Glossary Archive

Measurement of the geometric strength of satellite configuration in a Global Navigation Satellite System (GNSS) receiver. It quantifies the effect of satellite geometry on the accuracy of the position calculation. A lower PDOP value indicates better satellite geometry and results in more accurate position fixes. PDOP is calculated based on the positions of the satellites...

The RYA Powerboat Advanced course is designed for experienced powerboaters operating in challenging conditions, including night navigation. Participants learn advanced passage planning, navigation, and high-speed handling in adverse weather. The course emphasizes safety, decision-making, and the use of radar and electronic aids. By the end, participants will have the confidence to operate powerboats independently in...

The RYA Powerboat Intermediate course bridges the gap between Level 2 and advanced powerboating. Participants learn navigation, passage planning, and handling powerboats in moderate conditions. The course includes practical exercises on anchoring, docking, and responding to emergencies. This program is ideal for those seeking to improve their skills and prepare for more challenging boating environments...

The official permission granted to a vessel by port health authorities, allowing it to enter a port and conduct operations after confirming it is free from contagious diseases or other health risks. Pratique is a term deeply rooted in maritime operations, particularly concerning the health and safety protocols of ports and harbours. Historically, it emerged...

Any form of water, such as rain, snow, sleet, or hail, that falls from the atmosphere and reaches the Earth's surface. Precipitation is a key component of the Earth's water cycle and plays a crucial role in marine and coastal environments. It occurs when water vapour in the atmosphere condenses into water droplets or ice...

The act of compelling or requisitioning a vessel, crew, or equipment for immediate use, often in urgent or unforeseen circumstances. The phrase "pressed into service" originates from maritime practices, particularly during times of war or emergency, when ships, sailors, or resources were forcibly commandeered by Press Gangs. Historically, this was most notably associated with the...

Groups authorised by naval authorities to forcibly recruit men into naval service, often through coercion or outright abduction. Press gangs were not subtle. They did not send polite invitations, nor did they wait for volunteers. If you were a reasonably fit man near a British port in the 17th to early 19th centuries, you were,...

The wind direction most commonly experienced in a particular area over time. This is based on local weather patterns and seasonal tendencies rather than the wind on a single day. Around the UK, south-westerly winds are common in many coastal areas, although local effects can change what is experienced on the water. Knowing the usual...

A line or tackle rigged to the boom or spar to prevent unwanted movement, particularly to stop a boom from swinging dangerously during an accidental gybe. A preventer is an essential safety feature in sailing, designed to stabilise the boom and reduce the risk of injury or damage during certain manoeuvres or in challenging conditions....

The zero-degree longitude line that is the starting point for measuring longitude and dividing the Earth into the Eastern and Western Hemispheres. The Prime Meridian is an essential global navigation and cartography reference line, particularly for marine navigation. It runs from the North Pole to the South Pole, passing through the Royal Observatory in Greenwich,...