In the biennial event's 86th year, 346 yachts - a record number - lined up for 611-mile race which will take them from the Solent into the Celtic sea where they will round the Fastnet rock off the southern coast of Ireland before turning back toPlymouth and the finish line.
At 1100GMT on Sunday the first gun fired to signal the start of the multihull class and that was shortly followed by the Monohulls.
"The forecast I had this morning was for light to moderate," said the Royal Ocean Racing Club CEO, Eddie Warden-Owen. "There is a low building up off Icelandwhich could influence the amount of wind that they get but it won't be the typical low pressure system coming through with strong winds so to cut a long story short it's not going to be a record breaking race but it will be a tough race for them they will have to beat to the rock up the Irish sea.
"I think it is going to be fairly easy out of the channel but as you know with the headlands and with the strong tide it's never easy going out through the Solent and into the channel.
"I think it's a challenge for a huge number of people. It's their Everest. It is the Everest of sailing. To get top the rock and back safely and to race and push the boat hard with your team that is what the spirit of the Rolex Fastnet race is about. It is getting there and back. If you have the opportunity to push hard and win, even better."
British entrant Ran 2 is attempting to win a third-successive title which has never been achieved in the race's history.
The first Monohulls are expected to arrive in Plymouth on Tuesday (August 13).