The America's Cup catamaran that capsized in San Francisco Bay, killing an Olympic gold medalist, nosedived during a difficult maneuver and broke into many pieces, an official said Friday.
The Artemis was conducting a maneuver that required it to change direction when it capsized on Thursday, America's Cup Regatta Director Iain Murray said.
The boat was practicing with the Oracle team.
''Artemis and Oracle were out there training in what they had been doing for months,'' Murray said. ''And looking frankly quite good.''
Murray said the maneuver involved changing direction and wind flow across the boat. Though difficult, it was normal, he said.
Coast Guard Lt. Jeannie Crump has said Coast Guard officials weren't sure what caused the boat to capsize. San Francisco police said they will lead the investigation.
Andrew ''Bart'' Simpson, 36, was submerged underwater for more than 10 minutes when the vessel capsized. Efforts to revive him were unsuccessful, and he was pronounced dead a short time later.
Murray said Simpson was on a trampoline on the windward side of the yacht with crew members and got trapped under some of the solid sections of the yacht, out of site to those on board who were looking for him.
''How he got to where he got to we do not know,'' Murray said.
Simpson had collected an Olympic gold medal in sailing in 2008 and a silver medal at last year's games when Artemis Racing came calling with a chance to win yachting's top prize - the America's Cup.
''Moving the family to San Fran for 6 months is pretty hectic!!!,'' Simpson tweeted in March. ''The cup should be fun though!!''
As the strategist for the Swedish team, he was involved in all decision-making on the boat and participated in trimming the sails.
''The entire Artemis team is devastated by what happened,'' CEO Paul Cayard said in a statement on the team's website. ''Our heartfelt condolences are with Andrew's wife and family.''
Cayard didn't take questions during a brief news conference Thursday evening and didn't return telephone calls.
The British Olympic Association described Simpson as a ''treasured and accomplished member'' of its teams.
''Andrew Simpson was a hugely accomplished sailor and Olympian,'' International Olympic Committee President Jacques Rogge, a former Olympic sailor from Belgium, said in a statement to The Associated Press. ''He died pursuing his sporting passion.''
British newspapers reported that Simpson is survived by a wife and an infant child.
Artemis Racing said doctors ''afloat'' with the team and on shore were unable to revive Simpson after he was freed from the wreckage. Another sailor suffered minor injuries, and the rest of the crew of about 11 people was accounted for and taken back to their dock in Alameda.
Officials said winds were blowing between 15 and 20 knots (17 to 23 mph) when the boat capsized. The National Weather Service later issued a small-craft advisory, warning inexperienced mariners to stay off the bay and indicating winds of between 21 knots and 33 knots.
Simpson and the unidentified injured sailor were brought to shore at the St. Francis Yacht Club in San Francisco, where paramedics performed CPR on Simpson.
It was the second time a sailor has died during training for the America's Cup. In 1999, Martin Wizner of the Spanish Challenge died almost instantly when he was hit in the head by a broken piece of equipment.
No deaths have been recorded during the actual racing since its inception in 1851.
Simpson and his partner Iain Percy won an Olympic gold medal for England in 2008 in the Star class of sailing. The duo was expected to repeat in London in 2012 but was upset by a Swedish team and settled for silver.
Artemis Racing has had its share of upheaval in the buildup to the 34th America's Cup. Late last year, skipper Terry Huthinson of Annapolis, Md., was released. He was replaced by Nathan Outteridge of Australia, who won a gold medal at the London Olympics.
The team has had technical problems, as well. Last fall, Artemis said the front beam of its AC72 catamaran was damaged during structural tests, delaying the boat's christening. A year ago, Artemis' AC72 wing sail sustained serious damage while it was being tested on a modified trimaran in Valencia, Spain.
The Artemis wasn't the first America's Cup boat to capsize on the wind-swept San Francisco Bay. Oracle's $10 million boat capsized in 25-knot winds in October, and strong tides swept it four miles past the Golden Gate Bridge.
No one was injured, but the rough waters destroyed the 131-foot wing sail.
Stephen Barclay, CEO of the America's Cup Event Authority, said officials were investigating Thursday's accident. He said it was unclear what effect the death will have on the America' Cup races, which are scheduled to run from July to September.
It was too soon to answer questions about the safety of the high-tech boats on the San Francisco Bay, Barclay said.
''Obviously a catamaran is more prone to capsizing than a mono-hull,'' he said. ''Whether boats are safe or unsafe, we're not going to speculate on those things.''
In addition to sailors wearing crash helmets and life vests, chase boats carry doctors and divers, Barclay said.
''There are lots of precautions that are taken, and some of those are as a result of Oracle's mishap last year,'' he said.
The catamarans have proved hard to handle. The wing sail looks and acts like an airplane wing, improving the yacht's speed and maneuverability. The 7-ton boat's hulls are lifted out of the water and it skims along the waves on ''foils,'' reducing the drag on the boat and increasing speed dramatically.
