Abstract: A combined clutch and torsion damper for a water jet propulsion system for boats permits the impeller to be disengaged whilst the motor remains running. The combined clutch and torsion damper has an outer ring housing with an attachment to the motor, an inner housing, concentric and within the outer ring housing, rotatably mounted on a central shaft, resilient torque transmitting connectors positioned between the inner housing and the outer housing to damper rotational forces transmitted from the outer housing to the inner housing, an electromagnetic clutch positioned between the inner housing and a clutch ring mounted concentrically on the central shaft, and a slip joint connection on the central shaft to a water jet impeller shaft via a universal joint.