Glossary Archive

Flag semaphore indicating the letter M.

International Morse Code sequence representing the letter M.

The average height of low tides during neap tide cycles, which occur when the tidal range is at its smallest due to the reduced gravitational pull of the sun and moon. Mean Low Water Neaps (MLWN) is a tidal datum used in marine navigation and coastal management to describe the average level of low water...

The average level of the lowest low tides that occur during spring tide conditions, calculated over a standard period of time. Mean Low Water Springs (MLWS) is a tidal datum used in marine navigation, hydrography, and coastal engineering. It represents the average height of the lowest tides that occur during spring tides, which are the...

A unique nine-digit number assigned to a vessel, coast station, or group of stations for digital communication and identification in the Global Maritime Distress and Safety System (GMDSS). Maritime Mobile Service Identity (MMSI) is a critical component of modern maritime communication systems, enabling efficient and precise identification of vessels and stations during radio communications. This...

A solid structure, often made of stone or concrete, built to protect a harbour, anchorage, or shoreline from the effects of waves and currents, and sometimes used as a pier for docking vessels. A mole is a significant maritime structure designed to serve as a barrier against the forces of the sea, such as waves,...

A vessel with a single hull

A permanent structure or equipment, such as a buoy, anchor, or dock, used to secure a vessel in place or the act of securing a vessel to a fixed point, such as a buoy, dock, or anchor, to prevent it from drifting Mooring refers to the act of securing a boat or ship to a...

A non-navigational floating device anchored to the seabed, used for securing vessels in place without the need for traditional anchoring. A mooring buoy is a specialised type of buoy designed to provide a secure point for vessels to tie up to, often used in harbours, marinas, or designated mooring fields. Unlike navigational buoys, which are...

A ring on a mooring buoy