Glossary Archive

Removable planks fitted in the cabin entrance to prevent water getting in

A designated period during which a specific crew member or group is responsible for the safe operation and navigation of the vessel. In maritime contexts, a "watch" is a crucial aspect of shipboard life, especially on longer voyages where the vessel is in continuous operation. The crew is divided into shifts, or "watches," ensuring that...

The length of the vessel at the point where it sits in the water. It excludes the total length of the boat, such as features that are out of the water, like a bowsprit. Most boats rise outwards at the bow and stern, so a boat may be quite a bit longer than its waterline...

The vessel’s course through the water, derived from the compass course steered, allowing for leeway but not tide. A line representing the water track is drawn on a chart using a single arrow at its centre, pointing in the direction of travel. Download this crib sheet for all annotations used when plotting vectors on a...

Speed, progress, or momentum through the water. More technically, the point at which there is sufficient water flow past a vessel's rudder for it to be able to steer.

A specific location or reference point on a navigational route, often used to mark progress or changes in course. A waypoint is a predetermined geographical location that is used in navigation to help guide a vessel along a planned route. These points are typically defined by coordinates, such as latitude and longitude, and are entered...

The International Maritime Signal Flag Whiskey. Meaning I require medical assistance.

The tendency of a sailing vessel to turn windward (towards the wind) when under sail, requiring corrective steering to maintain a desired course. Weather helm is a common phenomenon experienced on sailing vessels and is directly related to the balance of forces acting on the boat's sails and hull. It occurs when the centre of...

To lift the anchor from the seabed in preparation for setting sail or moving a vessel. Weighing anchor is a fundamental nautical action that signifies the start of a vessel's journey or a change in its position. The term originates from the Old English word "wegan," meaning "to lift or carry." When a ship is...

A standard in satellite-derived positions. Charts will indicate if they are calibrated to WGS84 or another system. WGS84 is the standard adopted by most cartographers for GNSS (GPS) positions. Established and maintained by the United States National Geospatial-Intelligence Agency since 1984. The NGIA revised it in 2014, however, it retains the reference WGS84. Its pre-cursers were...