A 2¼ square film negative. The Type 12 frigate Yarmouth (1959) in No. 2 dry dock in Rosyth Dockyard. A close view of the port side of the lowered main transducer panel of Hull Outfit 20 Type 174 sonar between 15 and 19 stations. All 60 of the rectangular block components of the transducer are marked with letters, frequencies and numbers. A white line has been painted on the hull. The photographer is on the floor of the dock looking to starboard and slightly aft..