Knocked overboard in rough seas off New Zealand, a German yachtsman has credited his jeans with saving his life after he managed to fashion them into a makeshift life jacket that kept him afloat for more than three hours before he was rescued.

Key points: Arne Murke was knocked into the water when his yacht's boom swung unexpectedly

Arne Murke was knocked into the water when his yacht's boom swung unexpectedly He tied knots in his trouser legs and filled them with air, forming a makeshift life jacket

He tied knots in his trouser legs and filled them with air, forming a makeshift life jacket Mr Murke and his brother were tourists in New Zealand and sailing the boat to Brazil

Arne Murke, 30, was sailing with his brother in Tolaga Bay on the east coast of New Zealand's north island last week when the yacht's boom swung unexpectedly, knocking him into the water.

Unable to reach the life jacket thrown by his brother, Mr Murke was soon carried off by the swell.

"Luckily, I knew the trick with the jeans," Mr Murke told the New Zealand Herald.

"Without the jeans I wouldn't be here today. They were really the thing that saved me."

He made knots at the end of the legs and pulled them over the water to get air inside, before forcing them under to trap in the air and create an improvised life vest.

A rescue helicopter managed to locate the German more than three hours after he was knocked overboard.

"It was fortunate the yacht had both a VHF radio and emergency beacons to raise the alert," Rescue Coordination Centre NZ's Chris Henshaw said in a statement on the agency's website.

"Without appropriate communications devices and beacons it may have turned out differently."

The newspaper said the brothers, who had been tourists in New Zealand, had taken a commission to deliver the yacht to Brazil.

Reuters