HMAS Platypus (1917)

At the conclusion of the war, the ship was transferred to the Royal Australian Navy and was commissioned into the RAN on 25 March 1919.

Platypus's main role was to support the RAN's six J-class submarines, which she sailed with from Britain to Sydney between April and July 1919.

Platypus and all six J-class submarines were based at Geelong in February 1920. Due to the poor condition of the submarines and financial pressure on the RAN the Royal Australian Navy Submarine Service was disbanded in May 1922 and Platypus was redesignated as a destroyer tender. Platypus reverted to her original role as a submarine tender in 1929 when the RAN acquired two O-class submarines but was used as a depot ship after these submarines were placed into reserve in 1930. She was renamed HMAS Penguin on 15 August 1930.

In October 1932, a mutiny occurred aboard Penguin.[1] The mutiny was in protest of the decreases in sailor pay and conditions: Depression-era cutbacks had impacted them harder than officers, as they had no avenues of protest.[1] The ship's commanding officer was sympathetic, promising that he would forward their concerns to the Australian Commonwealth Naval Board (which refused to consider them) and that they would not be punished.[1]

She continued as a depot ship until 26 February 1941 when she was renamed HMAS Platypus and returned to seagoing service as a training ship. In May 1941, Platypus sailed to Darwin to serve as a base ship. She survived the Japanese attack on Darwin in February 1942 and remained at Darwin until January 1943 when she sailed to Cairns, Queensland where she again served as a base ship until May 1944. In June 1944 Platypus received a major refit and sailed to New Guinea as a repair and maintenance vessel. She operated off New Guinea and Morotai Island until returning to Australia in December 1945. The wartime service of Platypus was later recognised with the battle honour "Darwin 1942–43".[2][3]