Volvo round-the-world boats continued to dominate the Sydney-Hobart race yesterday after a violent storm and tornado slammed into the fleet, knocking the favourite, Nicorette, on its side and forcing 11 yachts out.

Volvo-class 60-footers, competing in the 630-nautical mile race as part of the third leg of their race around the world, filled the top six places after a torrid opening stretch down Australia's east coast.

Volvo race-leader Illbruck sailed past overnight leader Tyco early after racing neck-and-neck for most of the first 24 hours in strong south-westerly winds.

Illbruck led a group of about 14 boats past Green Cape, about 400 kilometres south of Sydney, into the notoriously rough Bass Strait for what is usually the hardest part of the race between the Australian mainland and Tasmania.

Swedish maxi Nicorette had made up some of the ground she lost during a dramatic first 24 hours and was 12 nautical miles behind the leaders in seventh place by a scheduled 2 p.m. Irish time radio-position report.

Nicorette, the defending champion, surrendered her lead when she was hit by a tornado and fierce hailstorm late on Wednesday.

Video footage taken on board Nicorette showed a huge, grey funnel-shaped cloud moving across the ocean towards skipper Ludde Ingvall's boat, preceded by a piercing howl of wind.

Ingvall's crew scrambled to bring the boat's sails down as they tried unsuccessfully to dodge the worst of what the experienced Finnish sailor likened to a "twister". Large hailstones could be heard slamming into the boat.

Ingvall said he sent all but three of his 23 crew below as the tornado approached and then hit the boat, knocking it flat and sucking it into its centre before spitting it out the other side.

"It was the biggest, most awesome and awful experience I've ever felt," Ingvall said from his boat in Bass Strait. Ingvall feared for his life as he felt himself being sucked into the air.

"I felt it was like a wrestler grabbing the back of my jacket and trying to lift me off my feet," he said.

Nicorette's mainsail was extensively damaged but her crew managed to replace the sail as the white-and-green hulled yacht began slogging her way through south-westerly winds of 25-30 knots back towards the front of the fleet.

Ingvall vowed never to sail the Sydney-Hobart again after gale-force winds hit the fleet in Bass Strait last year.

Australian Skandia, which finished second to Nicorette last year known as Wild Thing, became the first headline casualty when she suffered extensive sail damage in Wednesday's storm.

Grant Wharington's maxi had been one of only a handful of boats considered capable of stopping Nicorette's bid for back-to-back line honours.

Wharington estimated the tornado measured 500 metres (1,640 feet) in diameter at its base.

"We were expecting to see cows and motor homes and everything in it. It was really quite scary, I've never seen anything like it," he said after his boat limped back to Sydney.

By 2 p.m., Illbruck's US skipper John Kostecki had steered his state-of-the-art water-ballasted yacht to a slender lead over Australian entry News Corp, the first boat out of Sydney Harbour on Wednesday.

Swedish yachts Assa Abloy and Team SEB were third and fourth, with Norway's Djuice fifth. German-backed Illbruck won the first two legs of the round the world race from Southampton and Cape Town.

Race officials said Bermudan yacht Tyco, forced out of the second leg of the round the world race with a broken rudder, did not radio her latest position but was believed to be among the leaders.

Eleven yachts have now withdrawn from the starting fleet of 75.

SAP Ausmaid, which won the race on handicap in 1996 and 2000, and fellow Australian yacht Secret Men's Business were dismasted within 30 minutes of each other early yesterday.

This year's fleet was the smallest in 28 years, due in part to the rising costs in insurance and mandatory safety equipment which stem from the tragic events of the 1998 race, when six sailors died in appalling weather conditions across Bass Strait.