An Australian surfer who helped rescue a South African man after he was lost in Indonesian waters for 27 hours has told of the moment he and eight mates spotted the man, still alive, bobbing in the ocean.

When Perth lawyer Colin Chenu and his mates saw ''a red head and a white arm waving'' - 19kilometres from the Mentawai Islands, off the west coast of Sumatra - they threw a lifebuoy into the water and jumped over the side of their Sydney-owned charter boat and swam to the stricken man, who was dehydrated and suffering a gash from a seagull attack. He had also been circled by a shark and stung by jellyfish.

Saved: Brett Archibald climbs aboard the rescue yacht. Credit:Jeff Vidler

Embracing his rescuers, the South African man, whose wife had been told he was dead, said: ''I love you Aussies, I'm never going to bag you guys ever again.''

Mr Chenu, 49, said: ''It was a feeling of sheer elation, when we dragged him onto the boat, we were all pumping the air, screaming.