Until about 1886, lightvessels were of wood construction. Later they were chiefly composite, followed by iron, and after 1936 the new builds were all of steel.
The vessels ranged in size from 84’ to 137’ overall length and from 20’ to 26’ in width. The last Trinity House lightvessel was built in 1967.
Moving on from crude elevated ship’s lanterns, the navigation light in older vessels consisted of a grouping of oil wick burners focussed in silvered copper reflectors mounted on a frame, and rotated by a weight-driven clock.
By rearranging the reflector groupings, angling the reflectors and changing the speed of rotation, different light characters could be achieved, a very important identification measure at night in areas with several lights.
The Royal Victoria Docks light vessel of Trinity House, Lightship 93 was built in 1938 and is berthed next to the SS Robin.