An extraordinary design

Overshadowed by the Greenpeace ramming was the unusual concept of Le Defi's FRA-69. John Roberson reports

Side on the stern looks like it could be from a challenger of 100 years ago

These two features are not unrelated in design terms, but it is difficult to understand the thinking behind the use of this particular combination. The long overhang is nothing new in boats used for America's Cup competition, its primary purpose generally being to increase the waterline length as the boat heels.

However, overhangs normally have a very small angle to the surface of the water, so that waterline length increases as soon as the boat starts to heel, and continues to increase through further heeling. Also it has been popular practice, dating back to the days of Australia II, for the underside of the overhang to be flat, thereby extending its width, and allowing the increased waterline length effect to kick in sooner.

Admittedly, at the launching, we did not see the boat in full sailing trim, and she undoubtedly has more weight to go in her, even if only sails and electronic gear. Luc Gellusseau, the motivation behind the French team, agreed there was more weight to be added to the boat, but when asked how much this would increase the waterline length, replied laconically, "enough".

The difficulties in understanding the design concept of this boat, are that with the stern overhang cocked up as a higher than expected angle from the water, in its static state it has to sink a lot further into the water, for every added inch of waterline length, or be trimmed heavily by the stern.

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