With their enormous curved foils, the IMOCA 60 class has pushed the boundaries of offshore foiling, but at present class rules prohibit T-foils on rudders, which would allow the 60s to fly for more prolonged periods.
Louis Burton, who finished 3rd in the last Vendée Globe, recently developed an experimental load-bearing rudder foil for his Sam Manuard-designed Bureau Vallée II (the former L’Occitane, a last generation design), which saw the IMOCA fully foiling, at a consistent height and speeds of around 33 knots, for sustained periods, as these video stills show.
Burton explained: “Our IMOCAs fly, more or less, on foils, but there is no forward plane on the rudders so that makes us pitch up, then down again, the nose up. We had this spare third rudder in the…