A man who spent all night drifting on a busted jet ski has SpongeBob SquarePants to thank for his survival.

Eric Bettanin, 29, bought his bright yellow SpongeBob SquarePants board shorts as a joke, but now he could not be more proud of them.

Stranded at sea after his jet ski broke down, Eric used the brightly coloured pants to attract attention as he drifted off notorious Port Phillip Heads at dawn yesterday, the Geelong Advertiser reports.

Mr Bettanin, of Shepparton, said he placed them on his head to keep himself warm and flag down a passing rescue boat.

"As silly as it sounds they made quite a significant difference to my core temperature," he told the newspaper.

"When I stood up and started waving I had them on my head."

Police began searching for Mr Bettanin at around 9.30pm on Monday after friends lost sight of him at Torquay when his jet ski developed mechanical problems.

He spent nine hours stranded at sea before he was finally rescued 10 nautical miles away at Point Lonsdale early yesterday morning.

Senior Constable Rob Help from the water police said the man was extremely lucky to survive because he was not equipped for the conditions.

He was taken to Geelong Hospital suffering from mild hypothermia.