A veteran ocean paddler who was stranded 11km off shore after being swept away in turbulent waters has been rescued after being spotted by a Australian Navy submarine.

Ken Dinham was participating in a paddling race from Rottenest Island to Sorrento Surf Life Saving club in Perth when he was swept off his ski.

The force of the swell was so strong the 71-year-old’s leg leash snapped and he watched on as his ski drifted out of reach.

"I couldn't swim fast enough," Mr Dinham told surfski.info yesterday afternoon.

"So I pulled a flare out of my life jacket, flipped the pocket off, pulled the string but absolutely nothing happened.

"I thought to myself, I’m in trouble here because I'm quite far off shore.

Ken Dinham still "can't believe his luck" that the Australian Navy spotted him. (Facebook)

"Being found was a worry for me."

But Mr Dinham’s luck quickly changed when he looked out and spotted the conning tower of an Australian Navy submarine not far from him.

"I still had my paddle so I started waving it in that direction in the hope of attracting attention.

“Before I knew it, the submarine had turned around and was coming towards me.

"I couldn't believe my luck."

The Australian Navy submarine spotted the 71-year-old stranded in the waters. (File)

The Australian Navy contacted rescue teams who then sent a team out to save Mr Dinham.

He was plucked from the water and wrapped in a thermal blanket.

"I'm very grateful to the Australian Navy," he said.