"Comanche is an impressive bit of engineering, but she's a bit last-century," says Kay. "With a wide boat, the trick is to sail with big heel angles to get the boat out of the water." But as every Opti sailor knows, a rig is far more efficient when it's sailed upright. Kay says Comanche power-reaches at heeling angles of 25 degrees, while a DSS boat power-reaches at heeling angles of 7 to 12 degrees. Because DSS foils provide significant lift, a designer can spec a lighter-weight keel bulb, bolstering light-air performance, which has already been boosted by having a low-drag hull form.
"The gains are all over the boat, and they keep magnifying [with speed]," says Kay. Gains include raw boatspeed, stability and ride comfort, as DSS-equipped boats pitch and slam less than their canting- or fixed-keel rivals. This last point theoretically enables a more stable flow over the sail plan while also delivering a more seakindly ride.