BMW Oracle's stunning victory in Friday's opening race of the 33rd America's Cup drew extravagant praise from owner Larry Ellison for his boat's eye-catching carbon fibre and kevlar wing-shaped sail.

At 68 metres, the sail is more than twice as long as a Boeing 747's wing and was a key reason for the US challengers' crushing defeat of Swiss holders Alinghi off Valencia, Spain.

"The piece of kit that we're most proud of is the wing," software billionaire Ellison said.

"It's a brilliant engine for this boat."

Air flows around the "wing sail", creating higher pressure on one side and thrusting the giant trimaran forward in the same way an aircraft is lifted by its wings.

Alinghi considered building a similar sail but decided they did not have enough time before the best-of-three regatta.

Their catamaran uses a more conventional mainsail attached to a mast 17 storeys high.

Ellison said there had been a good deal of discussion within the team before the decision had been taken to design and build the wing sail and noted that the technology was not new.

Stars & Stripes, the 1988 America's Cup winner, had a similar wing sail 33 metres tall.

"It wasn't like (BMW Oracle chief executive) Russell Coutts just dropped me an e-mail saying we'd like to build a wing," Ellison said.

"We talked about it quite a lot and the consensus in the team was that it was going to be the most powerful engine for the boat and so we went ahead and did it."

Alinghi owner, Swiss billionaire Ernesto Bertarelli, told a news conference the race had shown the wing sail was quite versatile and that it had possibly made the difference in the 40 nautical mile duel.

Asked how Alinghi might be able to coax more speed out of their catamaran, Bertarelli said: "I don't think we're going to be able to build a wing from now until Sunday (today) so that's not going to happen."

Alinghi skipper Brad Butterworth was also impressed with the speed of the BMW Oracle team, who suffered a poor start but swiftly overhauled the defenders and finished more than 15 minutes ahead.

"I think they certainly showed how fast they can get their boat going. They couldn't have come off the line in a worse position and they ended up in a very strong position," Butterworth said.