Switzerland's Alinghi sailing team, defenders of the America's Cup, have chosen a giant catamaran to meet US rival Oracle's challenge.

The slender craft with two 27.4-metre long hulls is the Swiss team's response to the huge trimaran that Oracle launched last year during the legal battle over sailing's most prestigious regatta – a battle which Alinghi eventually lost.

The catamaran was inside a tent at the boatyard on Lake Geneva ahead of an expected launch on July 8.

It includes an even longer fixed central boom for a headsail and draws on some designs used for lake racing to allow a wide variation in the sail configuration and rigging, Dutch designer Rolf Vrolijk said.

"What you can gain in speed with the hulls is in the end less important than the gains from the rigging and the sails," he told the Tribune de Genève newspaper.

However, the exact configuration, including the mast, and the other dimensions were not revealed, while parts were kept hidden, according to local media allowed into the high-security tent to see the boat. Estimates for the height of the mast ranged from 48 to 50 metres.

The Swiss team declined to give any details on any of its work.

Bankrolled by billionaires Ernesto Bertarelli and Larry Ellison respectively, Alinghi and Oracle are due to fight out their duel on the open seas by next year.

The venue for the 33rd running of the race – which is up to Alinghi – has yet to be decided, with speculation over a choice between Valencia in Spain, where Alinghi won the previous America's Cup in 2007, and the coast of Dubai.

swissinfo.ch and agencies

In compliance with the JTI standards

More: SWI swissinfo.ch certified by the Journalism Trust Initiative