On 22 January 1963, with the Royal Navy intending to withdraw its Fourth Submarine Squadron from its base in Sydney, the Minister for the Navy, Senator John Gorton, announced Cabinet approval for the purchase of 8 Oberon Class submarines for the RAN, though the order was later reduced to 6. Although the first of the new submarines, HMAS Oxley (II), would not commission until March 1967, consideration necessarily turned to where the submarines might be based.
Since the Second World War HMAS Penguin at Balmoral in Sydney had been used by the submarines of the Fourth Submarine Squadron but it was deemed unsuitable as a permanent establishment due to its exposed position. Neutral Bay, further inside Sydney Harbour, had, for many years, been used as a protected anchorage when weather conditions proved unsuitable at Penguin, and it was also home to the existing RAN torpedo maintenance facility. The availability of land close to an existing site, on a bay well protected from the weather, made it an ideal location for a naval establishment and in November 1964 an announcement was made that Neutral Bay had been selected as the preferred site for the RAN’s new submarine base.
The new facility was formally named HMAS Platypus in a commissioning ceremony held on 18 August 1967. The selection of the name Platypus perpetuated a long association between the on-again-off-again RAN submarine service and 2 previous submarine tenders named Platypus which had sustained the former J Class submarines based at Corio Bay, Geelong, during the 1920s.
Over the next 32 years, 9 submarines operated from Platypus, 6 Australian Oberon class: Oxley (II), Otway (II), Ovens, Onslow, Orion and Otama, as well as HM Submarines Trump, Tabard and Odin.
On the occasion of the 25th anniversary of its commissioning Platypus and the Australian Submarine Squadron were granted the right of Freedom of Entry by the Municipality of North Sydney. Special commemorations were held during ‘submarine week’ which took place in Sydney between 23-29 November.
In 1994 the headquarters of the Commander Australian Submarine Squadron (COMAUSUBRON) was relocated to HMAS Stirling. This foreshadowed the introduction into service of the new Collins Class submarines and a strategic decision to relocate the RAN submarine squadron to Fleet Base West, Garden Island, WA in support of a ‘two ocean’ navy basing policy.
On 29 March 1999, Platypus bid farewell to the last of the operational Oberon class submarines. Onslow decommissioned on that day at Platypus while Otama departed Sydney for the last time on its way to its new home port in Western Australia.