Volume Eight - Pre-Victorian to the present day - more aspects - A brief history of Trinity House lightvessels . .

A visit to the chain room showed why break-adrifts are rare. The chain of a lightship is made of huge links of wrought iron, one and a half inches in diameter. Each link has been tested to take one hundred tons and each six foot of chain weighs one hundredweight.

The Trinity House Depot of Great Yarmouth on the east coast of Britain supervises a coastal stretch from Dunwich to Berwick and includes in its area nine lightvessels which have to be brought in every three years for overhaul in dry dock.

The tender attached to this depot. T.H.V. Mermaid, carries out the relief of all nine lightvessels and a separate mess room for lightvessel masters, with combined sleeping and feeding accommodation for twenty-one lightsmen. Mermaid is powered by four six-cylinder diesel engines and her overall length is nearly two hundred and twenty-one feet. She is the sister ship to T.H.V. Stella and is equipped with all modern navigational aids.

T.H.V. Mermaid built 1959 by J. Samuel White of Cowes, Isle of Wight and in service with Trinity House as a tender vessel until 1986. [273]