Airfoil sail for a sailboat of which the length-adjustable mast consists of several telescoping pipes 12, 18, 20 holding individually raised or reefed sail crossbeams 44, 48, 52 with sail coverings spanning the vertical spacings between said crossbeams. Each crossbeam comprises several horizontal crossbeam sections connected to each other by vertical hinge shafts and jointly corresponding to a symmetric airfoil, which are pivotable for each crossbeam, by a motor adjustment drive, to curvatures optimally matching the wind conditions.