Abstract: Apparatus for steering a hydrofoil ship by the combination of one or more trailing-edge or spade rudders in combination with means for controlling the side forces on a vertical, fixed strut or horizontal foil which pierces the water. The means for controlling side forces comprises an elongated roller or rollers mounted on the leading edge of the strut or foil. In the case of the vertical strut, the roller is stationary and has no effect when the craft is not turning. However, when turning, the roller is rotated about its own axis in the direction of the turn to produce a pressure decrease which minimizes the resistance to water flow on the side facing the direction of turn. In the case of a horizontal foil, the roller rotates in a direction to decrease pressure on the upper surface and increase it below, thereby creating greater lift.