The crew of the Sydney-Hobart yacht departs as a storm threatens

Crews from more than 100 yachts set off for a ‘boat-breaking’ Sydney-Hobart yacht race on Thursday, with gale force winds and high seas forecast for the grueling bluewater classic.

Under blue summer skies, spectators crowded onto boats and lined the shore of Sydney’s windswept harbour, as a gun start set the fleet on a run for the open ocean.

In a dramatic opening match, reigning line honors champion LawConnect lost an early lead when one of her sails failed to deploy.

Comanche, a four-time line honors champion and event record holder, took over as the frontrunner.

By late evening the Comanche was speeding south along the east coast of Australia with a lead of more than eight nautical miles on LawConnect.

LawConnect beat Comanche to win by just 51 seconds last year and the two 30m supermaxis are expected to battle for line honors again.

Levend, the overall winner of last year’s Tattersall Cup, which takes boat size and other factors into account, was the first casualty of this year’s race, retiring due to reported engine problems.

Of the 104 participants at the start of the race, 102 remain after the withdrawal of Alive and the two-handed Transcendence Rudy Project, which was discontinued.

Race crews face gales, gales and big waves as they sail south and then tackle the infamous Bass Strait towards the Tasmanian capital of Hobart.

Weather is a crucial factor in the 628 nautical mile event, first held in 1945. (AFP)