Brian Walton, of Usworth, Washington, Tyne and Wear, died after being washed overboard from the 38ft yacht Mephisto. He was one of two crewmen swept away while changing the spinnaker. The other managed to cling to the sail, according to Sue Hardwicke, a Cowes spokeswoman.
A 30-year-old woman sailor, understood to come from Shaftesbury, Dorset, was hit by a boom aboard the 30ft yacht Valdemar and died in a helicopter before reaching Southampton general hospital, coastguards reported.
Three other yachtsmen were injured in the race, which attracted more than 600 competitors, and another suffered a suspected heart attack after it was hit by force eight winds.
One yachtsman lost the tips of his fingers and another suffered severe head injuries and broke his wrist. Coastguards dealt with 15 incidents in four hours and the lifeboat from Yarmouth on the Isle of Wight was called out three times in two hours.
Captain Dan Bradby, secretary of the organisers, Cowes Combined Clubs, said: 'There was nothing wrong with the conditions at all. When the wind gets up, nuts and bolts fall apart.'
The Duke and Prince Edward were among the day's competitors, but were unhurt. They finished fifth in the Sigma class, their best Cowes Week placing.
Off the Welsh coast, a 'major catastrophe' was only narrowly avoided as rescuers pulled 65 children from the water after 18 yachts crewed by young teenagers capsized, also in force eight winds.
Their dinghies were blown over 'like nine-pins' during a race involving 273 midget boats in Swansea Bay, west Glamorgan.
Coastguards criticised the race organisers, Mumbles Yacht Club, for not calling off the event.
But John Parfitt, secretary of the club, denied it had been irresponsible. He said: 'In my opinion the coastguards over-reacted, although I do understand they had to act when they were contacted.
'Unfortunately weather conditions deteriorated after the race was started.'
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