A hydrofoil sailboat with a slender hull and a foil-shaped sail spaced laally therefrom. The hull has one flat side facing the sail and one convex side. The sail is inclined from the vertical toward the hull and is supported at its base ends by a pair of freely swiveling waterskis. The hull supports a rudder at each of its ends, the rudders being hydrofoils with their flat sides facing the sail. The length-to-width ratio of the hull is no less than 5:1 and the inclination of the sail about 30.degree. from the vertical.