Glossary Archive

A tall, often cylindrical structure equipped with a powerful light and other navigational aids, built near coastlines or on islands to guide mariners and warn them of hazardous areas.  A lighthouse is an essential maritime structure designed to assist in navigation and ensure the safety of vessels at sea. Typically located on prominent headlands, reefs,...

Pronounced: LEE-mah The term for the letter L in the NATO Phonetic Alphabet.

A rope used on a boat for various purposes, such as securing the vessel to a mooring (mooring line), adjusting sails (halyard or sheet), towing another boat (tow line), or for safety purposes (lifeline). Lines are essential tools on a boat and come in different materials, lengths, and thicknesses depending on their intended use.

Navigational lines drawn on a chart, each representing a possible location of a vessel based on a single observation or measurement.  A line of position (LOP) is a fundamental concept in marine navigation used to determine a vessel's location. It is a line on a nautical chart along which a ship is known to be...

A permanent lean to one side or the other

The condition of a vessel leaning to one side due to an imbalance in weight or external forces.  A vessel lists when it tilts to port or starboard due to an uneven distribution of weight, such as cargo, fuel, or ballast, or as a result of flooding. Unlike rolling, which is a temporary motion caused...

Flag semaphore indicating the letter L.

International Morse Code sequence representing the letter L.

An official publication issued by maritime authorities to inform mariners of temporary or permanent changes to navigational aids, hazards, or other critical information affecting local waters. A Local Notice to Mariners (LNM) is a communication tool used by maritime authorities, such as harbourmasters or coastguards, to ensure the safety and efficiency of navigation in specific...

The total length of a vessel measured from the foremost point of the bow to the aftmost point of the stern, including any fixed projections. Length Overall (LOA) is a measurement in the marine industry, as it defines the maximum length of a vessel from end to end. This measurement includes any permanent fixtures such...