Safety fears were raised months ago over the super-fast yacht in which Olympic gold-medallist Andrew Simpson died, it was revealed last night.
The 36-year-old father of two was killed on Thursday when the catamaran flipped over during a training session off the California coast.
Mr Simpson is believed to have drowned after becoming trapped under the platform of the capsized AC72.
An investigation has begun into claims the boat was a potential death trap. Experts said safety concerns had been raised after another AC72 capsized last year.
Last night, Mr Simpsons distraught father paid tribute to a wonderful son and added: I couldn't be more proud of him and everything he achieved. His wife Leah was believed to be flying back from San Francisco with their two young children.
The sailor, affectionately known as Bart Simpson after the cartoon character, had been training for the Americas Cup. He and ten other crew were sailing with the Swedish team Artemis Racing in San Francisco Bay when the 72ft yacht capsized.
Mr Simpson was trapped underwater for about ten minutes. It is not known whether he was conscious for part of this time. Doctors were unable to revive him. Another crew member suffered minor injuries.
Footage from the scene appears to show the right hull broken off and under the central platform where the crew usually stand.
It is not known whether this was a cause or result of the accident, or how Mr Simpson, the team strategist, became trapped. Last night, Mr Simpsons father said his son would have been wearing an oxygen bag on his back.
Speaking from his home in Windlesham, Surrey, Keith Simpson, 70, said: "I couldn't be more proud of him and everything he achieved. He was a wonderful son and father. "Referring to the accident, he said: "I don't know if he was conscious or not. We don't know. Parts of the boat disintegrated and came crashing down."
Asked if his son had expressed concerns about the AC72, he said: "He did at the beginning, but he was enjoying it. He was just sitting on the wrong place of the boat. The wrong place at the wrong time."
Winds at the time the boat flipped over were a little above normal 25 to 35mph. Inexperienced sailors had been warned to stay off the bay.
A sailing expert described the catamaran which can skim the water at up to 46mph as a potential death trap.
Gael Pawson, editor of Yachts and Yachting magazine, said safety concerns were raised in October when an AC72 sailed by Australian Olympic gold medallist Tom Slingsby and yachtsman James Spithill capsized in San Francisco Bay. They escaped serious injury.
Miss Pawson said: "A number of people said when that crash happened that these are potential death traps and this was an accident waiting to happen."
"These boats lift up as they sail. As soon as something hits, even clipping a wave, it will flip right over. They are sailing boats right on the edge of control and are pushed to the limit."
Americas Cup bosses have promised a full investigation.
Stephen Barclay, head of the Americas Cup Event Authority, said: "These boats are very fast and if these sorts of things happen then there are procedures that we follow. Those procedures were followed."
He added that "sailors would normally wear crash helmets and life vests, and supporting boats would carry doctors and divers."
Mr Simpson, who began sailing when he was four or five, won gold at the 2008 Beijing Olympics and silver in last years London Games as well as a gold in the World Championships in Brazil in 2010. He had moved his family from Sherborne in Dorset to San Francisco to focus on training for the America's Cup.
Paul Cayard, Artemiss chief executive, said the team was devastated. He said: We obviously had a tragic day today. Our thoughts and prayers are with Bart Simpsons family and also with the rest of the team-mates.
- Daily Mail