An Australian fisherman has hung onto his father's body, a portable cooler and an emergency beacon after a wave capsized their boat off Brisbane, Australian authorities have said on Monday.

The fisherman, his late father and another man had been in the water, 10-20 nautical miles off Cape Morton, for almost two-hours before they were rescued on Sunday morning.

Authorities believed the father had succumbed to the elements about half an hour before rescue, Fairfax Media reported on Monday.

Rescuers say the two survivors -- 24 and 30 years old respectively -- could have also died if it had not been for the emergency beacon (EPIRB) on their five-to-six meter boat, which had only been bought on Saturday.

An emergency helicopter was dispatched after the emergency beacon was activated. The men would have died if it had not been for the EPIRB, authorities said.

The men had gone out on an overnight fishing trip on Saturday but ran into trouble while trying to reposition their boat on Sunday morning.

Authorities said a wave had swamped the motor, shortly followed by another that broke and capsized the boat, putting the fishermen in the water.

It is believed the fishermen were not wearing life-jackets, despite attempts to put them on and salvage any floatation devices before the boat sank.