Have you ordered your father's Navy Service Records? Get his medical too as he might have been sent to Australia for care. The records will have the ships or duty sations he served. There were 2 Astoria's in WWII, one commissioned in 1930 and sunk 1942 and one commissioned 1944-CL 90 This one was in the Battle of the Coral Sea, but the history I read never mentions going or being in Australia. Could be the woman was an Australian citizen stationed/living in a place your father had liberty or duty. Goggle "Australian champion swimmers" and see what you can find. Post to an Australian message board.