Abstract: A marine propulsion system drive unit is provided with a polymer layer to protect its outer surface from abrasion and corrosion. The polymer layer is injection molded around the outer surface of a metallic gear case structure or drive shaft housing to provide a coat which is approximately 3 millimeters thick and which will resist scratching and corrosion. The polymer layer can be a glass filled polymer or a carbon filled polymer. An adhesion promoter can be used to enhance the bonding and intimate contact between the inner surface of the polymer layer and the outer surface of the metallic gear case structure or drive shaft housing.

Abstract: An engine is made by providing a layer of material between the outer surface of a cylinder liner and the inner surface of the cylinder opening within an engine block. The material can be a polymer or a ceramic. Polyether ether ketone or polyethylene terephthalate can be a polymer used for these purposes. Zirconia or yttria can be ceramic used for these purposes. An electro-deposited paint can serve as the layer of thermally insulative material.

Abstract: A torque transfer mechanism for a marine propulsion system provides a connector mechanism, a first torque transfer mechanism, and a second torque transfer mechanism. A plurality of rods can provide the first torque transfer mechanism and a polymer component is shaped to provide the second torque transfer mechanism. All torque below a preselected magnitude is transferred through the first torque transfer mechanism and, for magnitudes of torque above the threshold, torque is transferred by both the first and second torque transfer mechanisms. The connector mechanism has an outer surface that is not used to transfer torque between it and an inner hub of a propulsor.

Abstract: A multilayered submersible structure has an outer coating that is disposed in contact with water in which the structure is submerged, a current distribution layer or charge distribution layer, an electrical conductor connectable in electrical communication to a source of electrical power, and a support structure. By selectively energizing the current distribution layer, or charge distribution layer, chemical and ionic changes can be caused in the water immediately adjacent the outer coating or layer to inhibit the growth of marine organisms on the outer surface of the submersible structure.

Abstract: A marine propulsion system is made with an oil sump that is a polymer material that is nonanodic and nonmetallic. As a result, the possibility of a galvanic circuit being created within the structure of a drive shaft housing is significantly reduced or eliminated. The result is the enhanced operation of the marine propulsion system without corrosion and the resulting destruction of the internal components within the drive shaft housing.

Abstract: A torque transmitting device for use in conjunction with a marine propulsion system provides an adapter that is attached in torque transmitting relation with a propulsor shaft for rotation about a central axis of rotation. The first insert portion is attached in torque transmitting relation with the adapter and a second insert portion is attached in torque transmitting relation with a hub of the propulsor hub which can be a marine propeller or an impeller. A third insert portion is connected between the first and second insert portions and is resilient in order to allow the first and second insert portions to rotate relative to each other about the central axis of rotation. The adapter is shaped to prevent compression of the first, second, and third insert portions in a direction parallel to the central axis of rotation.