Marine Abbreviation (L to Q )



Lay Days
The number of days allowed in a charterparty for loading and discharging cargo, or the actual dates between which this can be done.
Lay Days
Cancelling (Laycan)
A charterparty may prescribe two dates as lay days for commencement of loading. The latter of these is a cancelling date in the event that the ship is late in arriving and being ready to load.
The number of lay days permitted in a voyage charter to load or discharge a cargo, taking into account handling capacity and conditions in the port.
See “Carriers Lien”
Liquid Natural Gas Carrier.
Liquid Petroleum Gas Carrier.
Length overall.
An enclosed area of salt or brackish water separated from the open sea by more or less, but not completely, effective obstacles, such as low sandbanks. The name is most commonly used for the area of water enclosed by a barrier reef or atoll.
lanby (Large Automatic Navigational BuoY)
A very large light-buoy, used as an alternative to a light-vessel, to mark offshore positions important to the mariner. Lanbys vary in size up to a displacement of 140 tonnes and a diameter or height of 12 m. Radiobeacons, racons or radar reflectors may be fitted to them. Full details of lanbys are given in Admiralty List of Lights.
land levelling system
A network of benchmarks, etc, connected by levelling to a common datum.
land survey datum
The point of origin of a land levelling system giving the plane to which elevations of features shown on maps are referred. The most usual plane for land survey datums is an approximation to MSL.
The first sight of radar indication of land at the end of a passage.
landfall buoy
A buoy with a tall superstructure, marking the seaward end of the approach to a harbour or estuary. It may be situated out of sight of land.
A place where boats may ground in safety; a contraction of ‘landing place used by boats’. May be artificial, consisting of a platform or steps, or the equivalent in natural rock.
ladding stage
A platform or pontoon connected with the shore, for landing or embarking passengers or goods. Ships can berth alongside the larger landing stages.
Sheltered by land from all or very nearly all directions.
A prominent artificial or natural feature on land such as a tower or church, used as an aid to navigation.
Sliding down of a mass of land on a cliff, mountain or cutting.
lanes; shipping
Much frequented shipping tracks crossing an ocean or sea, launching. The sliding of a newly-built ship by the action of its own weight into the water down on a specially prepared slipway-stern first or beam on (side launch).
launching cradle. The frame in which a ship is supported for launching.
An igneous rock. It is formed by the cooling of magma tie matter flowing from a volcano or fissure in the ground) on the Earth’s surface.
A method of emphasising on a chart differences of height or depth by the use of varying tints.
(Pronounced ‘led’). The weight used in sounding with a leadline. (Pronounced ‘leed’). A narrow channel; especially through pack ice, or in rock or coral-studded waters.
leading lights
Lights at different elevations so situated as to define a leading line when brought into transit.
leading line
A suitable line for a vessel to follow through a given area of water as defined by leading marks located on a farther part of the line.
leading mark
One of a set of two or more navigation marks that define a leading line.
A flat-topped ridge or narrow flat of rocks, extending from an island or coast. cf shelf.
lee shore
The shore towards which the wind is blowing.
lee side
The side of the ship or object which is away from the wind and therefore sheltered.
lee tide
A tidal stream running in the same direction as the wind is blowing.
Large river embankment built to prevent flooding. A naturally raised river bank built up by flood deposit. Oceanographically, an embankment bordering a canyon, valley or channel.
Light Aboard Ship (LASH)
A cargo-carrying system using specially built ships and lighters. Cargoes are loaded into LASH lighters which are towed to a LASH ship where the loaded lighters are embarked. At their destination the LASH lighters are disembarked and towed away to their unloading berths. Special berths or anchorages are sometimes designated for LASH ships.
A beacon from which light is exhibited. cf buoyant beacon.
A buoy carrying a structure from which is exhibited a light, which may have any of the characteristics of a light exhibited from a lighthouse other than sectors. cf lanby, light-float.
An unmanned fully-automated vessel, comparable in size to a light-vessel, or a boat-shaped unmanned float carrying a light and sometimes sounding a fog signal. The former is a major navigational light; the latter may sometimes be used instead of a light-buoy where there are strong tidal streams or currents.
lightening area
See transhipment area.
A general name for a broad flat-bottomed craft used for transporting cargo and other goods between vessels and the shore. Lighters may be self-propelled but are usually towed. There are also lighters rigged for special purposes, cf. dumb lighter, mooring lighter, crane lighter.
A distinctive structure from which a light or lights are exhibited as an aid to navigation.
lighthouse buoy
A name formerly used for a lanby.
A comprehensive term including all illuminated aids to navigation, other than those exhibited from floating structures.
lights in line
Two or more lights so situated that when in transit they define the limit of an area, the alignment of a cable, or an alignment for use of anchoring, etc. Unlike leading lights they do not mark a direction to be followed.
(sometimes known as light-ship). A manned vessel, secured in a designated locality carrying a light of high luminous intensity and usually sounding a fog signal to assist navigation.
A pontoon carrying a ramp placed between a ro-ro vessel and a wharf to enable vehicles to embark or disembark from the wharf.
liquid natural gas (LNG)
Gas, predominantly methane, from oilfield sources. Held in liquid state at atmospheric pressure at a temperature of about -162°C for transport and storage.
liquid petroleum gas (LPG)
Light hydrocarbon material, gaseous at normal temperatures and pressures. By-product of petroleum refining and oil production. Held at liquid state under pressure for transport and storage. Liquid petroleum gases include propane and butane.
local knowledge
The use of a pilot, local seafarer competent to act as a pilot or past experience.
local magnetic anomaly
A magnetic anomaly (qv) covering a small area.
An enclosure at the entrance to a tidal basin, or canal, with caissons or gates at each end by means of which ships are passed from one water level to another without materially altering the higher level. to lock a vessel. To pass a vessel through a lock.
The vague appearance of land, vessels, etc, when first sighted in darkness, or through fog, smoke or haze. Also, the diffused glow of a light seen when the light itself is below the horizon or obscured by an obstacle.
Low Water (LW)
The lowest level reached by the tide in one complete cycle.
low water neaps
See Mean Low Water Neaps.
lower low water
The lower of two successive LWs where diurnal inequality is present.
Lowest Astronomical Tide (LAT)
The lowest tidal level which can be predicted to occur under average meteorological conditions and under any combination of astronomical conditions.
See rhumb line.
lunitidal interval
The time interval between the transit of the Moon and the next following high or low water; hence high water lunitidal interval, low water lunitidal interval, mean high water interval and mean low water interval.


Marine Accident Investigation Branch.
A common form of perforate coral; probably the most wide-spread of reef-building corals.
magnetic anomaly
An effect, permanently superimposed on the Earth’s normal magnetic field and characterised by abnormal values of the elements of compass variation, dip, and geomagnetic force. See abnormal magnetic variation.
magnetic variation
The angle which the magnetic meridian makes with the true meridian. Called ‘magnetic declination’ by physicists.
main ship channel
The channel having the greatest depth and easiest navigation.
A term applied to a major portion of land in relation to off-lying islands.
make the land
Make a landfall (qv). To sight and approach the land after being out of sight of land at sea.
A black mineral used in glass-making, etc, found as a bottom sediment.
mangrove swamp
A flat low-lying area of mud and silt, lying between the high and low water lines of spring tides, covered by the stilt-like roots of the mangrove and associated vegetation. A feature of tropical waters.
An area provided with berthing and shore facilities for yachts.
marine farm
A structure, on the surface or submerged, in which fish are reared or seaweed cultivated. They may obstruct navigation and are sometimes marked by buoys (special) which may be lighted. They are not necessarily confined to inshore locations and may be moved. See also fish haven, fish aggregating device.
marine protected areas
Areas of inter-tidal or sub-tidal terrain together with their overlying waters and associated flora, fauna, historical and cultural features, which have been reserved to protect part or all of the enclosed environment. There is a wide variety of marine protected areas indicated in the terms used such as ‘marine sanctuary’, ‘marine reserve’, ‘marine park’, ‘protected seascape’, or ‘wildlife sanctuary’.
marine railway
A term sometimes applied to a patent slip, more particularly in Canada and the USA.
A fixed feature on land or moored at sea, which can be identified on the chart and used to fix a ship’s position.
A crumbling earthy deposit, particularly one of clay mixed with sand, decomposed shells, etc. A layer of marl is sometimes quite compact.
Mean High Water (MHW)
The average of all high water heights, for a year as defined above. cf High Water. Hence Mean Low Water.
Mean High Water Springs (MHWS)
The height of mean high water springs is the average, throughout a year when the average maximum declination of the Moon is 23.5°, of the heights of two successive high waters during those periods of 24 hours (approximately once a fortnight) when the range of the tide is greatest.
Mean Low Water Springs (MLWS). The height of mean low water springs is the average height obtained by two successive low waters during the same periods.
Mean High Water Neaps (MHWN)
The height of mean low water neaps is the average, throughout a year when the average declination of the Moon is 23.5° of the heights of two successive high waters during those periods (approximately once a fortnight) when the range of the tide is least.
Mean Low Water Neaps (MLWN). The height of mean low water neaps is the average height obtained from two successive low waters during the same periods.
Mean Higher High Water (MHHW)
The height of the mean of the higher of the two daily high waters over a long period of time. When only one high water occurs on a day this is taken as the higher high water. Used where the tide is predominantly diurnal.
Mean Higher Low Water (MHLW)
The height of the mean of the higher of the two daily low waters over a long period of time.
Mean Lower High Water (MLHW)
The height of the mean of the lower of the two daily high waters over a long period of time.
Mean Lower Low Water (MLLW)
The height of the mean of the lower of the two daily low waters over a long period of time. When only one low water occurs on a day this is taken as the lower low water.
Mean Sea Level (MSL)
The average level of the sea surface over a long period, previously 18.6 years, or the average level which would exist in the absence of tides.
Mean Tide Level
The mean of the heights of MHWS, MHWN, MLWS and MLWN.
measured distance
The shortest distance between two or more sets of parallel transits set up on shore to determine the speed of a vessel. The length and direction of the distance are charted.
median valley
The axial depression of the mid-oceanic ridge system. Also called a Rift or Rift Valley.
mid-channel controlling depth
See controlling depth.
The international nautical mile is 1852 m. The unit used by the United Kingdom until 1970 was the British Standard nautical mile of 6080 feet or 1853.18 m.
The sea mile is the length of 1 minute of arc, measured along the meridian, in the latitude of the position; its length varies both with the latitude and with the dimensions of the spheroid in use.
The statute mile is the unit of distance of 1760 yards or 5280 feet (1609.3 m).
The geographical mile is the length of 1 minute of arc, measured along the equator; its value is determined by the dimensions of the spheroid in use.
An annular depression that may not be continuous, located at the base of many seamounts, islands and other isolated elevations.
A breakwater alongside the sheltered side of which vessels can lie. Also, a concrete or stone structure, within an artificial harbour, at right-angles to the coast or the structure from which it extends, alongside which vessels can lie.
Term formerly used for a Single Point Mooring (qv).
To secure a vessel, craft, or boat, or other floating objects by ropes, chains, etc, to the shore or to anchors. Also, to ride with both anchors down laid at some distance apart, and the ship lying midway between them.
mooring buoy
A buoy of special construction which carries the ring of the moorings to which a vessel secures.
mooring lighter
A lighter especially fitted for handling, laying and weighing moorings.
mooring tower
A metal tower standing on the seabed to which ships can moor. Mooring towers are secured to the seabed and surmounted by a turntable to which ships moor. At some mooring towers, a floating hose connects a fluid swivel-assembly in the turntable to the vessel, at others an underwater loading arm carries a pipe from the turntable to the vessel’s midship manifold.
Gear usually consisting of anchors or clumps, cables, and a buoy to which a ship can secure. The moorings. A place in which a vessel may be secured.
Morse code light
A light in which flashes of different duration are grouped in such a manner as to reproduce a Morse code character.
A sediment having predominance of grains with diameters less than 0.06 mm. The term is a general term referring to mixtures of sediments in water and applies to both clays and silts. The geological name is ‘lutite’.


Not always afloat but safely aground – a charterparty provision which allows a ship to rest on the bottom while loading or discharging in a tidal harbour. This assumes that the bottom is soft mud.
Not Negotiable (Non Negotiable)
Either one of these phrases are to be seen stamped or printed on Bills of Lading to state that the rights to the goods shown on the face of the bills cannot be transferred.
Notice of Readiness
The Master’s advice to the charterer in writing that the ship has arrived in port and is in all respects ready to load or discharge.
Notify Party
The name and address entered on a Bill of Lading or a Way Bill, which identifies who is to be informed of the arrival of goods at the destination and will arrange to take delivery on behalf of the consignee.
A contracted part of a channel or river.
natural scale
The ratio between a measurement on a chart or map and the actual distance on the surface of the Earth which that measurement represents. It is expressed as a ratio with a numerator of one, eg 1/25000 or 1:25 000.
nautical mile
See mile.
nautical twilight
The period between the end of civil twilight (qv) and the time when the Sun’s centre is 12° below the horizon in the evening, and the period between the time when the Sun’s centre is 12° below the horizon and the beginning of civil twilight in the morning. cf astronomical twilight.
Affording passage for ships or boats. Also, capable of being navigated.
The art of determining a ship’s position and of taking her in safety from one place to another.
neap tide
A tide of relatively small range occurring near the time of the Moon’s first and last quarters.
neck (of land)
A narrow isthmus or promontory.
no bottom sounding
A depth obtained at which the lead or sounder has not reached the bottom.
nodal point
The point of minimum tidal range in an amphidromic system. An amphidromic point.
noise range
An area set aside for measuring the underwater noise generated by a ship. Acoustic sensing instruments are installed on the seabed with cables leading to a control position ashore. The area is often marked by buoys.
nun buoy
A buoy in the shape of two cones, base to base, and moored from one point so that the other is more or less upright. Used in the USA for a buoy with a conical or truncated conical-shaped top.


Oil/Bulk/Ore carrier.
Oil Record Book
A log kept by the Master of an oil tanker where every discharge or escape of oil is recorded.
observation spot
A position at which precise astronomical observations for latitude and longitude have been obtained.
A danger to navigation, the exact nature of which is not specified or has not been determined.
The great body of water surrounding the land masses of the globe, or more specifically one of the main areas into which the body of water has been divided by geographers. Any of the major expanses of salt water on the surface of the globe.
ocean swell
A swell encountered in the open ocean in great depths.
The study of the oceans especially of the physical features of the sea water and seabed and of marine flora and fauna.
The part of the sea distant but visible from the shore or from an anchorage.
To seaward of, but not close to, the shore, as in ‘offshore fishing’. Also, from the shore, as in ‘offshore wind’. Oceanographically, the region extending seaward from the low water line of Mean Spring tides to the continental or island slope.
offshore installation
Any structure such as a drilling rig, production platform, wellhead, SPM, etc, set up offshore.
ogival buoy
A buoy with an arch-shaped vertical cross-section above the waterline.
Very soft mud, slime; especially on the bed of a river or estuary. Oceanographically, fine-grained soft deposits of the deep-sea, formed from the shells and skeletons of planktonic animals and plants. See diatom, globigerina ooze, pteropod ooze, radiolarian ooze.
Two marks are said to be open when they are not exactly in transit. to open. To bring into view, eg ‘to open the land eastward of a cape’.
open basin
See basin.
open coast
An unsheltered, harbourless coast open to the weather.
open harbour
Unsheltered harbour, exposed to the sea.
open roadstead
An anchorage unprotected from the weather.
open water
Waters where in all circumstances a ship has complete freedom of manoeuvre. cf restricted waters.
A general term to indicate a gap or passage, eg an opening in a reef.
Ordnance Datum
The datum, or series of datums, established on the mainland and adjacent islands of the British isles as the point of origin for the land levelling system.
Ordnance datum (Newlyn). This point of origin corresponds to the average value of MSL at Newlyn during the years 1915 to 1921.
Ordnance Survey
The Government survey of Great Britain; the responsible authority for Ordnance Survey maps.
origin; point of
A fixed point in a co-ordinate system or grid to which all measurements are referred.
A great circle track.
orthomorphic or conformal projection
Charts and maps on this type of projection have the property that small areas on the Earth’s surface retain their shape on the chart or map, the meridians and parallels being at right-angles to one another and the scale at any one point being the same in all directions. Mercator’s and stereographic projections are examples used in hydrography.
outer harbour
A sheltered area, even in bad weather, outside the harbour proper, the inner harbour and the docks.
A narrow outlet of a river into the sea or a lake, as opposed to the opening out at a mouth. Also, the mouth of a sewer or other pipe discharging into the sea.
outfall buoy
Buoy marking the position where a sewer or other pipe discharges into the sea.
Also known as tide-rips. Turbulence associated with the flow of strong tidal streams over abrupt changes in depth, or with the meeting of tidal streams flowing from different directions.
Harmonic constituents of short period, associated with shallow water effect.


Package Limitation under Hague Visby Rules
The limitation of liability of a carrier or shipowner in respect of the value of a unit or package of goods lost or damaged unless its nature and value have been declared before shipment and shown in the Bill of Lading.
Packing List
A note detailing the items contained in a case, crate or parcel. It may be sent inside the package but is often attached to the outside. Copies may be furnished to Customs and sent as advice to the consignees.

The market category of bulk carrier denoting its size in the range of 40,000 to 80,000 tonnes dwt, notionally within the limit for transit of the Panama Canal.

Paramount Clause
In a Bill of Lading or in a charterparty this clause imports the Hague or Hague Visby Rules or the Harter Act and is paramount in that it overrides any clauses which are inconsistent with it.
parallel of latitude
Small circle on the Earth’s surface parallel with the equator.
A comparatively narrow channel often with high ground or cliff on either side, and leading to a harbour or river. Also, a passage through or over a mountain range.
A navigable channel, especially one through reefs or islands. Also, a sea journey between defined points; one or more passages may constitute a voyage.
A portion of water or land which has distinctive characteristics, eg drying patch (of land, ground, sand, etc), shoal patch (of water), and discoloured patch (of water, rock, etc). In British hydrographic usage ‘patch’ may be used as an alternative to ‘shoal’, both being limited to a detached area which constitutes a danger.
patent slip
A cradle supported on carriages running on rails on the shore from about the level of High Water Springs to the level of Low Water Springs. The cradle can be run into the water to receive a small or medium-sized vessel and then hauled up until the vessel is clear of the water for bottom cleaning and repair.
pay off
A ship is said to pay off when her head falls away from the wind.
Water-rounded material of from 4 to 64 mm in size, ie from the diameter of the top of a man’s thumb to the diameter of his clenched fist when viewed sideways.
A series of parallel jetties for berthing small craft.
A small beacon, often an untrimmed sapling, used to mark channels through mud flats or sandbanks; may or may not carry a topmark; often of an impermanent nature.
The point in the orbit of the moon which is nearest to the Earth. When the Moon is in perigee the tidal range is increased, cf apogee.
perigree tide
A spring tide, greater than average, occurring when the Moon is in perigee.
The point in the orbit of a planet which is nearest to the Sun. cf aphelion.
phase (of the Moon)
The appearance at a given time of the illuminated surface of the Moon.
The name formerly applied to bioluminescence.
The microscopic floating plant life of the oceans; the basic food source for most marine life.
A structure, usually of wood, masonry, concrete or iron, extending approximately at right-angles from the coast into the sea. The head, alongside which vessels can lie with their fore-and-aft line at right-angles to the main structure, is frequently wider than the body of the pier. Some piers, however, were built solely as promenades. Also used for the structure joining a wharf to the land.
piers. Supports for the spans of a bridge.
The seaward end of a pier, frequently set at right-angles to the pier in the form of a T or L.
A heavy baulk of timber or a column of reinforced concrete, steel or other material, driven vertically into the bed of the sea or of a river. It may be used to mark a channel or to serve as part support for construction work such as a pier, wharf or jetty.
pile beacon
A beacon formed of one or more piles
pile fender
A pile driven loosely into the seabed in front of a wharf, etc, to absorb the shock of a vessel going alongside.
pile lighthouse
A lighthouse erected on a pile foundation.
pile moorings
Permanent moorings to which a vessel is secured fore and aft between piles.
pillar buoy
A buoy of which the part of the body above the waterline is a pillar, or of which the greater part of the superstructure is a pillar or a lattice tower.
Person qualified to take charge of ships entering, leaving, and moving within certain navigable waters. The term Admiralty Pilot is commonly used to designate a volume of Sailing Directions published by the Hydrographic Office.
The conducting of a vessel within restricted waters. Also, the fee for the services of a pilot.
pilotage waters
Those areas covered by a regular pilotage service.
pinnacle (rock)
A rock, which may or may not be dangerous to navigation, rising sheer from the bottom of the sea, and of which no warning is given by sounding. Oceanographically, any high pillar or rock or coral, shaped like a tower or spire, standing alone or cresting a summit.
Angular motion of a ship in the fore-and-aft plane. cf roll, scend.
The facing of the sloping sides of a breakwater, which may be paved, or consist of stones, tetrapods or rubble.
pivoted beacon or tower
See buoyant beacon.
Oceanographically, a flat gently sloping or nearly level region of the sea floor.
Collective name for the microscopic floating and drifting plant and animal life found throughout the world’s oceans. A distinction can be made between neretic (coastal) and oceanic (deep-water) plankton. See phytoplankton, zooplankton.
Extensive elevated region with level (or nearly level) surface. cf tableland. Oceanographically, a flat or nearly flat area of considerable extent which is relatively shallow, dropping off abruptly on one or more sides.
A sharp and usually comparatively low piece of land jutting out from the coast or forming a turning-point in the coastline.
point of origin
See origin; point of.
Minute creatures of the sea, which always live in colonies, some of which are small and branching and others large and with strong lime skeletons which give them the appearance of corals.
A broad, flat-bottomed floating structure (often of heavy timber baulks) rectangular in shape, used for many purposes in a port, as a ferry landing place, a pierhead, or alongside a vessel to assist in loading or discharging.
A commercial harbour or the commercial part of a harbour in which are situated the quays, wharves, facilities for working cargo, warehouses, docks, repair shops, etc. The word also embraces, geographically, the city or borough which serves shipping interests. See also ports named after location, eg canal port, seaport, river port, etc.
Port Authority
Persons or corporation, owners of, or entrusted with or invested with the power of managing a port. May be called a Harbour Board, Port Trust, Port Commission, Harbour Commission, Marine Department, etc.
port radio station
See radio station.
position line
A line on a chart, representing a line on the Earth’s surface, on which a ship’s position can be said to lie, such as might be obtained from a single bearing, the observations of one heavenly body, or an are of a range circle.
pound (or pond)
Small body of still water in the form of a camber or small basin in a dockyard, used for the storage of boats or other gear afloat. eg boat pound, timber pound.
Licence to hold intercourse with the shore granted to a vessel after quarantine or on showing a clean bill of health.
precautionary area
A routeing measure comprising an area within defined limits where ships must navigate with particular caution and within which the direction of traffic flow may be recommended.
production platform
A permanently-manned offshore structure sited on an oil or gasfield.
project depth
The design dredging depth of a channel.
A geometrical representation on a plane or a part of the Earth’s surface.
prominent object
An object which is easily identifiable, but does not justify being classified as conspicuous.
Oceanographically, a region identifiable by a group of similar physiographic features whose characteristics are markedly in contrast with surrounding areas.
pteropod ooze
Limy deposits formed from the dead bodies of small swimming snails or sea butterflies, commonest near the equator. Found in shallower water than globigerina ooze, and especially near coral islands an on submerged elevations far from land.
A light, porous or cellular type of lava, occasionally to be found floating on the sea surface.


A term applied principally to the Sun and Moon when their longitudes differ by 90″ tie halfway between full and new Moon).
Isolation imposed on an infected vessel. All vessels are considered to be in quarantine until granted pratique (qv).
quarantine anchorage
See anchorage.
Crystalline silica. Usually colourless and transparent, but varies considerably in opaqueness and colour, the most common solid mineral.
A solid structure usually of stone, masonry or concrete (as distinguished from a pile structure) alongside which vessel may lie to work cargoes. It usually runs along or nearly along the line of the shore of the inner part of a port system.
Comprehensive term embracing all the structures in a port alongside which vessels can lie. Also, the charge made for berthing on a quay. cf wharfage.
A wedge; sometimes used to describe the shape of an island or hill.

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