HMAS "Platypus" was a submarine depot ship and base ship operated by the Royal Australian Navy (RAN), ordered prior to World War I to support the Australian submarines originally known as just AE1, HMAS "AE1, was an "E"-class submarine of which organization?
HMAS Platypus (1917):  Ordered prior to World War I to support the Australian submarines "AE1" and "AE2", "Platypus" was not completed until after both submarines had been lost, and she was commissioned into the Royal Navy from 1917 to 1919.
i don't know