Glossary Archive

The speed at which a vessel is effectively moving towards its intended destination, factoring in both its current speed and the angle of travel relative to the wind or current. Velocity Made Good (VMG) is a crucial concept in sailing and other forms of marine navigation, especially when travelling upwind or downwind. It refers to...

A shore-based system that monitors and manages vessel movements in busy or hazardous waterways to enhance safety, efficiency, and environmental protection.  Vessel Traffic Service (VTS) is an internationally recognised system operated by maritime authorities to regulate and assist vessel movements in congested or high-risk areas such as ports, straits, and busy coastal waters. Using radar,...

The disturbed water left behind a vessel as it moves. This is the turbulent flow directly astern and around the vessel’s track, caused by the hull and propulsion moving through the water. It can affect steering, slow following vessels, and create uncomfortable motion for small craft close behind. It is often confused with wash, which...

A strong rope or line used for mooring, towing, or manoeuvring a vessel, particularly in situations requiring precise control.  Warping is a traditional and essential technique in maritime operations, particularly useful in harbours, narrow waterways, or when precise vessel positioning is required. The verb "to warp" refers to the act of moving a vessel by...

The waves created by a vessel as it moves through the water. This can spread away from the hull and affect other boats, pontoons, moorings, paddle craft and people near the water’s edge. It is different from wake, which is the disturbed water directly behind the vessel. Large or steep wash can cause discomfort, damage...

Removable boards or panels used to close off the companionway of a boat to prevent water from entering the cabin. Wash boards are an essential feature on many boats, particularly sailboats, where they serve as a barrier to protect the interior of the vessel from water ingress, especially in rough seas or heavy weather. Typically,...

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.