When Wednesday afternoon's violent storm in Ottawa finally subsided and residents emerged to inspect the damage caused by the lashing rain and howling winds, Andrew Furey turned his eyes to the water.

That's when Furey, the harbour manager at Britannia Yacht Club, noticed people waving for help from the middle of the Ottawa River.

Their sailboat had been caught in what Furey described as the "eye of the storm," and had sunk.

Furey jumped into a rescue dinghy and raced out to help. About two kilometres off shore he found three men in their 50s bobbing in the water, clinging to the mast of their vessel — the only part of the boat still above water.

The men appeared to be experienced sailors and stayed calm throughout the ordeal, Furey said.

"They were in pretty good spirits," he said.

Furey said the men told him they planned to return to retrieve their boat.

Only the tip of the boat's mast and sail protruded from the water Thursday morning. (Giacomo Panico/CBC News)

Once the boaters were safely ashore, Furey took time to survey the storm damage to the harbour. He estimates 200 of the 250 boats moored there were damaged to some extent.

According to the Britannia Yacht Club, wind speeds reached 160 km/h at the storm's peak.

Furey said of all the storms he's witnessed, only Hurricane Igor, which struck Newfoundland in 2010, was worse than the one he saw Wednesday.

Andrew Furey estimates 200 of the 250 boats in the harbour were damaged in the storm. (Chris Klotz/Supplied) "This was unprecedented, it was out of nowhere."

Meanwhile, the cleanup continues elsewhere in the city.

Thousands of residents were without power after the storm felled trees and ripped roofs from buildings.

Some said it felt like a tornado, but Environment Canada hasn't confirmed anything beyond strong winds.

"When those downdrafts become particularly severe, they can hit the ground and spread out and do damage that to many people, to the public, often resembles tornadoes," Environment Canada meteorologist Peter Kimbell said Wednesday.