Wild Oats XI sailed between Sydney Heads and into open ocean with a narrow lead over its main rivals Investec Loyal and Wild Thing in the 67th edition of the race. Crew immediately hoisted a spinnaker and Wild Oats headed down the east coast of New South Wales state with a 20 knot tail wind and on heavy swells.

The fleet was expected to sail into a southerly front on Monday night with headwinds of up to 40 knots, making any challenge to Wild Oats' 2005 race record time unlikely.

Wild Oats XI struggled in the opening minutes of the race with a winch failure and had to give way to Investec Loyal as the yachts engaged in a tacking duel in the famous harbor. But the race favorite eventually showed its speed and passed through the heads into the open seas with a lead of several boat lengths.

When positions were plotted after 5-1/2 hours of racing, Wild Oats XI held a 4.5 nautical mile lead over Investec Loyal with Wild Thing a further three miles back.

Two yachts, Alchemy and Maluka of Kermandie, were forced to turn back and restart after breaking the start line early.

Yachts were expected to enjoy only a few hours of favorable sailing conditions before encountering the southerly front that passed through Victoria state on Sunday, bringing thunderstorms, high winds and hail.

"It is a pretty interesting looking forecast, there is a bit of everything in it, and it promises to be a tough race," Wild Oats XI skipper Mark Richards said.

Cruising Yacht Club of Australia commodore Garry Linacre said weather conditions could produced an intensely tactical race.

"There will be some fantastic speed set by the maxis down the coast," Linacre said. "They will probably get 100 nautical miles under their belt before the change comes in, which is almost one-sixth of the race over, in just a few hours.

"Record-breaking speed but then the breeze will come the other way with that traditional southerly buster type weather.”

Investec Loyal, which was second across the line last year and has since undergone modifications, looms as the largest rival to Wild Oats XI's bid for a sixth line honors win. Lahana, which has finished second, third and fourth in previous years competing under three different names, was also seen as a leading chance.

Teenage round-the-world sailor Jessica Watson was skippering the youngest crew ever to compete in the race. The 17-year-old last year become the youngest person to sail around the globe solo, nonstop and unassisted.

She took the helm of the Sydney 38-class boat Another Challenge for the 628-nautical mile (723-mile) race, which travels south along the New South Wales coast, across often treacherous Bass Strait and up the Derwent River to Hobart, the capital of the island state of Tasmania.

The yachts and their crews often negotiate hazardous conditions during the Sydney to Hobart. Five boats sank during the 1998 race resulting in the deaths of six sailors.

On Saturday, Rob Webb, the New South Wales bureau of meteorology regional director, said the swell from tropical cyclone Fina is expected to affect the fleet on the first afternoon and evening, but won't have a major impact on the race.

Adrienne Cahalan, the co-navigator aboard Wild Oats XI, predicted her boat could post a similar time to the two days, seven hours and 37 minutes it took to win last year.

But she said the record of one day, 18 hours, 40 minutes, 10 seconds set by Wild Oats XI in its 2005 debut would not be threatened.

"I'm afraid it (the race record) is out of the window, there's too much southerly in this forecast," Cahalan said.