used to test the flow and characteristics of a well, often aboard offshore vessels and units.

The equipment at the top of a well, on the seabed or a platform, that controls and connects to the well.

The thickness of a coating immediately after application while still wet, measured to ensure the correct dry film thickness will result.

A propeller-shaft arrangement in which the stern-tube bearings are lubricated by seawater rather than oil.

A small submersible in which the occupants are exposed to the water and breathe from apparatus, as opposed to a dry, pressurised one.

A device that inspects the underwater hull surface while the ship is afloat, for example to assess fouling and coating condition.

The area of the hull in contact with the water, which determines the frictional resistance.

An OCR-rendered proprietary name (Columbus), likely a vessel or system designation.

The enclosed part of the bridge from which the ship is steered and navigated.

A poster displayed in the wheelhouse summarising the ship's manoeuvring characteristics for quick reference, recommended by the IMO. IMO-grounded

A sound-signalling appliance used to make the signals prescribed by the collision regulations (COLREGs). IMO-grounded

A soft bearing alloy, usually tin- or lead-based, lining bearings to provide a low-friction surface.

The lighter, clean refined petroleum products such as gasoline, kerosene, and gas oil, as distinct from dark (black) oils.

A tow whose width exceeds normal limits, requiring special precautions and lights.

A powered drum machine used to haul on ropes or wires for mooring, cargo, or other purposes.

The strakes of side shell plating around the waterline, alternately wetted and exposed, which are particularly prone to corrosion.

A vessel or unit equipped to inspect, maintain, and repair offshore wind turbines.

A specialised offshore vessel for installing, servicing, and repairing wind turbines, often with a jack-up capability and heavy-lift crane.

The deck machine used to raise and lower the anchor and its cable, and often to handle mooring lines.

Trials demonstrating that the windlass can hoist the anchor and cable at the required speed and hold the design load.

Glazed openings in the superstructure and deckhouses; those in exposed positions must meet strength and, where required, weathertight standards. IMO-grounded

The direction from which the wind is blowing; the side of the ship facing the wind.

A craft that flies just above the surface supported by ground effect; the IMO has developed guidelines for WIG craft operating over water. IMO-grounded

A tank located at the side of the ship, used for ballast or cargo and, on double-hull tankers, helping protect the cargo tanks from side damage. IMO-grounded

A machine that spools wire onto or off a drum in a controlled manner.

A drawing showing the connections of an electrical system.

A small, versatile vessel used for harbour and offshore tasks such as towing, line handling, and support.

A raft used as a working platform, for example alongside the hull or in offshore operations.

The standard of skill and care with which work, such as welding and coating, is carried out, affecting the quality and durability of the result.

Major maintenance or repair work carried out on an oil or gas well to restore or improve its production.

A space aboard equipped with tools and machines for maintenance and repair work.

A position equipped for a particular function, such as a bridge navigation or monitoring workstation.

A ship that has been sunk, stranded, or destroyed, the removal of which may be required for safety and is addressed by international convention. IMO-grounded

The condition of a ship that has been wrecked or has run aground and is held fast.