A sheet film negative, possibly acetate. The submarine Sealion (1959) undergoing a refit in Admiralty floating dock AFD60 (1966) at Faslane. A close view of the starboard propeller, A bracket and shaft taken from the floor of the dock looking up. Above the propeller is the aft hydroplane and the stabilising fin. An Admiralty copy negative of a whole plate photographic print. A vertical format negative.