A quick-thinking German tourist says he owes his life to his jeans and a good memory after recalling a military survival technique that kept him alive for three hours in rough seas off New Zealand.

Arne Murke, who had set out with his brother to sail a 12-metre yacht from Auckland to Brazil, was knocked overboard while dressed only in a T-shirt and jeans on March 6.

Arne Murke’s inflated jeans kept him afloat until help arrived. Photo: ELP

His brother raised the alarm after he couldn’t reach him in the three-metre swell and attempts to throw the 30-year-old a life jacket failed.

“Luckily, I knew the trick with the jeans. Without the jeans I wouldn’t be here today, they were really the thing that saved me,” he told New Zealand’s Sunday Herald.

He transformed his jeans into a life-saving buoyancy aide using a technique employed by Navy Seals.

“I took a deep breath, took out my jeans, made knots at the end of the legs and inflated the jeans – pull it over water and get air inside and then push it under water,” he said.

“I had like an improvised life vest.”

After about three-and-a-half hours in the water, Murke was spotted by a rescue helicopter.

“Life jackets are essential for all recreational activities on the water,” Chris Henshaw from the Rescue Coordination Centre NZ said in a statement.

“It was fortunate the yacht had both a VHF radio and emergency beacons to raise the alert,” he added.

“Without appropriate communications devices and beacons it may have turned out differently,” Henshaw said.

-with AAP