Glossary Archive

A vessel for dredging a channel

To be carried along by currents or wind without a set course or direction. The movement of a vessel or object caused by wind, currents, or tides, often resulting in a deviation from its intended course. Drift is a fundamental concept in maritime navigation, referring to the unintended movement of a vessel due to external...

A device, often resembling a small parachute or cone, deployed from a vessel or lifeboat to create drag and stabilise its movement in rough seas. A drogue is an essential piece of equipment used in maritime operations, particularly in challenging sea conditions. Its primary function is to slow down a vessel or lifeboat by increasing...

The vertical distance between the seabed or a drying feature, such as a rock or sandbank, and chart datum, which is usually lowest astronomical tide. The drying height is a critical concept in marine navigation, particularly in tidal areas, as it indicates the elevation of a feature that becomes exposed during low tide. This measurement...

An automated VHF and MF/HF radio communication system used in maritime environments to send distress alerts, establish contact, and exchange routine messages between vessels and shore stations. Digital Selective Calling (DSC) is a critical component of the Global Maritime Distress and Safety System (GMDSS), designed to enhance safety and efficiency in maritime communications. It operates...

The measured distance, typically in nautical miles, between a vessel's current position and a predetermined navigational point or waypoint. The term "Distance to Waypoint" is a fundamental concept in marine navigation, particularly in the context of electronic navigation systems such as GPS or chartplotters. A waypoint is a specific location marked on a nautical chart...

A high-performance synthetic fibre known for its exceptional strength-to-weight ratio. It is often used in marine applications for rigging, lifelines, and other applications requiring lightweight, strong, and low-stretch materials. Dyneema is highly resistant to abrasion, UV exposure, and moisture, making it a popular choice for sailing and other marine activities.

To let a rope out gradually

The period during which the tide is receding, causing water levels to fall as it flows away from the shore towards the sea. Ebb tide is a fundamental concept in tidal cycles, describing the phase when the sea level decreases after reaching high tide. This occurs due to the gravitational pull of the moon and...

An Electronic Chart Display and Information System (ECDIS) is a geographic information system used for nautical navigation that complies with IMO regulations as an alternative to paper nautical charts. IMO refers to similar systems not meeting the regulations as Electronic Chart Systems (ECSs).