Pacesetter Comanche is being reeled in by the four other supermaxis heading into a fascinating first night of the 75th Sydney to Hobart.
Two-time line honours winner Comanche had led for most of Thursday, bar a slow start, with InfoTrack winning the battle to be first boat through Sydney Heads.
Comanche rocketed from fifth to first, as she as she got into open water away from the large spectator fleet, and led by up to seven nautical miles from InfoTrack at one stage late in the afternoon.
She powered along in favourable northerly winds of up to 25 knots, travelling across the water at a similar rate.
InfoTrack (second left) and Comanche at the start of the Sydney to Hobart Yacht race in Sydney. Source: AAP
But with the forecast change in wind strength and direction later on Thursday, it was always on the cards that her lead would be eroded.
Seven hours into the race, nine-time line honours winner Wild Oats XI had slashed Comanche's lead to four miles.
The other three supermaxis - InfoTrack, Black Jack and SHK Scallywag - were all within three miles of Wild Oats XI.
"When it gets a little bit lighter the narrower boats, the Black Jacks and Scallywags, they come into their own in those lighter conditions," Cruising Yacht Club of Australia commodore Paul Billingham said.
While the quintet of supemaxis were around race record pace, their speed dropped as the hours progressed.
The supermaxis had pulled away from the rest of the fleet with Alive last year's overall winner, in sixth place 11 miles behind fifth-placed SHK Scallywag.
The starting fleet of 157 was reduced to 155 with two retirements in the first four hours.
The Farr 55 Hollywood Boulevard, which finished 10th overall last year, suffered a broken rudder.
The 38-foot Faster Forward was forced out with steering problems.
Black Jack and Scallywag (right) leave the heads at the start of the Sydney to Hobart Yacht race in Sydney on Boxing Day. Source: AAP
Among the boats showing up well on handicap were French yacht Daguet 3, two-time overall winner Quest and 2017 winner Ichi Ban.
"The transition zone through the trough late on tonight is really going to be the key point to the ace - who wriggles out of that in good shape," Ichi Ban skipper Matt Allen said a few hours before the start.
Fears the start of the iconic yacht race could be affected by smoke were allayed by the Bureau of Meteorology earlier in the week.
"Over the next few days, we are sitting in easterly winds which means for Sydney itself and much of the NSW coast we are not going to look at thick smoke haze affecting anywhere over the water," BOM spokesperson Gabrielle Woodhouse said.
