Supermaxi LDV Comanche led the fancied big boats as the gruelling Sydney to Hobart race began Tuesday, after a close call that saw the yacht almost collide with rival Wild Oats XI.

Another supermaxi, Black Jack, had led the fleet out of Sydney Harbour, with the vessels chasing a new race record amid "dream" conditions in the annual dash down Australia's east coast.

Four 100-footer supermaxis are among the 102 entries in the 73rd edition of the 628-nautical mile (1,163-kilometre) bluewater classic, viewed as one of the toughest yacht races in the world.

The large boats benefited from the light east to south-easterly winds as they sped out of the harbour in the spectacular Boxing Day launch to the event.

Black Jack was followed by Wild Oats and Comanche, with the pair sparking early drama after almost colliding.

The Mark Richards-skippered Wild Oats appeared to tack too close to its rival near the exit to Sydney Heads, leading to a protest from Comanche, helmed by Jim Cooney.

Comanche took over the lead as the vessels tracked down the coast of New South Wales state, ahead of Wild Oats and Black Jack in a close race, with the fourth super-yacht InfoTrack behind them.

Wild Oats tactician Iain Murray told reporters before the start of the race that "in all my 24 times of going down here, it's never been as good as this".

"It's very rare that you get this continually off-the-wind, cross-the-wind, wind start-to-finish sort of scenario. It's something we all dream about, really."

Murray said that because the super-yachts could reach speeds of up to 20 knots, a new line honours record for the fastest vessel could be possible.

"The numbers suggest a race record is easily achievable for I think any of the maxi boats," he added.

"These boats are capable of 20 knots. The current record is 17 something. It's just getting around the corners is the hard part."

InfoTrack, named Perpetual Loyal last year, arrived at Hobart's Constitution Dock in a record time of 1 day 13hr 31min 20sec to take the 2016 line honours title.

- Sluggish Derwent -

A big unknown will be the conditions on the Derwent in Hobart, a fickle river that could offer up windless holes which can halt a boat for hours.

The super maxis are expected to arrive at Storm Bay late Wednesday afternoon, and head into the Derwent leading to Constitution Dock at night.

"We're looking forward to some terrific sailing," said Comanche navigator Stan Honey.

"The dicey part happens after Tasman Island... we get to the Derwent at the worst time."

This is the strongest line-up of supermaxis to contest the Sydney to Hobart, with all four having won line honours in previous races.

Eight-time winner Wild Oats is hoping for another success after being forced to retire from the last two races.

The forecast continues to favour the medium-sized 45 to 55-foot boats, as well as the Oatley family's smaller entry Wild Oats X in the race for the Tattersall Cup.

The Cup is a handicap honour for the vessel that performs best according to size.

This year's race -- which draws spectators on land and in boats in Sydney -- has also attracted a record-equalling 27 internationals including from China, France, the United States and Italy.

Source: AFP