Glossary Archive

World Sailing, formerly known as the International Sailing Federation (ISAF), is the governing body for the sport of sailing worldwide. Headquartered in London, World Sailing plays a pivotal role in promoting and regulating sailing on a global scale. Sailing, a sport that combines the thrill of competition with the beauty of nature, has a rich...

A light where the duration of light and darkness are equal. Isophase describes a navigational aid that emits a light signal with equal periods of light and darkness. This results in the light appearing on for the same time as it is off, creating a distinctive flashing pattern that helps mariners identify the aid and...

On a synoptic chart, a line joining points of equal pressure

Buoy or pillar positioned on a dangerous underwater obstruction. An isolated danger mark is a navigation aid used at sea to indicate a single, isolated danger (like a rock or a wreck) with safe water around it. It’s a marker to help sailors avoid obstacles that might otherwise be hard to spot. Isolated danger marks...

A light where the duration of light and darkness are equal. Isophase describes a navigational aid that emits a light signal with equal periods of light and darkness. This results in the light appearing on for the same time as it is off, creating a distinctive flashing pattern that helps mariners identify the aid and...

A specialised agency of the United Nations responsible for coordinating global telecommunication operations and services, including radio frequency allocation and satellite orbits. The International Telecommunication Union (ITU) is critical in global communications, particularly in the maritime sector. Established in 1865, the ITU is one of the oldest international organisations and has evolved to address the...

A length of webbing (or on rare occasions a length of wire) which run from the bow to the stern of the vessel. They have sufficient slack in them so that you can clip your lifeline to it while still in the safety of the cockpit. You are then able to leave the cockpit safe...

The International Maritime Signal Flag Juliett. Meaning I am on fire and have dangerous cargo on board: keep well clear of me.ORI am leaking dangerous cargo.

A triangular sail set ahead of the foremast, typically attached to a stay, and used to improve a vessel's manoeuvrability and balance. The jib is an essential sail on many sailing vessels, located forward of the mainmast and typically attached to a stay running from the bow or bowsprit to the top of the foremast....

Lines attached to clew of headsail to control sail shape.