Supermaxi Wild Oats XI finished the gruelling Sydney to Hobart race in record time late Wednesday, but confirmation of its ninth line honours win will be delayed by a protest from second-placed LDV Comanche.

Wild Oats completed the 628-nautical mile (1,163-kilometre) bluewater classic in a time of 1 day, 8hrs, 48min and 50sec, several hours inside the previous record set last year.

The 100-footers had been in a fierce battle down Australia's east coast to the finish line at Hobart's Constitution Dock Wednesday, swapping the lead several times.

But the epic contest might not be over, with Comanche set to lodge a protest against Wild Oats following a near-collision exiting Sydney Heads on Tuesday in which the latter boat appeared to tack too close to her rival.

An international jury is expected to assess the evidence at a hearing Thursday, local media reported.

With Comanche finishing just 26min and 34sec behind Wild Oats, a possible punishment such as a time penalty could determine which yacht is crowned the winner.

"I think (the incident) was totally innocent and we should be able to defend ourselves against that situation pretty clearly," Wild Oats skipper Mark Richards told reporters in Hobart.

"We did exactly what we had to do in that situation -- keep the boat safe and in one piece -- and that's what we did. I'm not concerned about it at all. If those guys want to protest... that's their call."

The 103-strong fleet, whittled down to 100 after three yachts retired, benefited from ideal wind conditions after a spectacular start from Sydney Harbour on Tuesday.

The favourable weather had raised expectations the 2016 record time of 1 day 13hr 31min 20sec, set by Perpetual Loyal (renamed InfoTrack this year), would easily be broken.

The fast-paced race slowed significantly as the big boats entered the notoriously sluggish Derwent River in Hobart, but this did not stop Wild Oats from comfortably smashing the record.

- 'Pretty amazing' -

This was the strongest line-up of supermaxis to contest the Sydney to Hobart, with all four favourites to take this year's title having won line honours in previous races.

Thousands waited for the leaders to arrive in Hobart as the sun set over the southern island city, while spectator boats surrounded the supermaxis as they entered the harbour.

There were jubilant scenes for Wild Oats and her supporters after she finished, with Richards and his 20 crew members spraying champagne over each other despite uncertainty about the final outcome.

"To have nine wins and three race records... it's a pretty amazing story really," Richards added.

"Very, very proud to be a part of it. It's been a great experience."

The record finish was a relief for the Oatley family, which own Wild Oats, after their yacht had to retire from the last two races.

"It's been an exciting win. As a family we've got to work out what we're going to do going forward, but she's a great boat, she's proved it here and we'd love to see her back again," owner Sandy Oatley said.

Wild Oats had earlier closed the gap on Comanche helmed by Jim Cooney, even though she sailed "bare-headed" -- mainsail-only -- for some time after damaging the topsail, which is suited to the conditions.

The lead changed between the two boats as they near Hobart, but the lighter Wild Oats took advantage of the weaker wind conditions in the final stretch to pull ahead.

Currently in third place was Black Jack, followed by InfoTrack, with Hong Kong businessman Karl Kwok's 80-footer Beau Geste fifth.

In the race for the Tattersall Cup (overall winner) -- the handicap honour for the vessel that performs best according to size -- Matt Allen's new TP52 Ichi Ban was leading the charge ahead of Wizard.