Aera's skipper Jez Fanstone firmed his grip on the Sydney to Hobart overall IRC handicap trophy as fading winds ensured most of the fleet dropped off the pace.

A total of 21 yachts crossed the line by early evening on the fourth day, with another 13 expected into the Derwent River before dawn.

Fanstone was breathing easier after Aera's main rivals limped across the finish line on Thursday night.

Handicap contender First National Real Estate - skippered by last year's overall winner Michael Spies - crossed the line at 6:11pm local time on Thursday night.

However, First National and the other leading 40-footers - including Nips-N-Tux and Chutzpah who also finished on Thursday evening - failed to make a dent in Aera's provisional IRC standings lead.

The classic 31-year-old wooden boat Love and War has no prospect of displacing Aera despite her low rating (handicap) but is ranked fifth overall in computer calculations.

Aera, owned by London-based yachtsman Nick Lykiardopulo, provisionally leads the IRC standings ahead of line honours winner Nicorette, owned by Sydney-based yachtsman Ludde Ingvall.

Aera is now provisionally the 12th overseas yacht to win Australia's great bluewater race.

Aera has been the provisional overall winner since Wednesday afternoon, when it finished fourth in an adjusted time more than four hours better than line honours champion Nicorette.

Cruising Yacht Club of Australia commodore Martin James on Thursday said the dying breeze in Storm Bay meant the chance of Aera being beaten was getting "very thin indeed".

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