They captured the public imagination in Beijing during a glorious gold-rush weekend in August but the 2012 hopes of Great Britain's “three blondes in a boat” were scuppered yesterday by the withdrawal of their class from the sailing event at the London Games.

Sarah Webb, Sarah Ayton and Pippa Wilson will be unable to defend their Olympic title in front of a home crowd after the Council of the International Sailing Federation (ISAF) voted to replace the women's Yngling keelboat with head-to-head match racing in an Elliott 6m.

The decision at the ISAF's annual conference in Madrid leaves the trio in limbo as they debate whether to transfer to a new boat or pursue separate Olympic campaigns. “It's a crazy decision,” Webb said. “We haven't discussed what we would like to do in an ideal world but obviously we would try to avoid racing against each other as that would be a waste. We will take the weekend to think about it and make a plan.”

Webb said it was “50-50” whether they would stay together to crew the Elliott 6m, for which they may not be suited. Their combined racing weight of 190kg in Beijing is well below the 205kg limit for the new boat making its Olympic debut in 2012, but they would have to learn new skills for the only 2012 class to feature a sequence of one-on-one contests rather than traditional fleet racing.

The change is designed to widen participation in the sport and improve it as a spectacle. Yngling is a highly technical discipline and, as one of the most expensive in the Olympics, critics argue that it is beyond sailors without big sponsorship deals.

It costs about £130,000 a year - double that in an Olympic year - to run a Yngling campaign. Webb, who was struggling to cover the team's costs and is now left with three boats with a depressed value, is unhappy about match racing at the Olympics. “It will lose its magic,” she said. “It's an amateur sport where people can turn up anywhere in the world for a weekend of racing. It will now be full of professionals and that will be a shame.”

Webb, Ayton and Wilson were part of a bumper weekend at the Beijing Games when Team GB won eight gold medals and 17 medals in total, propelling Britain briefly to third in the medals table behind China and the United States. The sailing team won six medals in 11 classes.

There will be only ten sailing events in Weymouth, which will become the first 2012 venue to be completed this month. Construction workers are finishing 150 metres of new slipway under a £6.5million project by the Olympic Delivery Authority.

The site at Weymouth and Portland National Sailing Academy was chosen by the Games organisers for its natural amphitheatre, prevailing southwesterly wind - with an average speed of 16 to 17 knots - and a low tidal range of two metres. It promises to be very different from Qingdao, a former fishing village of nine million people and a challenging venue for its light winds, strong tide and carpet of keel-embracing green algae.

The idea of hosting Olympic sailing in Portland Harbour, a former Navy base, has been in the making for 30 years but became reality after the sailing academy opened in 2005 with £7million investment, mostly from local development agencies. Sailing requires two test events, so 2010 and 2011 will be important years for the academy to demonstrate its potential as the ultimate Olympic venue.