Glossary Archive

International Morse Code sequence representing the letter M.

Mean Low Water Neaps (MLWN) is a tidal datum representing the average lowest water level during neap tides. Neap tides occur when the gravitational pull of the sun and moon are perpendicular to each other, resulting in lower high tides and higher low tides. MLWN is used as a reference point for charting and determining...

Mean Low Water Springs (MLWS) refers to the average sea level during low tide under the gravitational influence of the combined forces of the sun and the moon when they are aligned (i.e., during spring tides). This reference level is used in marine navigation and hydrographic surveying to establish a consistent baseline for charting depths...

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

A sailing vessel making way using sails and engine. A downward pointing cone should be displayed in the fore triangle in daylight and lights for power-driven vessel at night. [h5p id="157"]