Terrified Cambridge rowers Tara Remington and Iain Rudkin feared for their lives as they sat in their tiny 7m boat in the middle of the Atlantic Ocean yesterday morning during a prolonged shark attack.

The pair were about 600 nautical miles into the 2935-nautical-mile transatlantic race from the Canary Islands to Antigua when the onslaught began.

The team's shore manager, Rob Hamill, said they were anchored at the time because strong head winds had made it impossible to row.

"They saw the shark go under the boat, it circled a couple of times then just went for it," said Hamill.

"It wasn't just a one-off attack. It kept launching into it."

Remington and Rudkin dived into the cabin, tried to remain as quiet and still as possible and sat out the attack, which ended after 15 minutes.

"It was so aggressive and persistent, for a while we wondered if it would ever stop. It just kept hitting the boat, having a go at the rudder, the sea anchor and hull," Remington wrote on the team's website

"We weren't sure it wasn't biting holes in the underside so we rang the support ship Aurora for advice and possible assistance."

Hamill said the pair estimated the shark was about 3m to 3.5m long.

"The boat is 6ft [1.8m] wide and they could see it out either side as it went under the boat.

"Iain said, kind of jokingly, that he was considering taping the gas canister to a flare and doing a Jaws [reference to a scene in the Jaws movie when a gas canister was used to blow up a shark].

"If the attack had carried on for too much longer they would seriously have had to have thought about doing something."

The support vessel arrived six hours later and planned to remain alongside Remington and Rudkin until morning to check the race boat for damage.

"The scary thing is I was in the water cleaning the hull for barnacles at exactly the same time [on Monday] and Iain did likewise the day before," Remington said.

"I haven't bitten my nails for over a year now, but in that time I chewed two nails right off."

Hamill, who has won the race three times, said he had never heard of such an attack happening before.

The boats were designed to self-right, so if the craft had flipped during the attack, Remington and Rudkin would have been safe in the cabin.

However, if the shark had smashed through the hull, causing the craft to sink, it would have been a different story.

Remington and Rudkin, who make up Team Sun Latte, are among 26 competitors in the race.

They are 16th overall and second in the mixed-crew fleet.

Hamill said the determined duo, although clearly shaken by the attack, had no plans to quit the race.