An Olympic gold medal winner killed in a sailing accident was "a true gentleman", according to Miss Northern Tiffany Brien, a top yachtswoman who trained alongside him.
America's Cup bosses have promised a full investigation into the accident in which British Olympic gold medal winner Andrew Simpson died.
Mr Simpson (36) was sailing with the Swedish Artemis Racing team in San Francisco Bay when his catamaran capsized on Thursday and he became trapped underneath.
The sailor, affectionately known as "Bart", was one of 11 crew members aboard the 72ft vessel which flipped over at about 12.30pm local time.
He was trapped underwater by the AC72 catamaran's platform for about 10 minutes, his team said, and doctors both in the water and on the shore could not revive him after he was freed.
Tributes from the sailing world and beyond have been paid to the married father-of-two, who won gold at the 2008 Beijing Olympics.
Among those expressing their sorrow was beauty queen Tiffany, from Holywood, Ireland's number one in the Women's Laser Radial class and widely tipped for the Irish Olympic Sailing Team in 2016.
She spent time with Mr Simpson when he took coaching sessions here in 2010.
"He was lovely to me, he always had time to say hello and was friendly," she told the Belfast Telegraph.
"He was a lovely guy, very genuine and a true gentleman.
"It's tragic. Sailing is a such a close-knit community, everyone knows everyone, and it has been a big shock. All my friends throughout the world are talking about it, it has upset a lot of people."
Coleraine rower Peter Chambers, who won silver for Team GB at the London Olympics, said: "It is very tragic news that Andrew lost his life doing what he loved in life." Stephen Barclay, the chief executive officer of the America's Cup Event Authority, said an investigation would address why the accident occurred.
"What we do know is that he was trapped underneath and it was for a few minutes; we're not sure if it was one, two, three or 10.
"These boats are very fast and if these sorts of things happen there are procedures and those sorts of things that we follow."
The accident happened near Treasure Island in San Francisco Bay. Footage showed the yacht's sail lying on the water's surface and one of its two red hulls raised in the air as rescue boats surrounded it.
Mr Simpson was part of the Artemis Racing team that planned to challenge for the 34th America's Cup, and was the team's strategist.
He was sailing alongside childhood friend and Olympic partner Iain Percy, who is Artemis' sailing team director and tactician.
As well as winning gold in Beijing, Mr Simpson won silver in last year's Olympic Games in London alongside Percy.
The Olympian lived in Dorset with his wife Leah and their two young children.
The family had temporarily moved to San Francisco so he could focus on training for the America's Cup.