Glossary Archive

A maritime organisation responsible for maintaining navigational aids, including lighthouses and buoys, along England, Wales, and the Channel Islands coasts. It also covers navigational aids in Gibraltar. The British organisation is dedicated to ensuring the safety of shipping and seafarers' welfare. Officially known as the Corporation of Trinity House, it was established by Royal Charter...

A tropical hurricane is an intense tropical cyclone characterised by strong winds, heavy rainfall, and low pressure. These storms typically form over warm ocean waters near the equator and can cause significant damage to coastal areas when they make landfall. Tropical hurricanes are classified based on wind speeds, with categories ranging from 1 (weakest) to...

The direction along the Earth's surface that points directly towards the geographic North Pole. True North, also known as geographic north, is the fixed point on the Earth's surface that aligns with the axis of the planet's rotation. Unlike Magnetic North, which is influenced by the Earth's magnetic field and can shift over time, True...

The wind experienced independently of a vessel’s own movement. This is the actual movement of air over the water, as distinct from apparent wind, which is what the crew feel on board when the vessel is moving. The faster the vessel travels, the more apparent wind shifts forward and changes strength. Understanding the difference helps...

A small triangular sail hoisted at the masthead to help stabilise a boat in heavy winds.  A trysail is a small triangular sail that is hoisted at the masthead of a boat to help stabilise the vessel in heavy winds. It is typically used as a storm sail when the wind is too strong for...

A navigation system designed to organise the flow of vessel traffic in congested or high-risk areas, ensuring safe passage by separating opposing traffic streams. A Traffic Separation Scheme (TSS) is a regulatory measure established by the International Maritime Organization (IMO) to enhance maritime safety in areas where vessel traffic is dense or where there is...

Estimated time remaining to a waypoint giving an indication of arrival time

When a rope passes around an object, such as a post, when tying a knot.

Sea area of the Met Office Shipping Forecast. Covers the southwestern North Sea, off the River Tyne estuary in northeast England. From the River Tyne estuary (Brythonic origin), Tyne typically has moderate northwesterlies of Force 3–5 and slight seas, with stronger winds in autumn and winter. A North Sea surge in January 1953 caused high...

A region of the Earth where the same standard time is used. A time zone is a geographical area that observes a uniform standard time for legal, commercial, and social purposes. The Earth is divided into 24 primary time zones, each generally corresponding to 15 degrees of longitude, reflecting the Earth's rotation and the division...