Glossary Archive

A gated section of a waterway, such as a canal or river, designed to raise or lower vessels between stretches of water at different levels. A lock is an essential feature of many inland waterways, enabling vessels to navigate areas where the water level changes due to natural gradients, tides, or man-made structures such as...

A storage compartment or enclosed space on a boat, typically used for stowing equipment, gear, or provisions securely. A locker on a boat is a storage area designed to keep various items safe, dry, and organised while at sea. These compartments are often built into the structure of the vessel, such as under seats, within...

An official record maintained aboard a vessel that documents the ship's daily activities, including navigational data, weather conditions, and significant events. A logbook, also known as a ship's log or deck log, is a crucial document on any vessel, whether it be a commercial ship, naval vessel, or recreational boat. It serves as a comprehensive...

A device used historically by mariners to measure a vessel's speed through the water. The log line consists of a wooden board, known as the log, attached to a long, knotted rope. The log was thrown overboard and allowed to float behind the ship while the rope was paid out. Mariners would measure the vessel's...

The reading of distance travelled through the water usually taken every hour from the log and recorded in the deck log

The geographic coordinate that specifies the east-west position of a point on the Earth's surface, measured in degrees(°), minutes(') and seconds(") from the Prime Meridian. Longitude is one of the two key coordinates used in navigation and mapping to determine a specific location on the Earth's surface. The other is latitude. While latitude measures how...

A crew member assigned to maintain a continuous watch for potential hazards, other vessels, or navigational markers while at sea. A look-out is a critical role in maritime operations, ensuring the safety of the vessel and its crew by maintaining vigilance for any potential dangers or navigational aids. The look-out is typically stationed at a...

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 vessel loses way when she slows down and stops in the water

The lowest level that sea tides can reach under normal meteorological conditions, based on astronomical influences such as the gravitational pull of the moon and sun. Lowest Astronomical Tide (LAT) is a tidal datum used as a reference point for charting and navigation. It represents the lowest predicted tide level that can occur due to...