Floating Aids

Lightvessels are not self-propelled and have to be towed to and from station. The vessels are predominantly painted red, so that they are conspicuous in daylight. Prior to automation Lightvessels were manned by a crew of 10, with 5 on station at any one time. Today Lightvessels, like Lighthouses are monitored and controlled from the Trinity House Central Planning Unit in Harwich.


Trinity House typically deploys two classes of buoy design. The larger Class 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

IALA Buoyage System

Buoys provided by Trinity House conform to the IALA Buoyage System A which was introduced in 1977. The system consists of lateral, cardinal and other buoys, such as isolated danger and safe water marks. Buoys can be distinguished from each other by
  • the colour of their light and flashing sequence
  • the colour and combination of colours on the buoy
  • the shape of the topmark
This marking scheme is designed to enable mariners to identify a buoy if the light is extinguished and /or the topmark is missing.

Lateral buoys mark well defined channels and indicate port and starboard hand sides of the route to be followed, for port hand marks the buoy and light are coloured red, for starboard marks these are green.

Cardinal buoys are used in conjunction with a compass to indicate where a mariner may find the best navigable waters. They are coloured yellow and black and have white flashing lights.

View IALA leaflets

IALA Buoyage System A leaflet >>

IALA Buoyage System: Points to Remember leaflet >>