L

A means of climbing between levels aboard ship; various types (accommodation, pilot, embarkation, vertical) are subject to construction and safety requirements.

A voyage made with cargo aboard, as opposed to a ballast (empty) voyage.

Insulating material applied around pipes, boilers, and vessels to reduce heat loss, with a protective outer covering.

Ships taken out of active service and laid up, usually because of poor market conditions.

A vessel built for and trading on the Great Lakes, of dimensions suited to the lakes and their locks.

Smooth, orderly fluid flow in parallel layers without mixing, as opposed to turbulent flow; relevant to the flow over the forward part of a hull.

A flaw in rolled steel plate consisting of an internal separation parallel to the surface, detected by ultrasonic testing.

Conspicuous features ashore used by mariners to fix position and aid navigation.

A joint in which one member overlaps another, the two being welded along the edge of the overlap.

A barge-carrier system in which loaded lighters (barges) are lifted aboard a mother ship for ocean carriage and floated off at destination.

The securing of cargo or equipment with ropes, wires, chains, or straps to prevent movement in a seaway.

A raised athwartship structure on a container ship from which containers stowed on deck are lashed, giving access to higher tiers.

The heat absorbed or released when a substance changes state, such as from liquid to vapour, without a change in temperature.

Sideways instability of a structural member under load, in which it bows out of its plane.

A water-based dispersion of polymer particles used as a binder in some paints and coatings.

To put a newly built ship into the water for the first time; also a small powered boat.

The equipment used to deploy and retrieve an underwater vehicle, diving bell, or tool from a vessel, controlling it through the splash zone.

The deployment of a ship into the water on completion of building, or of survival craft from a ship.

The davits, falls, and gear used to lower a survival craft to the water in a controlled manner; required and regulated under SOLAS and the LSA Code. IMO-grounded

The supporting cradle on which a vessel is held and slides during a launch.

The angle of the ramp from which a free-fall lifeboat is launched, a factor in the boat's certification and safe water entry. IMO-grounded

The length of the ramp down which a free-fall lifeboat slides during launching, affecting its entry into the water.

The arrangement of spaces, equipment, and systems within the ship or a part of it.

The time allowed under a charter party for loading or discharging the cargo, beyond which demurrage may be payable.

A pair of navigational marks or lights aligned to indicate a safe line of approach when kept in line (a transit).

The escape of fluid through a defect or imperfect seal.

A gas or dual-fuel engine that burns a fuel-air mixture with excess air, lowering combustion temperature and reducing nitrogen-oxide emissions.

The defined length of a ship used for regulatory and design purposes, which under several conventions is taken as a percentage of the waterline length or the length between perpendiculars. IMO-grounded

The length of the hull measured along the design waterline, from the forward to the after end of the immersed form.

The greatest length of the ship measured from the foremost to the aftermost point of the hull.

The equipment provided to save and preserve life in an emergency, such as lifeboats, liferafts, lifejackets, and lifebuoys; their standards are set by SOLAS and the LSA Code. IMO-grounded

The complete arrangement of life-saving appliances and their launching and support equipment provided aboard a ship under SOLAS. IMO-grounded

A rigid survival craft capable of sustaining the lives of persons in distress from the time of abandoning ship; its construction, capacity, and equipment are regulated by SOLAS and the LSA Code. IMO-grounded

The davits that hold, swing out, and lower a lifeboat; their design and operation are governed by SOLAS and the LSA Code. IMO-grounded

The designated deck position from which a lifeboat is boarded and launched.

A buoyant ring thrown to a person in the water to keep them afloat; required numbers, locations, and fittings (lights, lines) are set by SOLAS and the LSA Code. IMO-grounded

A buoyant personal device worn to keep a person afloat with the head clear of the water; required for all persons aboard under SOLAS and the LSA Code. IMO-grounded

An inflatable or rigid survival craft that deploys to carry survivors; its construction, equipment, and stowage (including float-free arrangements) are regulated by SOLAS and the LSA Code. IMO-grounded

The survival equipment carried in a liferaft, such as paddles, bailers, signals, and rations, specified by the LSA Code. IMO-grounded

The line connecting a liferaft to the ship that, on a float-free raft, both deploys and inflates it and then releases it as the ship sinks. IMO-grounded

A hatch cover that is lifted clear of its seating and then rolled aside to open the hatch.

Hatch covers in which one panel is lifted and stacked onto an adjacent panel (piggy-back) to open the hatch.

A hatch cover that is lifted off entirely by crane and set aside to open the hatch.

Hatch covers removed completely by crane, rather than rolling or folding, to open the hold.

Movable vehicle decks that can be raised or lowered to adjust clear height for different vehicles.

A rigid beam used in lifting to spread a load between two or more lifting points and control the geometry of the lift.

Crude oil of low density and viscosity, which flows easily and yields a high proportion of light products.

A hole cut in a structural member to reduce weight without unduly reducing strength, also providing access and drainage.

The transfer of cargo from one ship to another, often at anchor, to reduce a vessel's draught so it can enter port; see ship-to-ship transfer.

A barge used to carry cargo between ship and shore or to transfer cargo between ships.

The carriage of cargo by lighter, and the charge for it.

The loading condition with the least displacement in which a ship goes to sea, used in stability and strength assessment.

Fixed shore structures showing a powerful light to guide and warn mariners, part of the system of aids to navigation.

The provision of illumination aboard ship, including normal and emergency lighting; emergency lighting of escape routes and key spaces is required by SOLAS. IMO-grounded

The ship complete and ready for service but without cargo, fuel, stores, ballast, crew, or passengers; its weight and centre of gravity are the basis of stability calculations.

The draught of the ship in the lightship condition.

The mass of the ship in the lightship condition, determined by an inclining test or lightweight survey.

A coefficient relating the lightship mass to the ship's principal dimensions, used for estimating in early design.

Moored vessels showing a light to mark a hazard or channel where a fixed lighthouse is impractical.

A survey to verify a ship's lightship weight and centre of gravity by measuring draughts and accounting for items aboard, often done in place of a full inclining test on a sister ship. IMO-grounded

A small hole in a floor or frame at the bottom of the structure that allows water to drain along to the bilge suction.

A device that fires a light line to another ship or the shore to establish a connection, for example for rescue or towing; required as life-saving equipment under SOLAS and the LSA Code. IMO-grounded

An association of liner shipping companies that agree on rates and conditions on a trade route.

A regular, scheduled cargo or passenger service operating between fixed ports, as opposed to tramp shipping.

The drawing that defines the shape of the hull through its waterlines, buttocks, and sections, the basis for fairing the form and for all naval-architectural calculations.

A movable bridge or ramp ashore that connects to a ro-ro ship's ramp to allow vehicles to drive on and off across the changing tide.

A shaft seal using a flexible lip pressed against the shaft to retain lubricant and exclude water, used in stern tubes and other shaft seals.

The change of a gas into liquid by cooling or compression; also the process by which a solid bulk cargo with moisture can behave like a liquid and shift dangerously, a hazard addressed by the IMSBC Code. IMO-grounded

Natural gas, mainly methane, cooled to about minus 162 degrees Celsius so that it becomes liquid for transport in specialised tankers built to the IGC Code. IMO-grounded

Propane, butane, or their mixtures, liquefied by cooling or pressure for transport in gas carriers built to the IGC Code. IMO-grounded

Cargo carried in liquid form in tanks, such as oil, chemicals, or liquefied gas, governed by MARPOL and the relevant cargo codes. IMO-grounded

Waste liquid chemicals requiring controlled handling and disposal to prevent pollution, addressed under MARPOL. IMO-grounded

A non-destructive test in which a penetrating liquid reveals surface-breaking defects; see dye penetrant testing.

The loading, discharging, and internal transfer of liquids such as cargo, bunkers, and ballast, carried out under controlled procedures to prevent spills.

A steady transverse inclination of a ship due to an unsymmetrical distribution of weight or to flooding.

Lights or indicators showing the ship's angle of list, used during cargo and ballast operations.

Ships fitted to carry live animals, with pens, ventilation, feeding, watering, and waste systems for the welfare of the animals.

The tank and insulation systems that hold LNG at very low temperature aboard a carrier, of membrane or self-supporting (independent-tank) types built to the IGC Code. IMO-grounded

A ship designed to carry liquefied natural gas in insulated low-temperature tanks, built to the IGC Code. IMO-grounded

An LNG carrier fitted to regasify its cargo aboard and deliver natural gas ashore through a connection, acting as a floating import terminal.

The International Convention on Load Lines, which sets the minimum freeboard and related requirements limiting how deeply a ship may be loaded, marked by the load line on the ship's side. IMO-grounded

The marking on a ship's side, including the Plimsoll disc and lines, showing the maximum permitted draughts in different zones and seasons, assigned under the Load Line Convention. IMO-grounded

Equipment used to load cargo, such as a shiploader at a bulk terminal.

The operation of putting cargo aboard a ship, planned to control stability, trim, and hull stresses.

The approved manual, required under SOLAS and the Load Line Convention, giving the master information on loading the ship safely within stability and strength limits. IMO-grounded

Articulated pipe arms at a terminal that connect to a tanker's manifold to transfer liquid cargo, replacing flexible hoses.

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

The loading of a tank from the top, with the inlet discharging above the liquid level, which can generate static electricity and is restricted on tankers for safety. IMO-grounded

The rate at which cargo is loaded, limited so that tank venting, structure, and safety arrangements are not overtaxed.

The forces and pressures acting on a ship's structure, from cargo, the sea, and operations, which the design must withstand.

The operation of machinery directly at the equipment itself, rather than remotely from a control room.

Fixed fire-protection arrangements covering a specific high-risk area, such as a water-mist or other system protecting around boilers, incinerators, and engines, required under SOLAS. IMO-grounded

Corrosion concentrated at specific spots, such as pitting or grooving, rather than spread evenly, which can cause perforation while overall thickness loss is small.

The position of something aboard or geographically.

An enclosure with gates in a waterway or canal used to raise or lower vessels between water levels; also a securing device.

The full-size or scaled laying-out of a ship's lines and structural parts to develop accurate shapes for fabrication, now done largely by computer.

An instrument that measures a ship's speed and distance through the water; also a record such as the deck or engine log.

The official book in which the events, navigation, and operations of the ship are recorded.

A hull-form coefficient relating the underwater volume to the product of the midship section area and the length, indicating how the volume is distributed along the length.

Fore-and-aft structural stiffeners attached to the shell, deck, and bottom plating that contribute to longitudinal strength in a longitudinally framed hull.

A fishing vessel that catches fish using long lines carrying many baited hooks.

Cargo-securing fittings that are not permanently attached, such as twistlocks and lashing rods, used and stowed as needed.

An arrangement of angled slats that admits air while excluding rain and spray, used in ventilation openings.

Describing surface materials that resist the spread of flame across their surface, required for exposed surfaces in accommodation and other spaces under SOLAS. IMO-grounded

The net calorific value of a fuel, the heat released by combustion excluding the heat that would be recovered by condensing the water vapour produced.

Engine combustion techniques that reduce the formation of nitrogen oxides, helping to meet the limits of MARPOL Annex VI. IMO-grounded

Fire-fighting foam of low expansion ratio that flows readily over a liquid surface to form a sealing blanket, used for tank-deck and spill fires.

A hydraulic drive operating at relatively low pressure.

A large two-stroke diesel engine running at low rotational speed, coupled directly to the propeller, the dominant main engine for large merchant ships for its efficiency.

The lowest concentration of a flammable vapour in air that will ignite; below it the mixture is too lean to burn, a key value in tanker gas control. IMO-grounded

A ship designed to carry liquefied petroleum gas in bulk under pressure or refrigeration, built to the IGC Code. IMO-grounded

Oil used to reduce friction and wear between moving parts and to cool, clean, and protect them.

The supply of a lubricant between moving surfaces to reduce friction, wear, and heat.

A proprietary low-friction pad used in launching or sliding arrangements.

To bring a sailing vessel's head closer to the wind; more generally, to alter course toward the wind.

A ship designed or fitted to carry timber and packaged lumber, including substantial deck cargoes secured under the timber deck cargo code. IMO-grounded

A complete light fitting, including the lamp and its housing and controls.

The measured brightness of a surface as perceived, important in the design of displays and lighting.