Abstract: A surface-effect aerofoil boat having two aerofoils arranged in tandem and having a gap for a propulsion or air screw between a vertical fin and an aerodynamic rudder and wherein the aerofoils are designed as hollow bodies subdivided into compartments some of which being provided with flooding and emptying devices. The rear aerofoil seen in the direction of travel is clipped with respect to the geometry of its trailing edge in a polygonal or rounded-off manner. The gap in the plane of rotation of the propulsion or air screw is widened in its radially outer zone relative to the inner zone near the axis.