Maritime Abbreviations
61 abbreviations · part of Transportation & Travel Abbreviations
Abbreviations used for ship name prefixes (USS, HMS, MV), tonnage and container measures (TEU, DWT, GT), international maritime conventions (SOLAS, MARPOL, COLREGS), navigation and safety equipment (AIS, EPIRB) and the shipping trade. Tonnage figures are easy to confuse: gross tonnage measures a ship's enclosed volume, while deadweight measures the weight it can carry. Many of these terms appear in vessel-tracking apps, port notices and news coverage of shipping incidents.
| Abbreviation | Stands for | Description |
|---|---|---|
| AB | Able Seaman | Royal Navy rating at NATO grade OR-2, held by sailors who have completed basic and specialist training. |
| AIS | Automatic Identification System | Radio system that automatically broadcasts a ship's identity, position, course, speed and other data to nearby ships and shore stations. |
| ARPA | Automatic radar plotting aid | Radar feature that tracks other vessels automatically and calculates their course, speed and closest point of approach, warning of collision risks. |
| B/L | Bill of lading | Document issued by a carrier to a shipper acknowledging receipt of goods for shipment, stating the terms of carriage and serving as a document of title that can be… |
| COG | Course over ground | Actual direction a vessel is moving over the seabed, as measured by GPS, which can differ from its heading because of wind, current and leeway. |
| COLREGS | International Regulations for Preventing Collisions at Sea | International "rules of the road" for vessels, setting out who gives way, which lights and shapes to display, sound signals and safe speed. |
| CPA | Closest point of approach | Smallest distance at which two vessels will pass each other if both keep their current course and speed, calculated by radar or AIS. |
| DR | Dead reckoning | Navigation method that estimates a vessel's or aircraft's current position from a known starting point using course, speed and elapsed time, without external fixes. |
| DSC | Digital selective calling | Feature of marine VHF, MF and HF radios that sends automated digital alerts, including a one-button distress call transmitting the vessel's MMSI and position. |
| DWT | Deadweight tonnage | Total weight a ship can safely carry, including cargo, fuel, fresh water, stores, passengers and crew, measured in metric tonnes. |
| ECDIS | Electronic Chart Display and Information System | Approved electronic navigation system that displays official electronic charts with the ship's position, radar overlays and route plans, and can replace paper charts. |
| EPIRB | Emergency position-indicating radio beacon | Distress beacon carried on ships and boats that, when activated manually or automatically by immersion, transmits a 406 MHz signal with the vessel's identity and GPS… |
| FCL | Full container load | Ocean freight booking in which one shipper uses an entire container, packing it at origin and having it delivered sealed to the consignee. |
| FEU | Forty-foot equivalent unit | Measure of container capacity equal to one 40-foot container, or two TEU. |
| FPSO | Floating production storage and offloading unit | Ship-shaped offshore facility that receives oil and gas from undersea wells, processes it, stores the oil and offloads it to tankers. |
| FV | Fishing vessel | Prefix for commercial fishing boats, as in FV Andrea Gail, the swordfishing boat lost in the 1991 storm made famous by "The Perfect Storm." Also written F/V. |
| GMDSS | Global Maritime Distress and Safety System | International system of radio equipment, satellite links and procedures that ensures ships anywhere can send distress alerts and receive safety information. |
| GRT | Gross register tonnage | Older measure of a ship's internal volume, in which one register ton equals 100 cubic feet (about 2.83 cubic meters). |
| GT | Gross tonnage | Dimensionless index of a ship's overall internal volume, calculated under the 1969 International Convention on Tonnage Measurement of Ships. |
| HMAS | His Majesty's Australian Ship | Australian equivalent of HMS, used for commissioned ships of the Royal Australian Navy, as in HMAS Canberra. |
| HMCS | His Majesty's Canadian Ship | Canadian naval prefix placed before the names of commissioned Royal Canadian Navy vessels, as in HMCS Halifax. |
| HMS | His Majesty's Ship | Prefix for ships of the British Royal Navy, as in HMS Queen Elizabeth. |
| IALA | International Organization for Marine Aids to Navigation | Organization that sets worldwide standards for buoys, lighthouses and other marine aids to navigation, including the two buoyage systems, Region A and Region B. |
| IMO | International Maritime Organization | United Nations specialized agency, headquartered in London, that sets global standards for shipping safety, security and pollution prevention. |
| ISM | International Safety Management Code | IMO code requiring shipping companies to run documented safety management systems covering operations, maintenance, emergency preparedness and reporting. |
| ISPS | International Ship and Port Facility Security Code | IMO security code requiring ships and port facilities to assess threats, appoint security officers and implement security plans with set threat levels. |
| LCL | Less than container load | Ocean freight service for shipments too small to fill a container, in which a consolidator combines cargo from several shippers into one container and separates it… |
| LOA | Length overall | Maximum length of a vessel from the foremost to the aftmost point of the hull, including fixed bow sprits or overhangs. |
| MARPOL | International Convention for the Prevention of Pollution from Ships | IMO treaty that limits pollution from ships by oil, chemicals, sewage, garbage and air emissions, set out in six annexes. |
| MLC | Maritime Labour Convention | International Labour Organization convention, adopted in 2006 and in force since 2013, setting minimum standards for seafarers' working and living conditions, including… |
| MMSI | Maritime Mobile Service Identity | Nine-digit number that identifies a ship or coast station on digital selective calling radios, AIS and satellite systems. |
| MOB | Man overboard | Emergency in which a person falls from a vessel into the water, and the alarm call that prompts immediate recovery procedures. |
| MS | Motor ship | Ship prefix, also written M/S, used for diesel-powered vessels, particularly by cruise lines and European ferry companies. |
| MV | Motor vessel | Prefix for a ship powered by an internal combustion engine, usually diesel, the propulsion used by most modern merchant ships. |
| MY | Motor yacht | Prefix for a private yacht powered by engines rather than sails, from small cruisers to superyachts more than 100 meters long. |
| NRT | Net register tonnage | Older measure of a ship's cargo-carrying volume, equal to gross register tonnage minus spaces such as crew quarters, engine rooms and navigation areas. |
| NT | Net tonnage | Measure of a ship's useful cargo or passenger-carrying volume, calculated from the volume of its cargo spaces under the 1969 tonnage convention. |
| NVOCC | Non-vessel operating common carrier | Shipping intermediary that issues its own bills of lading and acts as a carrier to shippers but does not operate ships, instead buying space on ocean carriers' vessels. |
| OOW | Officer of the watch | Deck officer in charge of the ship's bridge and navigation during a watch, responsible for collision avoidance, monitoring the voyage and calling the master when needed. |
| OS | Ordinary seaman | Entry-level deck crew rating on a merchant ship, assisting with watchkeeping, cleaning, maintenance and mooring under the supervision of able seamen. |
| P&I | Protection and indemnity | Marine insurance covering a shipowner's third-party liabilities, such as crew injuries, pollution, cargo damage claims, collision liabilities and wreck removal. |
| PFD | Personal flotation device | Life jacket or buoyancy aid designed to keep a person afloat. |
| RHIB | Rigid-hulled inflatable boat | Fast, seaworthy boat with a solid fiberglass or aluminum hull and inflatable tubes around the sides, used by lifeboat services, navies, coast guards and dive operators. |
| RMS | Royal Mail Ship | Prefix for ocean liners and other ships contracted to carry mail for the British Royal Mail, a mark of prestige for famous liners such as RMS Titanic, RMS Lusitania and… |
| Ro-Ro | Roll-on/roll-off | Ship designed for wheeled cargo, such as cars, trucks and trailers, that is driven on and off via ramps rather than lifted by crane. |
| RV | Research vessel | Prefix for ships used for scientific research, such as oceanography, fisheries surveys or seabed mapping, as in RV Atlantis. |
| SART | Search and rescue transponder | Portable device carried in lifeboats and on ships that responds to rescue radar signals, creating a line of 12 dots on the searcher's radar screen pointing to the… |
| SOG | Speed over ground | Vessel's actual speed relative to the seabed, as measured by GPS, which differs from speed through the water because of currents and tides. |
| SOLAS | International Convention for the Safety of Life at Sea | Most important international treaty on merchant ship safety, covering construction, fire protection, lifeboats, radio equipment, navigation and cargo safety. |
| SS | Steamship | Prefix for a ship propelled by steam engines or steam turbines, used by ocean liners and cargo ships from the 19th century through the mid-20th century. |
| STCW | International Convention on Standards of Training, Certification and Watchkeeping for Seafarers | IMO convention setting minimum training and certification requirements for merchant ship officers and crew worldwide. |
| SV | Sailing vessel | Prefix for a ship or boat propelled primarily by sails, used by tall ships, sail training vessels and cruising yachts. |
| TCPA | Time to closest point of approach | Time remaining until two vessels reach their closest point of approach, displayed by radar and AIS systems. |
| TEU | Twenty-foot equivalent unit | Standard measure of container shipping capacity, equal to one 20-foot shipping container. |
| ULCC | Ultra large crude carrier | Largest class of oil tanker, above about 320,000 deadweight tonnes. |
| USCGC | United States Coast Guard Cutter | Prefix for US Coast Guard vessels 65 feet or longer with permanent crews, ranging from patrol boats to polar icebreakers. |
| USNS | United States Naval Ship | Prefix for noncommissioned ships owned by the US Navy and operated by Military Sealift Command, usually with civilian merchant mariner crews. |
| USS | United States Ship | Prefix for commissioned ships of the US Navy, placed before the ship's name, as in USS Gerald R. |
| VDR | Voyage data recorder | Ship's equivalent of an aircraft black box, recording bridge audio, radio communications, radar images, position, speed, heading and alarms. |
| VGM | Verified gross mass | Confirmed total weight of a packed shipping container, which the shipper must provide to the carrier before the container can be loaded onto a ship. |
| VLCC | Very large crude carrier | Oil tanker of roughly 200,000 to 320,000 deadweight tonnes, able to carry about 2 million barrels of crude. |