BMW Oracle has put a cat among the pigeons with the launch of its new hull, USA-87. The ‘unveiling' - although it was more of an enshrouding than an unveiling - of the new yacht posed more questions than it answered, with a bowsprit clearly on display but even more intriguingly, the positioning of the mast a good 6 or 7 feet further forwards than on most modern-day ACC boats. What could possibly be the reason for that? Well, it has certainly got tongues wagging about what lies beneath the hull. From the beginning of this year teams have been allowed to use skirts to disguise the undercarriage of their boats, and so it is difficult to say exactly what is going on beneath USA-87's skirts. But the unorthodox mast position has certainly got pundits and rival teams wondering if Larry Ellison's crew are chasing the Holy Grail of America's Cup yacht design - the twin-keel.

Many teams have tried and failed to win the Cup with a magic bullet. Occasionally someone makes a breakthrough and sweeps to victory. Australia II is the most famous example, with Ben Lexcen's winged keel credited with wresting the Cup from the New York Yacht Club. Even then, that radical design only just clinched victory from Liberty on the final run of the final race. It was hardly a whitewash, but for once the radical solution proved to be a winning one.

Alinghi's victory three years ago, on the other hand, was seen as a natural evolution from previous winning designs by Team New Zealand, while the one team that seemed determined to start from scratch was Team New Zealand itself. The Kiwis were convinced their double-skinned rule bender, the ‘hula', would walk all over the Swiss, but in the end the ‘hula' proved to be a load of hooey. SUI-64 - one of the oldest, but one of the most developed boats in the 2003 fleet - won 5-nil. A clean sweep for conservatism.

Even so, the twin-keel debate continues. It is an argument that has been raging since the very early days of the Cup, when in 1891 the American designer, Nathanael Greene Herreshoff, produced a radical yacht called Dilemma, an apt name for a twin-keeler if ever there was. Herreshoff designed six successful America's Cup defenders in his time, so this was no mad professor tinkering around in his garden shed. If such an eminent designer thought there was something to the concept, then surely it must merit further exploration. Ever since, designers have worked hard to prove that a principle that shows such merit in theory can be translated into practical success on the water. No one could truly be said to have succeeded, although there have been just enough glimmers of hope to keep the twin-keel dream alive.

Interest in the twin-keel concept peaked in the 1990s, a hundred years after Herreshoff's Dilemma first posed the question. With the 12-Metres put out to grass after the thrilling showdown of Fremantle 1987, San Diego 1992 was the first outing for the new America's Cup Class, and yacht designers went to town on some outlandish concepts. Four different teams trialled versions of a tandem or twin-keeled configuration, although not all of them enjoyed success in such radical mode. However the Bruce Farr-designed NZL-20, known then as the ‘Little Red Sled', showed real potential with its twin-keel and controversial bowsprit. Paul Cayard and the Italian team Il Moro di Venezia disputed the use of the bowsprit and the resulting protest appeared to fluster the Kiwis who ended up losing the Louis Vuitton Cup to the Italians. But the red boat certainly wasn't slow.

Other Cup campaigns have since flirted with the twin-keeled concept, such as the first ever Swiss challenge in 2000, Be Happy. Following the woeful performance of their radical boat, Be Happy turned out to be a good piece of self-help advice for the dejected Swiss campaign. And then in 2002/03 GBR Challenge made a late bid for twin-keeled glory with their second boat GBR-78, although this proved to be not only slow but virtually impossible to sail in a straight line.

One of the driving forces behind GBR Challenge's decision to go down the twin-keel route was David Barnes, the syndicate CEO from New Zealand who had been part of the NZL-20 campaign a decade earlier. Clearly he had seen sufficient potential from the ‘Little Red Sled' to want to give it another go, so while it was an unmitigated disaster for the Brits - who were short of time, money and experience - perhaps it could yet come to something for BMW Oracle.

Chris Dickson's team have oodles of time, money and experience under their belts already, and they have launched USA-87 more than a year before the Louis Vuitton Cup Finals. And of course they have Bruce Farr, the very man who designed the ‘Little Red Sled', so for him it must be an exciting trip down memory lane. Not only does he have the previous experience of NZL-20 to draw upon, but he has the seemingly unlimited resources of BMW Oracle at his disposal. If ever there was a chance to explore the full potential of the twin-keel concept, this must surely be it.

BMW Oracle's navigator Peter Isler reports that the team has already had some good two-boat testing sessions between USA-87 and their benchmark boat US-76. He comments on the BMW Oracle official website: "The BMW Oracle team is really pleased with 87's ‘out of the box' performance, and we are now working through the methodical path of learning how to sail it faster, and faster." Well, from that we can't tell whether or not USA-87 is yet sailing faster than the conventional USA-76, but Isler certainly sounds bullish about the new boat's prospects. Have they found the Holy Grail after all?

Meanwhile other teams still don't know if they're even going to be on the start line as financial problems continue to dog some of the smaller teams. One team that appears to have elevated itself beyond that point is K-Challenge, the French team now to be known as Areva Challenge. Areva is the French nuclear power company that sponsored Le Défi last time in Auckland. Le Défi has now transmuted into the China Team, and so effectively ruled itself out of consideration for sponsorship by a French company such as Areva - even though in terms of sailing personnel Pierre Mas's team is probably more French than K-Challenge.

Areva's decision to back Stéphane Kandler's challenge will be a popular one, as skipper Thierry Peponnet and his cosmopolitan team were the giant-killers of the 2005 America's Cup Act season. More than any other campaign K-Challenge has been punching above its weight. With a small sailing and shore team, very limited financial resources and the oldest boats in the fleet, K-Challenge produced some stunning results last year - not least those final-day match racing victories over Alinghi and Emirates Team New Zealand in Sicily last October. Now with Areva's backing it will be interesting to see if Kandler, Peponnet and the team can convert those signs of potential into a package truly capable of taking on the Premier Division.