Abstract: A torque transmitting device and related a marine propulsion system include an adapter that comprises a first portion shaped to engage in torque-transmitting relation with a propulsor shaft of the marine propulsion system so that rotation of the propulsor shaft about the axis of rotation causes synchronous rotation of the first portion about the axis of rotation. A second portion is shaped to engage in torque-transmitting relation with a propulsor hub of the marine propulsion system. The second portion is connected to the first portion by a plurality of elongated torsional members that are integrally attached to at least one of the first and second portions. The elongated torsional members are resilient so as to allow the first portion and second portion to rotate relative to each other about the axis of rotation.

Abstract: A marine propeller is provided with a valve that progressively blocks exhaust flow into aerating relation with the blades of the propeller as the propeller rotational speed increases. A piston within a housing moves radially outwardly, in response to centrifugal forces, as the propeller increases in rotational speed. This movement progressively blocks an aperture that allows the flow of exhaust gas into the region of the propellers. In certain embodiments, a secondary flow path is allowed even when the piston has moved to its extreme outward radial position.