A roll film negative. On board the Tribal class type 81 frigate Mohawk (1962) in Portsmouth Dockyard. She was in a dry dock from 21 March to 11 April 1972 when she moved to the South Railway Jetty. In the hull outfit 18 sonar (type 177) compartment between 32 and 37 stations on 4 deck, looking up and slightly forward from aft showing the top of the hoisting shaft. A vertical format negative.