Trinity House typically deploys two classes of buoy design; the larger Type 1 buoys are over 15 metres high including the tail tube and weigh over 10 tons. They are fitted with a tail tube to help stabilise the buoy in the water and are held on the seabed by cast iron sinkers weighing 3-5 tons.

Buoys can be either lighted or unlighted and many are installed with a fog signal in the form of either bells or automatic whistles.

Cardinal marks

Cardinal Marks are used in conjunction with the compass to indicate the direction from the mark in which the deepest navigable water lies, to draw attention to a bend, junction or fork in a channel, or to mark the end of a shoal

Emergency Wreck Marking buoys

Trinity House has a statutory duty under the Merchant Shipping Act 1995 to mark and, if appropriate, remove wrecks which are a danger to navigation

Isolated danger marks

Isolated Danger Marks are used to mark small, isolated dangers with navigable water around the buoy

Lateral marks

Lateral Marks are used generally to mark the sides of well-defined, navigable channels. They are positioned in accordance with a Conventional Direction of Buoyage

Safe water marks

Safe Water Marks may be used mid-channel, as a centreline or at the point where land is reached. These buoys indicate the presence of safe, navigable water all around the buoy

Special marks

Special Marks are not primarily intended to assist navigation but are used to indicate a special area or feature, the nature of which is apparent by referring to a chart or Notice to Mariners

IALA Maritime Buoyage System

Buoys provided by Trinity House conform to the IALA Maritime Buoyage System A which was introduced in 1977

We maintain and inspect over 10,000 buoys per year around the coast of the UK

Inspecting a buoy aboard THV Patricia

Trinity House maintains around 450 buoys and inspects local aids to navigation maintained by port and harbour authorities, utility companies and oil/gas rig and wind farm operators, totalling around 11,000 aids to navigation.

Watch the video below to see how we operate and maintain buoys as part of our mix of aids to navigation.