Australian supermaxi LawConnect took back-to-back line honours in the Sydney-Hobart ocean race early Saturday, leading a fleet shaken by the deaths of two sailors in wild weather conditions.

LawConnect, the 100-foot defending champion skippered by Christian Beck, arrived first in Hobart after main rival Comanche dropped out with a damaged mainsail on the first night.

The crew navigated to victory along the final stretch of Tasmania's River Derwent in the dark, early hours of the morning after a day-and-a-half of drama since the fleet departed a sun-splashed Sydney Harbour on Boxing Day.

LawConnect crossed with a winning time of one day, 13 hours, 35 minutes and 13 seconds, according to the official race tracker.

Fans on the dock cheered her arrival but there were no signs of the usual celebrations aboard, a livestream by the race organisers showed.

Celestial, a 70-footer with hopes of winning the Tattersall Cup for the overall handicap race, was in second place, finishing a little over two-and-a-half hours later.

Wild Thing came in third.

"It was challenging conditions, probably the roughest race I've done out of the 11 that I have done," said LawConnect sailing master Tony Mutter.

"But we came through okay. We didn't break too much stuff, and people are okay, we have got a few bumps and bruises," he told reporters in Hobart, explaining that his skipper was unable to appear because of a stomach bug.

The crew faced 35-45 knot gales downwind out of Sydney, big waves and tricky currents, he said.

"We are obviously hugely disappointed in the news that we heard during the race with the loss of a couple of fellow competitors and our heartfelt condolences go out to all the friends and family," Mutter said.

"We are obviously not doing any celebrations on the boat and we will do that quietly later on."

- First fatalities since 1998 -

Weather is a critical factor in the 628-nautical-mile race, first held in 1945.

This year's initial fleet of 104 was pummelled by gale-force winds and big waves as it raced southwards along Australia's eastern coast before tackling the treacherous Bass Strait.

Two sailors were killed in separate incidents in rough weather on the first night, officials said.

The boom on Flying Fish Arctos hit 55-year-old Roy Quaden on the head; and the main sheet on Bowline struck 65-year-old Nick Smith who then collided with a winch, said David Jacobs, vice commodore of the Cruising Yacht Club of Australia.

Fellow crew members tried to revive both men but failed, officials said.

The two fatalities were the first in the race since 1998 when six men died, five boats sank and 55 sailors were rescued after a deep depression exploded over the fleet in Bass Strait.

Twenty-seven yachts including supermaxi Comanche have retired so far, organisers said, many of them either dismasted or suffering damage to sails, engines and other equipment.

A four-time winner of the bluewater classic, Comanche holds the record for completing the race in one day, 9 hours, 15 minutes and 24 seconds in 2017.

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