Several people escaped serious injury when a pontoon at the Port Bouvard marina near Mandurah was dragged about 800m.
David Constanine says he is now homeless after the yacht he had lived on in the marina sunk after the jetty snapped from its anchorage and ran aground.
"I was on the boat when it happened," Mr Constanine said. "The wind gusts were incredible. There was 50 knot winds and there was nothing I could do, I knew it the boat was going to hit land."
Mr Constanine said he jumped ashore to save himself when the boat slammed into the rocky shoreline.
"I was worried the mast was going to come down and knock me out."
He said he was numb when he looked at his boat as it sank.
"I lived on it for 10 years," he said. "It's an example of maritime history destroyed."
He said the 13-metre 58-year-old vessel was worth about $100,000 and was "irreplaceable".
Thousands of dollars worth of personal property was destroyed, including navigational equipment, books and photos.