Sydney Harbour was abuzz with spectators on land and water on Thursday, as the race cannon was sounded at 1pm. Despite wind speeds of up to 20 knots, thousands were packed around the heads to watch the supermaxis battle their way into the open sea.

At the same time, McKay and his team jumped on their bikes from the Cruising Yacht Club of Australia and headed south.

First meeting through touch rugby, Owen taught McKay how to sail in 2005 before McKay joined the Mahligai crew for the 2009 and 2013 bluewater classic. This year, the friends decided to make things a bit more interesting in an effort to raise money for the Black Dog Institute.

"When you're on the Hobart, it's the best part of 100 hours, so you have a fair bit of time to come up with different ideas," McKay said. "One of them was to see if it'd be possible for bikes to get down to Hobart in a similar time to the yachts. As I say, it all depends on how the wind blows."

The cycling team will take the Spirit of Tasmania between Melbourne and Devonport.

"We are hoping there is a gym so we can hop on the exercise bike," McKay said. "The great thing is, we will know where Mahligai is, but they won’t know where we are."

Owen, who is taking part in his 13th Sydney to Hobart this year, admits he is a "little bit worried" the cycling group may take out the race.

"What’s good for us is good for them," he said. "They want tailwinds as well. I think the last thing they want is headwinds. But looking at the forecast, we're actually looking at a reasonably quick trip."

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Concerns over a potential delay due to smoke haze were quickly forgotten as the fleet of 157 headed out of the harbour in perfect conditions on Thursday. Four starting lines were required to accommodate the huge number of entrants for the race's 75th year. It is the largest fleet since the 50th anniversary total of 371.

InfoTrack led the start in a two-horse race with Scallywag in the harbour, with Wild Oats tracking behind. But line-honours favourite Comanche was quick to make up for a slow start to the race, sitting at the front for the rest of the afternoon once the pack reached open seas.