Less than a minute after the the Sydney to Hobart starters gun's boom reached crowds clustered around the perimeter fence of HMAS Watson, Comanche raced into prime view, screaming past Camp Cove and leaving its most serious rival in its wake.

With cheers for the starting gun merging into applause for the new American 100-footer, it was clear that the hype was justified.

The 70th Sydney to Hobart yacht race got underway on Friday, with a record 117 yachts in contention for the title in the classic ocean race.

With no fewer than eight helicopters overhead, Comanche and defending champion Wild Oats XI were followed by Ragamuffin and Perpetual Loyal as they sped from the Nielsen Park starting line. 

Pushing into the Tasman Sea, the fast-moving fleet churned waters, with hundreds of spectating vessels of all sizes and classes along for the ride, shadowing as best they could the ferocious supermaxi yachts.

Bright sunshine and a light breeze gave little clue of what lies ahead for the armada, with lumpy waters and winds of 30 knots forecast for Friday night.

While 2014's might be a race for purists and those who have been holding out for some strong competition to take on the seemingly unstoppable Wild Oats XI, it was a family affair on the tip of South Head, where hundreds looked out to sea, binoculars held to noses and picnics spread on rugs.