Glossary Archive

Used in satellite navigation and geolocation to provide the likely accuracy of a satellite-derived position. The DOP concept is essential to understanding the accuracy and reliability of the Global Positioning System (GPS) and other satellite-based navigation systems. Types of DOP There are several types of DOP, each representing different aspects of the positioning precision: PDOP...

To put out extra mooring lines when a storm is expected

To lower a sail; To extinguish a light quickly

Sea area of the Met Office Shipping Forecast. Spans the English Channel at the Strait of Dover between England and France. Named after the port of Dover (Brythonic “Dubris,” waters), Dover experiences southwest winds of Force 4–6 and moderate to rough seas, with frequent coastal fog. The 1989 “White Cliffs Gale” produced gusts over 45...

A downhaul is a line or tackle to apply downward tension on a sail or spar to control its shape and optimise performance. The downhaul is an essential control line on many sailboats, particularly for adjusting the tension on the luff of a sail. By pulling the sail down toward the boom or deck, the...

The direction towards which the stream flows

Refers to the direction in which the wind is blowing relative to a specific point of reference. When sailing or navigating on the water, travelling downwind means moving in the same direction as the wind, which can affect a vessel's speed, manoeuvrability, and tactics.

A navigational method used to estimate a vessel's current position based on a previously known position, factoring in speed, time, and course without using celestial or satellite navigation. Dead reckoning is a fundamental technique in marine navigation that allows sailors to determine their position at sea when more advanced methods, such as GPS or celestial...

The anchor drags when it fails to hold and slides over the seabed

The vertical distance between the waterline and the lowest point of the hull, typically the keel, indicating how deep the vessel sits in the water. The draught (also spelled "draft" in American English) is a measurement in the design, operation, and navigation of boats and ships. It represents the depth of water a vessel requires...