Glossary Archive

An opening in the side of a ship or boat, designed to allow water on deck to drain overboard. In maritime terminology, a scupper is an essential feature of a vessel's design, specifically created to manage water that accumulates on the deck. These openings are typically located along the edges of the deck and are...

A device, typically a canvas or synthetic fabric drogue, deployed in the water to stabilise a vessel by creating drag and reducing drift in rough seas or strong currents. A sea anchor is a critical piece of equipment used in maritime navigation and safety. It is designed to be deployed off the bow or stern of a...

A cooling wind that blows from the sea towards the land, typically occurring during the daytime due to temperature differences between the land and the water. A sea breeze is a meteorological phenomenon that occurs when the sun heats the land and the sea at different rates, creating a temperature gradient. During the day, the...

A stop-cock next to the hull to prevent accidental entry of water

The ability of a person to maintain balance and move steadily on a vessel in motion, particularly in rough seas. Sealegs is a term deeply rooted in maritime culture, describing the adaptation process by which individuals become accustomed to the motion of a boat or ship at sea. When someone has "found their sealegs," it...

The coordinated efforts undertaken to locate and assist individuals in distress or imminent danger, typically at sea, and to bring them to safety.  Search and Rescue (SAR) is a critical operation in maritime environments, designed to respond to emergencies where individuals are lost, injured, or in peril. These operations are often carried out by specialised...

An emergency device that responds to radar signals by transmitting a series of pulses to help rescuers locate a vessel or liferaft in distress.  A Search and Rescue Transponder (SART) is an essential piece of safety equipment used in maritime emergencies to assist in locating vessels, liferafts, or individuals in distress. When activated, a SART...

A location where tidal information is derived by applying corrections to data from a nearby Standard Port.  A secondary port is a coastal location where tidal predictions are calculated by referencing a nearby standard port, which has a full set of tidal data. Since not all ports have their own dedicated tidal observations, secondary ports...

Substitute or repeater flags allow messages with duplicate characters to be signalled without requiring multiple sets of flags.

Occasionally a light may not be visible through 360 degrees, or it may shine different colours depending on where it is viewed from. In this instance the arcs or sectors of visibility and colours will be shown on the chart by dotted lines and a description of the sector such as 'obscured', 'W' (white light),...