Phil Robertson has skippered Canada's to finishes of fourth and second in the opening races of the New York Sail Grand Prix on the Hudson River before a dying breeze forced the third fleet race to be abandoned.

Canada sit atop a crowded leaderboard with 16 points. Just five points separate the top seven teams in the 10-boat fleet in tech billionaire Larry Ellison's global league.

Sunday's two fleet races plus the podium race will be huge, with teams still scrambling for positions going into Season 4's final regatta in San Francisco, which will culminate with the $US2 million ($A3 million), winner-take-all Grand Final among the top three crews on July 14.

Switzerland won the second fleet race and are second with 15 points, followed by New Zealand with 14. The Kiwis, who lead the season standings, went 5-3 on Saturday.

Great Britain, who won the first fleet race, also have 14 points and are fourth. Three-time defending SailGP champion Tom Slingsby and Team Australia went 3-6 and are fifth with 13. Slingsby is a former America's Cup champion and an Olympic gold medallist who will helm the New York Yacht Club's American Magic in the 37th America's Cup later this year.

Peter Burling, the two-time reigning America's Cup champion helmsman and a three-time Olympic medallist, came into the regatta with an 11-point lead over Spain, with the Aussies another point back.

The Kiwis are in a strong position to be on the start line for the Grand Final and they could strengthen it with a good performance this weekend.

The third fleet race was abandoned shortly after the start when the wind dropped below 3.5 km/h. While there is no official lower-end wind limit, the conditions were deemed too light to ensure a fair race.

Robertson, a New Zealander, said the light, shifty winds and a strong current led to "extremely tricky" racing.

"There's a lot of current as well, so the boat feels really horrible with current going in all different directions," he said.

"It's frustrating at times."

Team USA, hoping for a strong showing on home waters, finished last in both races and have now finished 10th in five straight fleet races. However, the Americans are ninth overall because Germany started the regatta with a minus-four point penalty after hitting Australia in practice racing on Friday and then had finishes of 8-9.