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
- A deck rating holding a certificate of competency to serve as a watchkeeping member of the deck crew.
- seafarersdeckhigh confidence
- Anchorbower anchor · sheet anchor
- A heavy metal device attached to the ship by chain cable and dropped to the seabed to hold the vessel in position.
- seamanshipengineeringoperationshigh confidence
- Anchorage
- A designated area of water where vessels may anchor, typically outside a port fairway.
- portsoperationsnavigationhigh confidence
- Automatic Identification SystemAIS
- A VHF transponder system that broadcasts a vessel's identity, position, speed, and course to nearby ships and shore stations.
- navigationsafetyregulationhigh confidence
- BIMCOBaltic and International Maritime Council
- The world's largest international shipping association, producing standard contracts and clauses for the shipping industry.
- commercialorganizationsstandardshigh confidence
- Ballastballast water
- Water taken on board a ship to provide stability and maintain safe trim when cargo spaces are empty or partially loaded.
- operationsenvironmentengineeringhigh confidence
- Ballast Water Management ConventionBWM Convention · BWMC
- IMO convention requiring ships to manage ballast water to prevent the spread of invasive aquatic species.
- regulationenvironmenthigh confidence
- Bareboat Charterdemise charter
- A charter under which the charterer takes full operational and navigational control of the vessel, including crewing and maintenance.
- commercialcharteringhigh confidence
- Beaufort ScaleBeaufort wind force scale
- An empirical measure relating wind speed to observed sea and land conditions, numbered 0 (calm) to 12 (hurricane force).
- navigationmeteorologyseamanshiphigh confidence
- Berth
- A designated place in a port where a vessel moors alongside a quay or pier to load, discharge, or receive services.
- portsoperationscommercialhigh confidence
- Bill of LadingB/L · BOL
- A document issued by a carrier acknowledging receipt of cargo, evidencing the contract of carriage, and serving as a document of title.
- commercialcargolegalhigh confidence
- Biofoulinghull fouling · marine fouling
- The accumulation of micro-organisms, algae, barnacles, and other organisms on a ship's underwater hull.
- environmentengineeringoperationshigh confidence
- Breakbulkbreak-bulk · general cargo
- Cargo individually packaged or unitised (bags, bales, drums, crates) and loaded piece by piece, rather than in containers or as bulk.
- cargooperationshigh confidence
- Bulk Carrierbulker · dry bulk carrier
- A cargo ship designed to carry unpackaged dry bulk commodities such as grain, coal, iron ore, and cement.
- vessel-typescargohigh confidence
- Bunkermarine fuel · bunker fuel · bunkering
- Fuel used to power a ship's main engine and auxiliary machinery, or the act of taking on such fuel.
- engineeringoperationsdecarbonizationhigh confidence
- COLREGSInternational Regulations for Preventing Collisions at Sea · IRPCS · Rules of the Road
- The international rules prescribing how vessels must behave to avoid collisions at sea.
- navigationsafetyregulationhigh confidence
- Carbon Intensity IndicatorCII
- An IMO operational rating that measures a ship's CO₂ efficiency and assigns an annual grade from A (best) to E.
- decarbonizationregulationhigh confidence
- Charter PartyC/P
- A contract between a shipowner and a charterer for the hire of a vessel or cargo space.
- commerciallegalcharteringhigh confidence
- Classification Societyclass society
- A non-governmental organisation that establishes and maintains technical standards for ship design, construction, and maintenance.
- regulationsafetyorganizationshigh confidence
- Container Shipcontainership · box ship
- A cargo vessel designed to carry intermodal shipping containers in standardised cell guides.
- vessel-typescargohigh confidence
- Deadweight TonnageDWT · deadweight
- The total mass a ship can carry when loaded to its maximum permitted draught, including cargo, fuel, ballast, and stores.
- vessel-measurementscommercialhigh confidence
- Demurrage
- A penalty payment owed by the charterer when a vessel is detained in port beyond the agreed laytime.
- commercialcharteringlegalhigh confidence
- Dispatchdespatch
- A reward paid by the shipowner to the charterer for completing cargo operations faster than the allowed laytime.
- commercialcharteringhigh confidence
- Draftdraught
- The vertical distance from the waterline to the lowest point of the hull (keel).
- vessel-measurementsnavigationseamanshiphigh confidence
- Dry Dockdrydock · graving dock
- A narrow basin that is flooded to admit a vessel, then pumped dry for hull inspection and underwater repair.
- engineeringmaintenanceregulationhigh confidence
- Electronic Chart Display and Information SystemECDIS
- An approved navigation system displaying official electronic charts integrated with GPS, radar, and AIS for passage planning and monitoring.
- navigationtechnologyregulationhigh confidence
- Emergency Position-Indicating Radio BeaconEPIRB
- A satellite-linked distress beacon that activates on immersion and transmits the vessel's position to rescue services via the Cospas-Sarsat system.
- safetynavigationregulationhigh confidence
- Emission Control AreaECA · SECA · NECA
- A sea area where stricter limits on SOx, NOx, and particulate matter emissions from ships apply under MARPOL Annex VI.
- regulationenvironmentdecarbonizationhigh confidence
- Energy Efficiency Design IndexEEDI
- An IMO design-based index measuring CO₂ efficiency of a new ship, expressed in grams of CO₂ per tonne-mile.
- decarbonizationregulationenergy-efficiencyhigh confidence
- Energy Efficiency Existing Ship IndexEEXI
- A one-time technical efficiency standard for existing ships under MARPOL Annex VI, in force from November 2022.
- decarbonizationregulationenergy-efficiencyhigh confidence
- Exhaust Gas Cleaning SystemEGCS · scrubber · open-loop scrubber · closed-loop scrubber · hybrid scrubber
- A shipboard system that removes sulphur oxides from engine exhaust gas, enabling compliance with MARPOL Annex VI sulphur limits while burning HFO.
- engineeringenvironmentdecarbonizationhigh confidence
- Flag Stateflag · state of registry
- The country under whose laws a ship is registered, granting nationality and imposing obligations on the vessel.
- regulationlegaloperationshigh confidence
- Floating Production, Storage and OffloadingFPSO
- An offshore vessel that processes hydrocarbons from a subsea reservoir, stores the crude oil on board, and periodically offloads to shuttle tankers.
- offshorevessel-typesoil-and-gashigh confidence
- Freeboard
- The vertical distance from the waterline to the upper surface of the freeboard deck, measured amidships.
- vessel-measurementssafetyregulationhigh confidence
- General AverageGA
- A maritime law principle requiring all parties in a sea venture to proportionally share losses from a voluntary sacrifice made to save the voyage.
- legalcommercialinsurancehigh confidence
- Global Maritime Distress and Safety SystemGMDSS
- The internationally agreed suite of communications equipment and procedures for maritime distress, urgency, and safety communications.
- safetynavigationregulationhigh confidence
- Gross TonnageGT
- A dimensionless measure of a ship's total enclosed volume, used as the basis for port dues, crew regulations, and convention applicability thresholds.
- vessel-measurementsregulationhigh confidence
- Hong Kong ConventionHong Kong International Convention for the Safe and Environmentally Sound Recycling of Ships · Ship Recycling Convention
- The IMO convention setting safety and environmental standards for ship recycling facilities and the decommissioning of vessels.
- regulationenvironmentrecyclinghigh confidence
- IMDG CodeInternational Maritime Dangerous Goods Code
- The international standard for safe carriage of dangerous goods in packaged form by sea.
- cargoregulationsafetyhigh confidence
- IMO GHG Strategy2023 IMO GHG Strategy · IMO decarbonisation strategy
- IMO's revised framework targeting net-zero greenhouse gas emissions from international shipping by or around 2050.
- decarbonizationregulationenvironmenthigh confidence
- IMO NumberIMO Ship ID
- A unique seven-digit identifier assigned permanently to a seagoing merchant ship by the IMO.
- regulationship-identityhigh confidence
- ISM CodeInternational Safety Management Code · SMS
- The IMO code requiring shipping companies and ships to implement a Safety Management System (SMS) to prevent accidents and pollution.
- safetyregulationmanagementhigh confidence
- ISPS CodeInternational Ship and Port Facility Security Code
- The IMO security framework requiring ships and port facilities to implement security plans and designate security officers.
- securityregulationhigh confidence
- Ice Classpolar class · ice strengthening · winterization
- A classification notation indicating the degree to which a vessel has been designed and strengthened to operate in sea ice.
- vessel-typesnavigationregulationhigh confidence
- International Association of Classification SocietiesIACS
- The umbrella body of major classification societies, establishing unified technical requirements for ship construction and maintenance.
- regulationorganizationssafetyhigh confidence
- International Maritime OrganizationIMO
- The UN specialised agency responsible for the safety, security, and environmental performance of international shipping.
- organizationsregulationhigh confidence
- Knotkn · kt
- A unit of speed equal to one nautical mile per hour, universally used in maritime and aviation navigation.
- navigationseamanshiphigh confidence
- Laytimelay time · lay days
- The time allowed by the charter party for loading or discharging cargo without incurring demurrage.
- commercialcharteringhigh confidence
- Length OverallLOA
- The maximum length of a vessel from the extreme forward to the extreme aft point.
- vessel-measurementshigh confidence
- Liquefied Natural GasLNG
- Natural gas cooled to −162 °C until liquid, reducing its volume ~600-fold for storage and transport.
- fuelcargodecarbonizationengineeringhigh confidence
- Load LinePlimsoll line · Plimsoll mark · International Load Line
- A marking on a ship's hull indicating the maximum depth to which the vessel may be legally loaded.
- safetyregulationvessel-measurementshigh confidence
- MARPOLInternational Convention for the Prevention of Pollution from Ships
- The primary international convention preventing pollution of the sea from ships.
- regulationenvironmentpollutionhigh confidence
- Maritime Labour ConventionMLC 2006 · MLC
- The ILO convention establishing minimum international standards for seafarers' working and living conditions.
- seafarersregulationwelfarehigh confidence
- Maritime Mobile Service IdentityMMSI
- A unique nine-digit number identifying a vessel in digital selective calling (DSC) and AIS communications.
- navigationsafetyregulationhigh confidence
- MasterCaptain · commanding officer
- The certified officer holding ultimate command, responsibility, and legal authority over a vessel and all persons on board.
- seafarersmanagementlegalhigh confidence
- Methanol (Marine Fuel)bio-methanol · e-methanol · green methanol
- A liquid alcohol fuel increasingly used as a low- or zero-carbon marine fuel, capable of burning in adapted diesel engines.
- fueldecarbonizationengineeringhigh confidence
- NOxnitrogen oxides · nitric oxide · NO · NO₂
- Nitrogen oxides formed during high-temperature combustion in marine engines, subject to MARPOL Annex VI Tier I/II/III limits.
- environmentregulationengineeringhigh confidence
- Nautical MileNM · nmi · sea mile
- The unit of distance used in navigation, equal to 1,852 metres, defined as one minute of arc of latitude.
- navigationseamanshiphigh confidence
- Notice of ReadinessNOR
- Written notice from the master declaring the vessel has arrived and is ready in all respects to commence cargo operations.
- commercialcharteringlegalhigh confidence
- P&I ClubProtection and Indemnity Club · P&I
- A mutual insurance association providing shipowners with liability coverage for cargo damage, pollution, crew injury, collision, and other third-party claims.
- insurancecommerciallegalhigh confidence
- Passage Planningvoyage planning
- The mandatory berth-to-berth plan covering route, waypoints, safety margins, tidal windows, and contingencies.
- navigationsafetyregulationhigh confidence
- Pilotagemaritime pilotage · compulsory pilotage
- Navigation of a vessel in confined or hazardous waters by a licensed marine pilot with detailed local knowledge.
- navigationoperationsregulationhigh confidence
- Polar CodeInternational Code for Ships Operating in Polar Waters
- The IMO code establishing safety and pollution-prevention requirements for ships in Arctic and Antarctic waters.
- regulationsafetyenvironmenthigh confidence
- Port State ControlPSC
- The inspection of foreign ships in national ports to verify compliance with international conventions.
- regulationsafetyoperationshigh confidence
- Reeferrefrigerated container · reefer container · refrigerated cargo
- A temperature-controlled cargo container or ship used for perishable goods requiring refrigeration.
- cargovessel-typeshigh confidence
- Ro-RoRoll-on/Roll-off · RORO
- A vessel designed for wheeled cargo driven on and off via bow, stern, or side ramps.
- vessel-typescargohigh confidence
- SOLASSafety of Life at Sea · International Convention for the Safety of Life at Sea
- The primary international treaty governing the safety of merchant ships.
- regulationsafetyhigh confidence
- SOxsulphur oxides · sulphur dioxide · SO₂
- Sulphur oxides emitted from burning sulphur-containing marine fuels, regulated under MARPOL Annex VI.
- environmentregulationengineeringhigh confidence
- Salvagemaritime salvage
- A voluntary service rendered to a ship or cargo in peril, entitling the salvor to a reward based on the value of property saved.
- legaloperationssafetyhigh confidence
- Search and Rescue Radar TransponderSART · AIS-SART
- A battery-powered transponder that responds to a 9-GHz ship radar, producing 12 dots on the rescuer's radar to indicate a survivor's position.
- safetynavigationregulationhigh confidence
- Slow Steamingsuper slow steaming · speed optimisation
- Deliberately operating a vessel below its design speed to reduce fuel consumption and CO₂ emissions.
- operationsdecarbonizationengineeringhigh confidence
- Stabilityship stability · GM · metacentric height · GZ curve
- A ship's ability to return to an upright position after being heeled by an external force.
- seamanshipengineeringsafetyhigh confidence
- Standards of Training, Certification and WatchkeepingSTCW
- The international convention setting minimum training, certification, and watchkeeping standards for seafarers.
- seafarersregulationtraininghigh confidence
- Tankeroil tanker · product tanker · chemical tanker
- A bulk-liquid cargo ship carrying oil, chemicals, liquefied gas, or other liquid commodities in integral tanks.
- vessel-typescargohigh confidence
- Time CharterT/C
- A charter under which the owner provides a crewed, maintained vessel for a period at a daily hire rate.
- commercialcharteringhigh confidence
- Trimlongitudinal trim
- The difference between a vessel's aft draft and forward draft.
- vessel-measurementsseamanshipengineeringhigh confidence
- Twenty-Foot Equivalent UnitTEU
- The standard unit of container volume in shipping, based on a 20-foot ISO container.
- cargovessel-measurementscommercialhigh confidence
- UN/LOCODELOCODE · UN Location Code
- A geographic coding scheme for trade and transport locations worldwide, maintained by UNECE.
- portsgeographystandardshigh confidence
- UNCLOSUnited Nations Convention on the Law of the Sea · Law of the Sea Convention
- The international treaty defining the rights and responsibilities of states with respect to the world's oceans.
- regulationlegalinternational-lawhigh confidence
- Very Large Crude CarrierVLCC
- An oil tanker of 200,000–320,000 DWT used on long-haul crude oil routes.
- vessel-typescargooil-and-gashigh confidence
- Vessel Traffic ServiceVTS
- A shore-based monitoring and advisory service managing vessel movements in busy or hazardous ports and waterways.
- navigationsafetyregulationhigh confidence
- Voyage CharterV/C
- A charter under which the owner carries a specific cargo between agreed ports for a freight rate per cargo unit or lump sum.
- commercialcharteringhigh confidence
- Voyage Data RecorderVDR · black box · S-VDR
- A ship's equivalent of an aircraft black box, capturing navigational data, bridge audio, and radar images for accident investigation.
- safetynavigationregulationhigh confidence
- WorldscaleWS · New Worldwide Tanker Nominal Freight Scale
- The reference index for tanker freight rates, expressing the actual rate as a percentage of the nominal Worldscale flat rate for each route.
- commercialcharteringoil-and-gashigh confidence