There is disclosed an improvement in wave motors for propulsion of boats, of the type comprising a supporting structure connected to the boat and extending downwards into the water, and a tilting element connected to the supporting structure, the tilting element being adapted to tilt when the boat is moved by the waves. The motor according to the invention is provided with force applying devices always trying to bring the tilting element back into a neutral position when it is angularly displaced away from this, thereby increasing the efficiency of the wave motor.