Nick Dwyer and Barbara Heftman say they thought they would not survive the ordeal.
Dwyer says their yacht's rudder broke on Saturday on route from New Zealand to Sydney.
Heavy seas capsized the yacht several times before he activated an emergency beacon on Tuesday.
They were delivered by a police boat to Sydney Harbor Wednesday night after abandoning their 12-meter (40-foot) sailing boat in 6-meter (20-foot) seas more than 370 kilometers (230 miles) east of Sydney.