Abstract: A boat is provided having front and rear ends, a bottom and upwardly projecting sides extending upwardly to an elevation spaced above the static water line of the boat. A depending central strut (fixed or upwardly retractable) projects downwardly from the bottom and a pair of elongated downwardly convergent opposite side flexible foils including leading and trailing longitudinal edges facing in front and rear directions, respectively, of the boat are provided and have their lower ends anchored to the lower end portion of the strut. The upper end portions of the foils are anchored relative to upper portions of the corresponding sides of the boat above the static water line thereof outwardly of the boat sides and the foils are free of support from the boat intermediate the upper and lower ends of the foils.