Maritime jargon and acronyms explained


Many nautical phrases, acronyms, and abbreviations help to standardise the worldwide nautical language and improve communication on the seas. You may acquire some of the fundamental language needed to travel on the seas, whether you’re a landlubber who dreams of sailing or simply enjoy the sound of nautical phrases, but if you work in the industry, it’s important for you to know the jargon inside and out.


Commonly used phrases

Describing the Vessel:

The first step in understanding the sea-faring lingo is being able to point out the various parts of the ship. Here are all the basics you need to know.

  • Aft – Back half of the vessel
  • Anchor – A large metal weight linked to the vessel by a chain that is thrown overboard to keep it from drifting.
  • Backstays – Lines or cables that hold the mast aloft.
  • Berth – The area on the boat, below deck where they crew sleep.
  • Bilge – The space below the ship’s hull
  • Bow – The front of the ship
  • Bridge – The ships command centre
  • Cleat – A stationary fixture aboard a ship where a rope is secured
  • Fender – A foam or air-filled bumper that prevents boats from colliding with each other or the piers when it’s docked
  • Foot – The base of the sail
  • Galley – The vessels kitchen
  • Mast – The vertical pole that holds rigging or sails in place.
  • Poop deck – The high deck at the back of the vessel
  • Rigging – The structure of lines and the mast
  • Stern – Back half of the ship


Directions at Sea

On a ship, you need to be able to take direct orders from your superiors. Understanding what is being asked of you is essential, because the crew needs to work in sync to ensure the safety of all aboard. Here are some of the terms used to describe directions and positioning on board a vessel.

  • Aboard – On the ship
  • Above board – Above deck level
  • Astern – When the ship travels in reverse
  • Bearing – A horizontal measurement between two points
  • Forward – When the ship travels forwards… Duh!
  • Port – The left side of the ship
  • Starboard – The right side of the ship
  • Upbound – When the ship travels upstream


The Who’s Who of the Ocean

Each person aboard a vessel has a title which helps identify their role at sea. Here are the main crew members you’ll need to know before you set sail.


  • Bar pilot – The crew member in charge of directing the ship through dangerous sandbars
  • Bosun – The officer in responsible for all boat equipment
  • Captain – The most important person on the ship, responsible for everyone and everything aboard
  • Helmsman – The individual in charge of steering the vessel
  • Skipper – The crew member responsible for a small boat
  • Stowaway – Someone who has snuck on board without authorisation
  • Pirate – A bandit who operates at sea


Abbreviations for Marine Equipment, Systems, and Legislation

If you’re traversing the seas water or work within the maritime industry it helps to understand the abbreviated terms and nautical jargon. Here are some of the most common ones to look out for:

  • AIS – Automatic Identification System
  • AMVER – US Coast Guard’s Automated Mutual-Assistance Vessel Rescue System
  • BFI – Baltic Freight Index
  • Bimcosale – Bimco standard form of bill of sale
  • BPI – Baltic Panamax Index
  • DGPS – Differential Global Positioning System
  • DLong – Difference in Longitude
  • DNC – Digital Nautical Chart
  • DOC – Document of Compliance (as per ISM Code)
  • DSV – Diving Support Vessel
  • Dwt – Deadweight Tonnes
  • DX.90 – Format for digital cartographic data
  • ECDIS – Electronic Chart Display and Information System
  • ECS – Electronic Chart System
  • EEZ – Exclusive Economic Zone
  • EN – European Standard
  • EPIRB – Emergency Position Indicating Radio Beacon
  • EPS – IMO performance standard for ECDIS
  • FO – Fuel oil
  • FPSO – Floating Production, Storage and Offloading System
  • FSA – Formal Safety Assessment
  • HO – Hydrographic Office, observed height
  • HP – High pressure
  • HSC – International Code of Safety for High-Speed Craft, IMO
  • HSWA – Health and Safety at Work Act
  • IBCS – Integrated bridge control system
  • IGS – Inert Gas System
  • IICL – Institute of International Container Lessors
  • ISM – Code International Safety Management Code, IMO
  • IS – Information Systems
  • ISSN – International Standard Serial Number
  • IT – Information Technology
  • Lash – Lighter Aboard Ship
  • LOC – Letter of Credit, Letter of Compliance (USCG)
  • LOR – Letter of Readiness
  • LPG – Liquefied Petroleum Gas
  • LR – Lloyd’s Register (classification society)
  • LSA – Life Saving Appliances, Lloyd’s Standard Form of Salvage Agreement
  • LST – Local Standard Time
  • LW – Low Water, Winter Load Line (timber)
  • MAIIF – Marine Accident Investigators’ International Forum
  • Marisat – Maritime Satellite System
  • Mb – Megabyte
  • MDO – Marine Diesel Oil
  • MEO – Medium Earth Orbit (satellite configuration)
  • MERSAR – Merchant Ship Search and Rescue Manual
  • NDT – Non-destructive Testing
  • NFTZ – Non Free Trade Zone
  • OMBO – One Man Bridge Operation
  • OOD – Officer of the Deck, Officer of the Day
  • OOW – Officer of the Watch
  • OPA 90 – Oil Pollution Act of 1990 (USA)
  • OPPR – Oil Pollution Preparedness and Response
  • PSC – Port State Control
  • PV – Pressure/Vacuum, Prime Vertical
  • QA – Quality Assurance
  • RCC – Rescue Coordination Centre
  • RCDS – Raster Chart Display Systems
  • RNC – Raster Navigational Chart
  • SCOPIC – Special Compensation P&I Clause
  • SCR – Special Casualty Representative (P&I)
  • SMC – Safety Management Certificate (as per ISM Code)
  • SPI – Ship-Port Interface, IMO
  • SPM – Single Point Mooring
  • STCW – International Convention on Standards of Training, Certification and Watchkeeping, IMO
  • TFLL – Tropical Fresh Load Line
  • TLL – Timber Load Line
  • TPI – Tonnes Per Inch Immersion
  • UFL – Upper Flammable Limit
  • UPS – Uninterrupted Power Supply
  • UTC – Universal Time (Coordinated)
  • VDR – Voyage Data Recorder
  • VDU – Visual Display Unit
  • WL – Water Line
  • WT – Watertight
  • ZD – Zone Description

We hope this nifty guide will help prepare you for your voyage at sea.

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