Maritime Glossary

Source-cited definitions for shipping, engineering, navigation, and regulatory terminology. Confidence-scored and verified against primary IMO, IHO, and industry sources.

Able SeamanAB: An able seaman (AB) is an experienced deck rating who has progressed beyond the entry-level ordinary seaman. ABs stand navigational and mooring watches, act as lookout and helmsman, and carry out the deck maintenance and seamanship tasks that keep the ship running.; seafarersdeckhigh confidence
AframaxAframax tanker: Aframax is a tanker size class of roughly 80,000 to 120,000 tonnes deadweight. The name comes from the Average Freight Rate Assessment (AFRA) system, and these medium-sized tankers carry crude oil and products on shorter and regional routes.; ship-typescommercialhigh confidence
Anchorbower anchor · sheet anchor: An anchor is a heavy device, connected to the ship by a chain cable, that is lowered to the seabed to hold the vessel in position against wind and current. Its holding power comes from digging into the bottom and from the weight and lie of the cable.; seamanshipengineeringoperationshigh confidence
Anchorage: An anchorage is an area of water, often designated by the port or coastal authority, where ships may anchor safely — for example while waiting for a berth, orders, tide, bunkers or inspection. A good anchorage offers shelter, room to swing and reliable holding ground.; portsoperationsnavigationhigh confidence
Automatic Identification SystemAIS: AIS is the Automatic Identification System, a VHF radio system that automatically broadcasts a ship's identity, position, course and speed to nearby vessels and shore stations. It aids collision avoidance, traffic monitoring and ship tracking.; navigationsafetyregulationhigh confidence
BIMCOBaltic and International Maritime Council: BIMCO is the Baltic and International Maritime Council, the world's largest international association representing shipowners, operators, managers and brokers. It is best known for drafting the standard contracts and clauses used across the shipping industry.; commercialorganizationsstandardshigh confidence
Ballastballast water: Ballast is weight (almost always seawater pumped into dedicated tanks) that a ship takes on to keep it stable, safe and correctly trimmed when it is not carrying a full cargo. It is discharged as cargo is loaded and taken on again as cargo is discharged.; operationsenvironmentengineeringhigh confidence
Ballast Water Management ConventionBWM Convention · BWMC: The Ballast Water Management Convention is an IMO treaty requiring ships to manage their ballast water so they do not spread harmful aquatic organisms between regions. Ships must exchange ballast at sea or, increasingly, treat it to an approved biological standard.; regulationenvironmenthigh confidence
Bareboat Charterdemise charter: A bareboat charter, also called a demise charter, hires out a ship without crew or provisions. The charterer takes full possession and control, crewing, operating, maintaining and insuring the vessel for the period, almost as if it were the owner.; commercialcharteringhigh confidence
Beaufort ScaleBeaufort wind force scale: The Beaufort scale is an empirical measure of wind force, running from 0 for calm to 12 for hurricane force. Each number describes the wind by its observable effects on the sea surface and on land, giving mariners a common language for conditions.; navigationmeteorologyseamanshiphigh confidence
Berth: A berth is the place where a ship is moored or lies alongside to load and discharge cargo or embark passengers, such as a quay, wharf, jetty or pier. The word also refers to a crew member's bunk, and to sea room kept clear of a hazard.; portsoperationscommercialhigh confidence
Bill of LadingB/L · BOL: A bill of lading is the central shipping document issued by a carrier for goods received for carriage by sea. It serves three roles at once: a receipt for the cargo, evidence of the contract of carriage, and a document of title to the goods.; commercialcargolegalhigh confidence
Biofoulinghull fouling · marine fouling: Biofouling is the accumulation of marine organisms (algae, weed, barnacles and other growth) on a ship's hull and underwater surfaces. It increases drag and fuel consumption, and can carry invasive species between regions.; environmentengineeringoperationshigh confidence
Bollardbitts · mooring bollard: A bollard is a short, strong vertical post (on a quay, jetty or ship's deck) to which a vessel's mooring lines are made fast to hold it in position alongside. Similar strong posts on the ship itself are usually called bitts.; mooringseamanshipporthigh confidence
Breakbulkbreak-bulk · general cargo: Breakbulk is general cargo that is loaded and carried as individual units or packages (crates, bags, drums, bundles, machinery and project pieces) rather than in containers or as loose bulk. Each item is handled separately, often by crane and sling.; cargooperationshigh confidence
Bulbous Bowbulb bow · bow bulb: A bulbous bow is a protruding bulb-shaped structure at the bow of a ship, just below the waterline. It reduces the ship's wave-making resistance, improving fuel efficiency and speed for vessels operating at their design conditions.; naval-architectureship-designhigh confidence
Bulk Carrierbulker · dry bulk carrier: A bulk carrier is a single-deck ship designed to carry unpackaged dry bulk cargo (such as iron ore, coal, grain, bauxite and cement) loaded loose into large box-shaped holds through wide deck hatches.; vessel-typescargohigh confidence
Bunkermarine fuel · bunker fuel · bunkering: Bunkers are the fuel oils a ship burns for its own propulsion and power, and 'bunkering' is the operation of taking that fuel on board. The term dates from the coal bunkers of early steamships and now covers heavy fuel oil, marine gas oil and newer alternative fuels.; engineeringoperationsdecarbonizationhigh confidence
COLREGSInternational Regulations for Preventing Collisions at Sea · IRPCS · Rules of the Road: The COLREGs are the Convention on the International Regulations for Preventing Collisions at Sea, 1972 — the 'rules of the road' for ships. They set out how vessels must navigate, signal and give way to one another to avoid collision.; navigationsafetyregulationhigh confidence
Cabotagecoastal trade · cabotage law: Cabotage is the carriage of goods or passengers between two ports within the same country. Many countries reserve their cabotage, or domestic coastal trade, to ships that are nationally flagged, built or crewed, to protect their domestic shipping industry.; commercialregulationlegalhigh confidence
Capesizecapesize bulk carrier · cape: Capesize describes very large bulk carriers, typically around 150,000 tonnes deadweight and above, that are too big to transit the Panama or Suez Canals and so must sail the long way around the Cape of Good Hope or Cape Horn.; ship-typescommercialhigh confidence
Capstanmooring capstan: A capstan is a rotating vertical drum, mounted on deck, used to heave on ropes and mooring lines. Its vertical axis distinguishes it from the horizontal windlass, and it is commonly used to help handle mooring lines and warp a ship.; deck-machinerymooringseamanshiphigh confidence
Carbon Intensity IndicatorCII: The CII, or Carbon Intensity Indicator, is an IMO measure of how efficiently a ship carries cargo in terms of carbon emissions. Ships are given an annual operational rating from A to E, and persistently poor performers must take corrective action.; decarbonizationregulationhigh confidence
Charter PartyC/P: A charter party is the contract by which a shipowner lets the use of a ship, or space in it, to a charterer. The main forms are the voyage charter, the time charter and the bareboat charter, each dividing costs and control differently.; commerciallegalcharteringhigh confidence
Classification Societyclass society: A classification society is an independent organisation that sets technical standards for the design, construction and maintenance of ships, and surveys vessels against those rules. A ship 'in class' holds a valid class certificate confirming it meets them.; regulationsafetyorganizationshigh confidence
Cofferdamcoffer dam: A cofferdam is an empty space, or void, built between two compartments of a ship to separate them, preventing the contents of one from leaking into the other and providing a safety barrier, for example between fuel tanks and cargo or accommodation.; ship-structuresafetytankshigh confidence
Container Shipcontainership · box ship: A container ship carries its cargo in standardised intermodal containers stowed in cellular holds and stacked on deck. Capacity is measured in TEU, and the largest vessels now carry well over 24,000 TEU.; vessel-typescargohigh confidence
Deadweight TonnageDWT · deadweight: Deadweight tonnage (DWT) is the total weight a ship can safely carry, in tonnes, the difference between its loaded displacement and its empty lightship weight. It includes cargo plus fuel, water, stores, ballast and crew.; vessel-measurementscommercialhigh confidence
Demurrage: Demurrage is money the charterer pays the shipowner when a ship is kept loading or discharging for longer than the agreed laytime. It compensates the owner for the vessel's lost earning time while it waits in port beyond the allowance.; commercialcharteringlegalhigh confidence
Dispatchdespatch: Despatch, or dispatch money, is a sum the shipowner pays back to the charterer as a reward for completing loading or discharging in less than the allowed laytime. It is the opposite of demurrage, and is usually set at half the demurrage rate.; commercialcharteringhigh confidence
Displacementdisplacement tonnage · ship displacement: Displacement is the actual weight of a ship, equal to the weight of the water it pushes aside, or displaces, when floating. It is the true weight of the vessel and everything aboard at a given moment, measured in tonnes.; naval-architecturestabilityhigh confidence
Double Bottomdouble-bottom tanks · inner bottom: The double bottom is the space between a ship's outer bottom shell and an inner watertight bottom, or tank top. It provides a second skin protecting against flooding after a grounding, and its tanks hold ballast, fuel or fresh water.; ship-structuretanksstabilityhigh confidence
Draftdraught: Draft (or draught) is the vertical distance from the waterline down to the lowest point of a ship's hull, usually the bottom of the keel. It tells you how deep the ship sits and therefore the minimum water depth it needs to float safely.; vessel-measurementsnavigationseamanshiphigh confidence
Dry Dockdrydock · graving dock: A dry dock is a basin that can be flooded to admit a ship and then pumped dry, leaving the vessel supported on blocks with its whole hull exposed. Drydocking allows inspection, repair, painting and survey of the underwater hull and fittings.; engineeringmaintenanceregulationhigh confidence
Dunnagedunnage material: Dunnage is the material (such as timber, boards, mats, bags or matting) placed among and around cargo to secure it, keep it off the deck and away from moisture, allow ventilation, and fill spaces so it cannot shift during the voyage.; cargoseamanshipstowagehigh confidence
Electronic Chart Display and Information SystemECDIS: ECDIS is the Electronic Chart Display and Information System, a computer-based navigation system that displays official electronic charts and the ship's position in real time. Under SOLAS it can replace paper charts as the primary means of navigation.; navigationtechnologyregulationhigh confidence
Emergency Position-Indicating Radio BeaconEPIRB: An EPIRB is an Emergency Position-Indicating Radio Beacon, a distress beacon that, when activated, transmits on 406 MHz to search-and-rescue satellites. It identifies the ship and, with built-in GPS, its position, alerting rescue authorities that a vessel is in distress.; safetynavigationregulationhigh confidence
Emission Control AreaECA · SECA · NECA: An Emission Control Area (ECA) is a sea area where stricter limits on air pollution from ships apply under MARPOL Annex VI. Within an ECA, ships must burn much lower-sulphur fuel or use exhaust cleaning, and in some areas meet tighter nitrogen-oxide limits.; regulationenvironmentdecarbonizationhigh confidence
Energy Efficiency Design IndexEEDI: The EEDI is the Energy Efficiency Design Index, an IMO standard for the design efficiency of new ships. It sets a maximum amount of carbon dioxide a newly built ship may emit per unit of transport work, tightening in phases over time.; decarbonizationregulationenergy-efficiencyhigh confidence
Energy Efficiency Existing Ship IndexEEXI: The EEXI is the Energy Efficiency Existing Ship Index, an IMO measure of the technical, design-based energy efficiency of existing ships. Each ship must meet a required efficiency standard, typically achieved by limiting engine power or improving the vessel.; decarbonizationregulationenergy-efficiencyhigh confidence
Exhaust Gas Cleaning SystemEGCS · scrubber · open-loop scrubber · closed-loop scrubber · hybrid scrubber: A scrubber, or exhaust gas cleaning system, removes sulphur oxides and particulates from a ship's engine exhaust by washing it, usually with seawater. It allows a ship to keep burning cheaper high-sulphur fuel while meeting sulphur emission limits.; engineeringenvironmentdecarbonizationhigh confidence
Fairleadfair-lead · Panama lead · roller fairlead: A fairlead is a fitting on a ship's deck or bulwark that guides a mooring line or rope in the desired direction, giving it a fair, smooth lead to the winch or bollard and reducing chafe and the angle of pull.; mooringseamanshipdeck-fittingshigh confidence
Flag Stateflag · state of registry: A ship's flag state is the country in which it is registered and whose flag it flies. The flag state has legal jurisdiction over the ship, sets and enforces its regulations, and issues or authorises its statutory certificates.; regulationlegaloperationshigh confidence
Floating Production, Storage and OffloadingFPSO: An FPSO is a Floating Production, Storage and Offloading unit — a ship-shaped offshore vessel that receives oil or gas from subsea wells, processes it, stores it on board, and periodically offloads it to shuttle tankers. It brings production to fields far from pipelines.; offshorevessel-typesoil-and-gashigh confidence
Forecastlefo'c'sle · focsle · foc'sle: The forecastle, often written and pronounced fo'c'sle, is the raised deck or structure at the bow of a ship. On modern ships it houses the anchor and mooring machinery and stores, and its raised height helps keep the bow dry in a seaway.; ship-structuredeckseamanshiphigh confidence
Freeboard: Freeboard is the vertical distance from the waterline to the upper edge of a ship's freeboard deck at the ship's side. It represents the reserve buoyancy that keeps a ship afloat and seaworthy, and its minimum is set by the load line.; vessel-measurementssafetyregulationhigh confidence
Gangwayaccommodation ladder · brow: A gangway is the walkway or ladder that provides safe access for people between a ship and the shore, or between a ship and another vessel, when the ship is berthed or alongside. Its use and watch are also part of ship security.; seamanshipsafetyporthigh confidence
General AverageGA: General average is an ancient principle of maritime law under which all parties in a sea venture (ship and cargo owners) share proportionally any loss or expense deliberately incurred to save the whole venture from a common peril.; legalcommercialinsurancehigh confidence
Global Maritime Distress and Safety SystemGMDSS: The GMDSS is the Global Maritime Distress and Safety System, an internationally agreed set of radio equipment and procedures that automates the sending and receiving of distress alerts at sea, so that help can be summoned quickly wherever a ship is.; safetynavigationregulationhigh confidence
Gross TonnageGT: Gross tonnage (GT) is a dimensionless measure of a ship's total internal volume, calculated by an IMO formula. Despite the word 'tonnage' it is not a weight; it is the figure used to size regulatory, safety and commercial requirements.; vessel-measurementsregulationhigh confidence
Hatch Coverhatch covers · cargo hatch cover: A hatch cover is the strong, weathertight cover that closes the opening, or hatch, through which cargo is loaded into a ship's hold. It keeps out sea and rain, protects the cargo, and contributes to the strength and watertight integrity of the deck.; ship-structurecargodeckhigh confidence
Hawsermooring hawser · tow line: A hawser is a large, heavy rope or wire used for mooring or towing a ship. The term is applied to the substantial lines that take the main loads of holding a vessel to a berth or buoy, or of towing one ship by another.; mooringtowingseamanshiphigh confidence
Hong Kong ConventionHong Kong International Convention for the Safe and Environmentally Sound Recycling of Ships · Ship Recycling Convention: The Hong Kong Convention is the IMO's international convention for the safe and environmentally sound recycling of ships. It aims to ensure that ships, when scrapped at the end of their lives, are dismantled without endangering workers or the environment.; regulationenvironmentrecyclinghigh confidence
IMDG CodeInternational Maritime Dangerous Goods Code: The IMDG Code is the International Maritime Dangerous Goods Code, the internationally agreed rulebook for carrying dangerous goods in packaged form by sea. It classifies hazardous cargoes and sets rules for their packaging, marking, documentation, stowage and segregation.; cargoregulationsafetyhigh confidence
IMO GHG Strategy2023 IMO GHG Strategy · IMO decarbonisation strategy: The IMO GHG Strategy is the International Maritime Organization's plan to reduce greenhouse-gas emissions from international shipping. The revised strategy sets the ambition of reaching net-zero emissions from shipping by around 2050, with checkpoints along the way.; decarbonizationregulationenvironmenthigh confidence
IMO NumberIMO Ship ID: An IMO number is a unique seven-digit identifier permanently assigned to a ship's hull for its entire life. Unlike the name, flag or owner, which can change, the IMO number never changes, providing a reliable way to identify a specific vessel.; regulationship-identityhigh confidence
ISM CodeInternational Safety Management Code · SMS: The ISM Code is the International Safety Management Code, which requires shipping companies to operate a documented Safety Management System. Mandatory under SOLAS, it makes safety and pollution prevention a managed, auditable process both ashore and aboard.; safetyregulationmanagementhigh confidence
ISPS CodeInternational Ship and Port Facility Security Code: The ISPS Code is the International Ship and Port Facility Security Code, a mandatory security regime introduced after 2001. It requires ships and port facilities to assess security risks and operate to a plan under three escalating security levels.; securityregulationhigh confidence
Ice Classpolar class · ice strengthening · winterization: Ice class is a notation given by a classification society to a ship that has been strengthened and equipped to navigate in ice. Higher ice classes indicate the ability to operate in thicker ice or more severe conditions, up to dedicated polar classes.; vessel-typesnavigationregulationhigh confidence
International Association of Classification SocietiesIACS: IACS is the International Association of Classification Societies, the body that brings together the world's leading classification societies. It coordinates common technical standards, known as unified requirements, and is the technical adviser recognised by the IMO.; regulationorganizationssafetyhigh confidence
International Maritime OrganizationIMO: The IMO, or International Maritime Organization, is the United Nations specialised agency responsible for the safety and security of shipping and the prevention of pollution from ships. Based in London, it develops the conventions that govern world shipping.; organizationsregulationhigh confidence
Keelship keel · bar keel · bilge keel: The keel is the principal structural member running along the bottom centreline of a ship from bow to stern. It is the backbone of the hull, providing longitudinal strength, and its laying traditionally marks the start of a ship's construction.; naval-architectureship-structurehigh confidence
Knotkn · kt: The unit of speed used at sea and in the air: one knot is one nautical mile per hour, roughly 1.852 kilometres per hour or 1.15 miles per hour. A ship steaming at 12 knots covers 12 nautical miles every hour.; navigationseamanshiphigh confidence
Laytimelay time · lay days: Laytime is the period of time a charter party allows the charterer to load and discharge the cargo without extra payment. If loading or discharging exceeds it the charterer pays demurrage; if it is beaten, the owner may pay despatch.; commercialcharteringhigh confidence
Length OverallLOA: LOA means length overall, the maximum length of a ship measured from the foremost point of the bow to the aftermost point of the stern. It is the length that matters for fitting into berths, locks, dry docks and canal locks.; vessel-measurementshigh confidence
Liquefied Natural GasLNG: LNG is liquefied natural gas — natural gas, mostly methane, cooled to about minus 162 degrees Celsius so that it becomes a liquid occupying roughly one six-hundredth of its gaseous volume. This makes it economic to ship by sea in specialised carriers.; fuelcargodecarbonizationengineeringhigh confidence
Load LinePlimsoll line · Plimsoll mark · International Load Line: The load line, or Plimsoll mark, is a marking on a ship's side showing the maximum depth to which it may legally be loaded. Because the safe limit varies with water density and season, several lines are marked for different zones and conditions.; safetyregulationvessel-measurementshigh confidence
MARPOLInternational Convention for the Prevention of Pollution from Ships: MARPOL is the International Convention for the Prevention of Pollution from Ships, the main IMO treaty controlling pollution of the sea by ships. Adopted in 1973 and modified by a 1978 protocol, it is organised into six technical annexes covering different pollutant streams.; regulationenvironmentpollutionhigh confidence
Maritime Labour ConventionMLC 2006 · MLC: The MLC is the Maritime Labour Convention, 2006, an International Labour Organization treaty often called the seafarers' bill of rights. It sets minimum standards for seafarers' working and living conditions across the world fleet.; seafarersregulationwelfarehigh confidence
Maritime Mobile Service IdentityMMSI: An MMSI is a Maritime Mobile Service Identity, a unique nine-digit number that identifies a ship or a coast station in digital maritime radio communications. It is used by AIS, digital selective calling and other GMDSS equipment to address and identify stations.; navigationsafetyregulationhigh confidence
MasterCaptain · commanding officer: The master is the captain of a merchant ship, the officer in overall command, with ultimate authority and responsibility for the safety of the vessel, everyone aboard, the cargo and the protection of the environment. The master holds overriding authority in an emergency.; seafarersmanagementlegalhigh confidence
Methanol (Marine Fuel)bio-methanol · e-methanol · green methanol: Methanol is an alternative marine fuel: a liquid alcohol that burns more cleanly than heavy fuel oil, producing little sulphur or particulate matter. When made from renewable sources as green methanol, it offers a pathway to lower carbon emissions from shipping.; fueldecarbonizationengineeringhigh confidence
NOxnitrogen oxides · nitric oxide · NO · NO₂: NOx means nitrogen oxides, a group of gases formed when fuel is burned at high temperature in a ship's engines. They contribute to air pollution, acid rain and smog, and are limited on ships by MARPOL Annex VI through progressively stricter tiers.; environmentregulationengineeringhigh confidence
Nautical MileNM · nmi · sea mile: A unit of distance used at sea and in the air, equal to exactly 1,852 metres. It was originally defined as the length of one minute of arc of latitude along a meridian, which ties distance directly to a position on the globe.; navigationseamanshiphigh confidence
Net TonnageNT · net register tonnage · NRT: Net tonnage is a dimensionless measure of a ship's useful cargo-carrying volume, derived from the gross tonnage by deducting the spaces not available for cargo. It is widely used as the basis for port dues, canal tolls and other charges.; commercialregulationhigh confidence
Notice of ReadinessNOR: A Notice of Readiness (NOR) is a formal declaration by the ship that it has arrived at the agreed place and is ready in all respects to load or discharge the cargo. A valid NOR is what starts the laytime clock under a voyage charter.; commercialcharteringlegalhigh confidence
P&I ClubProtection and Indemnity Club · P&I: A P&I Club is a Protection and Indemnity Club, a mutual insurance association owned by its shipowner members that covers third-party liabilities not handled by ordinary hull insurance — such as injury to crew, cargo claims, pollution and collision liability.; insurancecommerciallegalhigh confidence
PanamaxPanamax vessel · Neopanamax · New Panamax: Panamax describes the largest ships that can transit the original locks of the Panama Canal, constrained mainly by the lock dimensions to a beam of about 32.3 metres. The larger Neopanamax size fits the newer, bigger locks opened in 2016.; ship-typescommercialhigh confidence
Passage Planningvoyage planning: Passage planning is the process of preparing a detailed plan for a voyage from berth to berth before the ship sails. Required by SOLAS, it follows four stages (appraisal, planning, execution and monitoring) to ensure the ship follows a safe, pre-considered route.; navigationsafetyregulationhigh confidence
Pilotagemaritime pilotage · compulsory pilotage: Pilotage is the practice of a local navigation expert, the pilot, boarding a ship to advise the master on navigating confined or hazardous waters such as port approaches, rivers and canals. In many such areas pilotage is compulsory.; navigationoperationsregulationhigh confidence
Polar CodeInternational Code for Ships Operating in Polar Waters: The Polar Code is the International Code for Ships Operating in Polar Waters, an IMO instrument setting mandatory safety and environmental requirements for ships in the Arctic and Antarctic. It addresses the extreme cold, ice, remoteness and sensitivity of polar regions.; regulationsafetyenvironmenthigh confidence
Port State ControlPSC: Port State Control (PSC) is the inspection of foreign ships in national ports to verify that they meet international safety, security, pollution and crew standards. Ships that fail can be detained until serious deficiencies are corrected.; regulationsafetyoperationshigh confidence
Port and Starboardport side · starboard side · port · starboard: Port and starboard are the nautical terms for the left and right sides of a ship as seen by a person aboard facing forward, toward the bow. Port is the left side and starboard is the right, and unlike "left" and "right" they never change with the observer's orientation.; navigationseamanshiphigh confidence
Propellerscrew · ship propeller · screw propeller: A propeller is the rotating, bladed device that drives a ship through the water by converting the engine's torque into thrust. As it turns it accelerates water astern, and the reaction pushes the ship forward.; propulsionnaval-architecturehigh confidence
Reeferrefrigerated container · reefer container · refrigerated cargo: A reefer is a refrigerated ship or shipping container used to carry perishable cargo such as fruit, vegetables, meat, fish and pharmaceuticals under precisely controlled temperature, and sometimes controlled humidity and atmosphere, from origin to market.; cargovessel-typeshigh confidence
Ro-RoRoll-on/Roll-off · RORO: Ro-Ro, short for roll-on/roll-off, describes ships that carry wheeled cargo (cars, trucks, trailers and machinery) which is driven on and off the vessel over ramps, rather than lifted by crane. Examples include car carriers and vehicle ferries.; vessel-typescargohigh confidence
Ruddership rudder: A rudder is the flat, movable surface at the stern of a ship, turned by the steering gear, that steers the vessel. By deflecting the water flowing past it, the rudder generates a sideways force that turns the ship.; navigationnaval-architectureship-handlinghigh confidence
SOLASSafety of Life at Sea · International Convention for the Safety of Life at Sea: SOLAS is the International Convention for the Safety of Life at Sea, the most important international treaty on merchant-ship safety. Administered by the IMO, it sets minimum standards for the construction, equipment and operation of ships.; regulationsafetyhigh confidence
SOxsulphur oxides · sulphur dioxide · SO₂: SOx means sulphur oxides, mainly sulphur dioxide, produced when a ship burns fuel that contains sulphur. They cause acid rain and harm health, so their emission is controlled by capping the sulphur content of marine fuel or by cleaning the exhaust.; environmentregulationengineeringhigh confidence
Salvagemaritime salvage: Salvage is the rescue of a ship, its cargo or other property from danger at sea by those under no prior duty to do so. Successful salvors are entitled to a reward, traditionally on a 'no cure, no pay' basis reflecting the value saved and the risk run.; legaloperationssafetyhigh confidence
Search and Rescue Radar TransponderSART · AIS-SART: A SART is a Search and Rescue Radar Transponder, a portable device carried in survival craft. When triggered by a nearby ship's or aircraft's radar, it responds with a distinctive series of blips on the radar screen that guides rescuers to the survivors.; safetynavigationregulationhigh confidence
Slow Steamingsuper slow steaming · speed optimisation: Slow steaming is the practice of operating a ship at a speed well below its maximum to save fuel and cut emissions. Because a ship's fuel consumption rises steeply with speed, a modest reduction in speed produces a large reduction in fuel burned.; operationsdecarbonizationengineeringhigh confidence
Squat Effectsquat · ship squat: Squat is the reduction in a ship's under-keel clearance that occurs when it moves through shallow or confined water. The vessel sinks bodily deeper and changes trim, reducing the gap to the seabed at exactly the point where it is most critical.; navigationseamanshipship-handlinghigh confidence
Stabilityship stability · GM · metacentric height · GZ curve: Stability is a ship's ability to return to an upright position after being heeled over by wind, waves or the movement of weights. It depends chiefly on the arrangement of weights aboard and is commonly assessed through the metacentric height, GM.; seamanshipengineeringsafetyhigh confidence
Standards of Training, Certification and WatchkeepingSTCW: STCW is the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers. Adopted by the IMO in 1978 and substantially updated by the 2010 Manila Amendments, it sets the minimum training and certification every seafarer must hold.; seafarersregulationtraininghigh confidence
SuezmaxSuezmax tanker: Suezmax is a tanker size class describing the largest laden tankers that can transit the Suez Canal, generally around 120,000 to 200,000 tonnes deadweight, constrained mainly by the canal's permissible draught and beam.; ship-typescommercialhigh confidence
Tankeroil tanker · product tanker · chemical tanker: A tanker is a ship built to carry liquid cargo in bulk in its own integral tanks. The category spans crude oil tankers, product tankers, chemical tankers and liquefied gas carriers, each specialised for the cargo it handles.; vessel-typescargohigh confidence
Time CharterT/C: A time charter hires a ship for a period of time rather than for a single voyage. The charterer directs the ship's commercial employment and pays hire plus voyage costs such as bunkers and port charges, while the owner mans and maintains the vessel.; commercialcharteringhigh confidence
Trimlongitudinal trim: Trim is the difference between a ship's draft forward and its draft aft. A vessel is trimmed by the head if deeper forward, by the stern if deeper aft, or on an even keel if the drafts are equal. Trim affects handling, fuel efficiency and hull stress.; vessel-measurementsseamanshipengineeringhigh confidence
Twenty-Foot Equivalent UnitTEU: TEU stands for twenty-foot equivalent unit, the standard measure of container capacity. One TEU is the volume of a standard twenty-foot shipping container, giving the industry a common way to count boxes of different lengths.; cargovessel-measurementscommercialhigh confidence
UN/LOCODELOCODE · UN Location Code: A UN/LOCODE is a code from the United Nations Code for Trade and Transport Locations, a five-character reference that uniquely identifies ports and other transport locations worldwide. It provides a standard shorthand for places in shipping and logistics documents and systems.; portsgeographystandardshigh confidence
UNCLOSUnited Nations Convention on the Law of the Sea · Law of the Sea Convention: UNCLOS is the United Nations Convention on the Law of the Sea, the international treaty that defines the rights and responsibilities of states in their use of the world's oceans. Often called the constitution for the oceans, it sets out maritime zones and freedoms of navigation.; regulationlegalinternational-lawhigh confidence
Very Large Crude CarrierVLCC: A VLCC, or Very Large Crude Carrier, is a crude oil tanker of roughly 200,000 to 320,000 tonnes deadweight. VLCCs carry the biggest single parcels of crude oil on the long-haul export routes; larger still are ULCCs.; vessel-typescargooil-and-gashigh confidence
Vessel Traffic ServiceVTS: A Vessel Traffic Service (VTS) is a shore-based system, run by a port or coastal authority, that monitors and manages ship movements in busy or hazardous waters (much as air traffic control does for aircraft) using radar, AIS and VHF radio.; navigationsafetyregulationhigh confidence
Voyage CharterV/C: A voyage charter is a contract to carry a specified cargo between named ports for a freight rate, with the shipowner operating the vessel and bearing its running costs. The charterer's main time risk is expressed through laytime and demurrage.; commercialcharteringhigh confidence
Voyage Data RecorderVDR · black box · S-VDR: A VDR is a Voyage Data Recorder, the maritime equivalent of an aircraft's black box. It continuously records bridge audio, radar and ECDIS images, position, heading, speed and other data so that the events leading up to an accident can be reconstructed.; safetynavigationregulationhigh confidence
Windlassanchor windlass: A windlass is the deck machinery, mounted on the forecastle, used to raise and lower the anchor and to handle the anchor cable. It has a cable lifter shaped to grip the chain, and usually warping drums for handling mooring lines as well.; deck-machinerymooringseamanshiphigh confidence
WorldscaleWS · New Worldwide Tanker Nominal Freight Scale: Worldscale is a standardised index of nominal freight rates for oil tankers, published for a great many voyage routes. Actual charter rates are negotiated and quoted as a percentage of the Worldscale nominal rate for the route, written as, for example, WS 100.; commercialcharteringoil-and-gashigh confidence