AFP / Damien MEYER

French sailor François Gabart smashed six days and 10 hours off sailing's around the world record on Sunday producing what many pundits felt was a previously unthinkable time of 42 days, 16 hours, 40 minutes and 35 seconds.

Huge crowds of well-wishers were on hand to welcome the sailor into the port of Brest, accompanied by hundreds of small craft as he burned flares at the helm and was carried aloft to shore by his ground crew where he popped a bottle of champagne.

The 34-year-old sailor crossed a virtual finish line between the island of Ushant off France's northwest tip and Lizard Point in southwest England at 0145 GMT, comfortably beating the previous record set by compatriot Thomas Coville last year by six days and 10 hours.

Moments before crossing the finish line Gabart, a father of two and engineer by trade, sent out an emotional video showing his boat's progress on a computer monitor.

"The little blue is us, the red line is the finish. We should cut it soon, the computer says 30 seconds," he said, wiping his eyes.

The race time was announced by an observer from the World Sailing Speed Council but will be subject to checks of the boat's black box and its GPS data before final confirmation.

"I'm happy and proud to have made this lovely voyage around the world," he said in the video.

"It hasn't sunk in yet but I know it's a great time. I have cargo ships and fishing boats around me in the dark here and it all seems strange and extraordinary."

Gabart becomes just the fourth title-holder for a world record of sailing the globe solo without stopping.

Huge leaps have been made in that time -- since the record was first set in 2004, nearly 30 days have been shaved off.

The debut record holder was Frenchman Francis Joyon who completed the odyssey in 72 days and 22 hours.

British female sailor Ellen MacArthur took to the seas a year later, racing against the clock to break that record by just a day and a half (71 days, 14 hours).

She remained undefeated until 2016 when Coville set a new record of 49 days and three hours which many predicted would be difficult to topple.

AFP / Damien MEYER

Gabart, who embarked on November 4, was on a two-year-old state of the art 30 metre (98 foot) long new generation MACIF maxi-trimaran comfortably carved its way through the waves and into the record books.

Helped by good weather throughout much of the voyage, particularly during the long and arduous Pacific section, it clocked up jaw-dropping speeds of up to 35 knots (65 kilometres an hour).

He set a number of new solo race records along the way, including the fastest navigation of the Pacific (7 days, 15 hours, 15 minutes) and the longest distance covered in 24 hours (851 miles or 1,576 kilometres).

Gabart first circumnavigated the world during the 2013 Vendee Globe race -- which he won. He immediately set his sights on breaking the solo non-stop record.

Coville congratulated his record vanquisher.

"He's an incredible strategist. He already showed that during the Vendee Globe," he told AFP.

Of the four solo record holders, Gabart is the only won to have also won a competitive round the world race.

"It only confirms that he is talented, that he works hard and leads each project," said Guillaume Combescure, one of the engineers who worked with Gabart.

"He has shown that dreams are a great motivator, that anything is possible," he added.

Another illustrious sailor Michel Desjoyeaux said there was no surprise in the feat.

"The one thing we can be sure of is that Francois has a faster boat than Thomas had and if they raced head-to-head then he would be faster," he told AFP by telephone.

"And he has spent a great deal of time on a multi-hull and is completely unafraid of high speeds, he's fundamentally at ease in that environment.

Coville's boat was a ten-year-old craft that had been reconditioned rather than built to purpose.