HMS Alliance

HMS Alliance is a Royal Navy A-class, Amphion-class or Acheron-class submarine, laid down towards the end of the Second World War and completed in 1947. The submarine is the only surviving example of the class, having been a memorial and museum ship since 1981.The Amphion-class submarines were designed for use in the Far East, where the size of the Pacific Ocean made long range, high surface speed and relative comfort for the crew important features to allow for much larger patrol areas and longer periods at sea than British submarines operating in the Atlantic or Mediterranean had to contend with. Alliance was one of the seven A-class boats completed with a snort mast - the other boats all had masts fitted by 1949.HistoryFrom 9 October 1947 until 8 November the submarine undertook a lengthy experimental cruise in the Atlantic Ocean off the coast of Africa to investigate the limits of the snort mast, remaining submerged for 30 days.Between 1958 and 1960 Alliance was extensively modernised by having the deck gun and external torpedo tubes removed, the hull streamlined and the fin replaced with a larger (26 feet 6 inch high), more streamlined one constructed of aluminium. The purpose of these modifications was to make the submarine quieter and faster underwater. Following the modifications the wireless transmitting aerial was supported on a frame behind the fin; but was later replaced with a whip aerial on the starboard side of the fin which could be rotated hydraulically to a horizontal position.The original gun access hatch was retained however, allowing Alliance to be equipped with a small calibre deck gun again when serving in the Far East during the Indonesian Confrontation of the earlier 1960s.