Abstract: A marine propulsion system is for propelling a marine vessel in water. The system comprises an outboard motor that is coupled to a marine vessel, and that comprises an exhaust gas relief outlet that is located above the water when the outboard motor is at idle speed. A conduit conveys exhaust gas from the exhaust gas relief outlet to a discharge outlet located on the marine vessel.

Abstract: An outboard motor and a method of making an outboard motor provide an exhaust conduit having a first end that receives exhaust gas from an internal combustion engine and a second end that discharges exhaust gas to seawater via a propeller shaft housing outlet. An exhaust conduit opening is formed in the exhaust conduit between the first and second ends. The exhaust conduit opening is for discharging exhaust gas from the exhaust conduit to atmosphere via a driveshaft housing of the outboard motor and via an idle exhaust relief outlet and a driveshaft housing outlet in the driveshaft housing. The driveshaft housing outlet is vertically located between the propeller shaft housing outlet and the idle exhaust relief outlet. A cooling pump pumps cooling water from a cooling water inlet for cooling the internal combustion engine to a cooling water outlet for discharging cooling water from the outboard motor.

Abstract: A marine propulsion system is for propelling a marine vessel in water. The system comprises an outboard motor that is coupled to a marine vessel, and that comprises an exhaust gas relief outlet that is located above the water when the outboard motor is at idle speed. A conduit conveys exhaust gas from the exhaust gas relief outlet to a discharge outlet located on the marine vessel.

Abstract: A marine propulsion system is for propelling a marine vessel in water. The system comprises a marine vessel and an outboard motor that is coupled to the marine vessel. The outboard motor has a first inlet that receives intake air for combustion. A second inlet is located on the hull of the marine vessel and a conduit conveys the intake air from the second inlet on the marine vessel to the first inlet on the outboard motor. The system comprises an outboard motor that is coupled to a marine vessel, and that comprises an exhaust gas relief outlet that is located above the water when the outboard motor is at idle speed. A conduit conveys exhaust gas from the exhaust gas relief outlet to a discharge outlet located on the marine vessel.

Abstract: A position control system for a marine propulsion device senses an undesirable operating condition in the propulsion engine, such as low cooling water pressure at high speed or high engine temperature, to automatically lower the drive unit to a position in which the undesirable operating condition is likely to be alleviated. The system may include a logic timer circuit which will lower the drive unit for a short period of time, hold it in that position if the undesirable condition has been eliminated, or lower the drive unit further if the undesirable operating condition remains. The position control system may be incorporated into a conventional lift system, particularly a lift system used with a transom extension mounting assembly.

Abstract: A mounting assembly for an outboard motor includes a motor mount having a transom mounting bracket attachable to a boat transom and a motor supporting bracket spaced aft of and pivotally connected by upper and lower links with the transom mounting bracket to support an outboard motor wholly aft of the boat transom, and cylinder means for moving the motor supporting bracket relative to the transom mounting bracket to simultaneously move the outboard motor between raised and lowered positions in a vertical plane which extends parallel to the longitudinal dimension of a boat and to rotate the motor about a horizontal axis which extends perpendicular to the vertical plane. The movement of the outboard motor is provided by the motor mount being a quadrilateral structure wherein the lower link is shorter in length than the upper link and the motor supporting bracket is shorter in length than the transom mounting bracket.

Abstract: In a two cycle internal combustion engine (2), a turbulence generator (70) is provided by a freely rotating fan (72) in the fuel-air stream to the reed valves (16) which supply the fuel-air mixture into the crankcase chamber (8). The freely rotating fan (72) is driven by the fuel-air mixture flow and rotates to generate turbulence to provide more uniform distribution of the fuel-air mixture.

Abstract: A marine drive (2) is provided with an anti-ventilation plate (22) having a forward horizontal portion (24) and an aft portion (26) extending downwardly at an angle (28) to horizontal and noncoplanar with the forward portion (24). An adjustable anti-ventilation plate (30, 58) is also provided. The preferred form of the adjustable anti-ventilation plate is particularly simple and readily added to existing structure.

Abstract: A stern drive marine propulsion system (2) has an inboard engine (4) with an exhaust (6), an outboard drive unit (8) operatively coupled to the engine (4) and separated therefrom by a transom (10) having two exhaust passages (28 and 34) therethrough, and an exhaust control assembly (16) aft of the engine exhaust (6) and forward of the transom (10) and within the boat (12). The assembly (16) has an inlet (18) connected to the engine exhaust (6), and has first and second outlets (22 and 24) communicating with the respective exhaust passages (28 and 34) extending aft through the transom (10). A valve (26) in the assembly (16) selectively controls communication of the inlet (18) with the first outlet (22).

Abstract: An improved vane steering system for marine drives has the steering vane mounted in the skeg of the propulsion unit. With such a mounting location, the steering vane is submerged in the water in all driving positions of the propulsion unit.