Two killed in wild weather on Sydney-Hobart yacht race

Two sailors have been killed in separate incidents in the treacherous Sydney to Hobart yacht race, officials said on Friday, as a string of yachts retired in powerful winds and high seas.

One of the crew members, 55-year-old Roy Quaden on Flying Fish Arctos, was hit on the head by a boom as the fleet raced down the New South Wales coast, race organizers said.

The other man, 65-year-old Nick Smith, was struck by the main sheet aboard Bowline and thrown across the boat, said David Jacobs, vice commodore of the Cruising Yacht Club of Australia.

"Unfortunately, he hit his head on the winch, and that's what killed him," Jacobs said, revising earlier official reports that both sailors had been hit by booms.

Other crew tried to revive the two Australians but were unsuccessful. They were the first fatalities in the 628-nautical mile bluewater classic since 1998.

Weather conditions played a part in the deaths, Jacobs told reporters, with one of the boats facing 30-38 knot winds and seas of two-to-three metres (six-10 feet).

"They're challenging conditions. You only need to be hit broadside by a wave and it will knock you across," Jacobs said, adding however that the weather was not "extreme" for ocean racers.

- 'Shaken' -

In a night of drama, one man was also swept overboard from the yacht Porco Rosso and carried far out before being rescued by his crew, Jacobs said.

He promised an investigation by the yacht club to help improve safety in the event but said the race would go on.

Crews on the two yachts that lost men had been hard hit, said New South Wales marine area command superintendent Joseph McNulty.

"Both those crews are doing it pretty tough at the moment. They are shaken up by what they've seen and what they've had to do," he told reporters.

Prime Minister Anthony Albanese said it was "heartbreaking that two lives have been lost at what should have been a time of joy".

So far 21 yachts -- including race record holder Comanche -- have pulled out from the fleet of 104 that left Sydney Harbour on Boxing Day bound for the Tasmanian capital, organizers said.

Many were dismasted or suffered damage to mainsails and other equipment.

- 1998 storm deaths -

Weather is a critical factor in the race, first held in 1945, with wind and sea conditions often changing rapidly as yachts head south and then tackle the notorious Bass Strait.

The 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.

Comanche's retirement with a damaged mainsail overnight left the door open for supermaxi rival LawConnect to win line honours for the second straight year.

Comanche, which surged over the finish line in one day, 9 hours, 15 minutes and 24 seconds to set a new mark in 2017, was leading when she pulled out.

LawConnect held a lead of more than 14 nautical miles by early Friday evening over nearest rival Celestial.

Alive, last year's overall winner of the Tattersall Cup, which takes into account boat size and other factors, was the first to drop out this year, retiring with engine issues.

Other former Tattersall Cup winners forced out included Wild Oats, Centennial (formerly Celestial), and Porco Rosso (formerly Victoire). Three-time overall winner Love & War remains in the race.