Glossary Archive

The mean solar time at the Prime Meridian in Greenwich, London, used as a global time standard. Greenwich Mean Time (GMT) is a timekeeping system that started at the Royal Observatory in Greenwich, London, and acts as a reference point for global time zones. It is based on the mean solar time at the Prime...

A type of data format used in oceanography and meteorology to represent gridded data in a binary form for efficient storage and processing. It’s a World Meteorological Organization (WMO) format for packing weather model data (wind, pressure, waves, etc.) into compact binary files. This format involves organising data into a grid structure where each grid...

A type of data format used in oceanography and meteorology to represent gridded data in a binary form for efficient storage and processing. It’s a World Meteorological Organization (WMO) format for packing weather model data (wind, pressure, waves, etc.) into compact binary files. This format involves organising data into a grid structure where each grid...

A general term for the anchors, cables and all the gear required when anchoring

A composite material made of a polymer matrix reinforced with fine glass fibres, commonly used in marine applications for its strength, durability, and resistance to corrosion. Glass Reinforced Plastic (GRP), also known as fibreglass, is a widely used material in the marine industry due to its unique combination of properties. It is created by embedding...

Safety line fitted round the vessel to prevent the crew falling overboard

A safety barrier installed along the edges of a vessel’s deck to prevent crew or passengers from falling overboard. This essential feature on boats and ships usually consists of horizontal wires, ropes, or metal bars supported by stanchions along the deck’s perimeter. Its main purpose is to provide a physical barrier that helps prevent accidental...

The upper edge or rim of a boat's side, often serving as a structural reinforcement and a mounting point for fittings or equipment. The term "gunwale" (pronounced "gunnel") originates from the days of sailing ships when this part of the vessel was reinforced to support the weight and recoil of mounted guns or cannons. Today,...

A rope, wire, or chain used to stabilise or secure a mast, spar, or other structure on a vessel by counteracting lateral forces. A guy is a critical component in the rigging of a ship or sailboat, designed to provide stability and control to masts, spars, and other vertical or angled structures. In maritime contexts,...

A manoeuvre in which a sailing vessel changes course by moving the stern through the wind, causing the sail to shift from one side to the other. A gybe (also spelled "jibe" in American English) is a sailing manoeuvre used when a vessel is running with the wind, meaning the wind is coming from behind...