The present invention provides a wind and wave power generation system including a platform (12) and a wind turbine (16) rotatably mounted on a tower (32) and provided with an actuator (34) for changing the yaw angle of the turbine blade (38) relative to said tower (32). The system further includes a sensor (118) for detecting at least yaw motion of the platform and a controller (56) for causing actuation of the actuator (34) to cause movement of the rotor so as to at least partially correct detected yaw motion.