Sailor Andrew 'Bart' Simpson was trapped underneath the boat and, despite attempts by doctors afloat and subsequently ashore, he was unable to be saved.
He was trapped under the platform for an estimated 10 minutes.
Simpson represented Great Britain at two Olympic Games, sailing in the Star class alongside Iain Percy.
The pair took gold at the Beijing 2008 Games and last year were close to topping the podium once more, only to be bumped down to silver in the medal race.
Before last summer's Olympics, Simpson admitted that winning the America's Cup was his biggest goal.
He had hoped that dream would come true as strategist for challenger Artemis Racing, whose sailing team director and tactician is close friend Percy.
More top news
Donald Trump has reconfirmed his nation's commitment to securing peace in Afghanistan
Yvette Cooper has called on Twitter to 'get its act together', urging a crack down on hate speech.
An earthquake has hit the Italian resort island of Ischia, killing at least one person and trapping around six others.