in that column. If the last ship in column was hit, the rescue task fell to the escorting warships. In practice, the escorting warships performed rescue tasks more often than the 25% suggested by random hits on a four-ship column because some merchant ships refused to leave the protection of the convoy formation to fall back and remain a stationary target while rescuing survivors. Furthermore, merchant ships were not well suited to manoeuvre to pick up survivors, and those attempting rescue were hampered by lack of suitable rescue equipment. For the role the Admiralty sought out small, quick, manoeuvrable vessels; it drew many from among the Clyde Shipping Company's coastal passenger transports. The requisitioned passenger ships had a speed of 11 to 12 knots, which enabled them, after completing their rescue operations, to catch up with the convoys travelling at 10 knots. Although these vessels had not been built for the Atlantic or the Arctic, none was lost to Atlantic storms; one did ice-up and founder off the coast of Newfoundland. The rescue ships were not hospital ships and so were legitimate targets as far as German submarines or bombers were concerned. Consequently, the Admiralty armed them with AA guns for protection when they were separated from the convoy and vulnerable to enemy attack. In addition to equipment for rescuing and treating survivors, rescue ships carried High Frequency radio Direction Finding equipment (abbreviated to HF/DF and known as "Huff-Duff") to assist in the location of U-boats. The rescue ship's position at the rear of the convoy provided good triangulation in combination with the HF/DF installed on the escort leader typically patrolling in front of the convoy. The Rescue Ship Service was organised by Lieutenant-Commander L. F. Martyn RNVR, who later co-authored a book highlighting the successes and challenges of the rescue ships. List of convoy rescue ships The rescue ships were: Aboyne 1020 tons GRT, built 1937, in rescue service from 11 June 1943, sailed with 26 convoys, rescued 20 survivors. Accrington 1678 tons, built 1910, in rescue service from 26 July 1942, sailed with 36 convoys, rescued 141 survivors. Beachy 1600 tons, built 1936, in rescue service from January 1941, sailed with 5 convoys, sunk by aircraft 11 January 1941 while assigned to convoy HG-49. Bury 1686 tons, built 1911, in rescue service from 27 December 1941, sailed with 48 convoys, rescued 237 survivors. Copeland 1526 tons, built 1923,