Abstract: A steering system on a marine vessel includes at least one outboard drive configured to propel the marine vessel, a steering actuator configured to rotate the at least one outboard drive, at least one trim device coupled to the marine vessel and movable with respect to a hull of the marine vessel to adjust a running angle thereof, and at least one trim actuator. A control system configured to determine a desired roll angle and at least one of a desired turn rate and desired turn angle for the marine vessel based on a steering instruction and control the steering actuator to rotate the at least one outboard drive based on the desired turn rate and/or the desired turn angle and control the at least one trim actuator to move the at least one trim device based on the desired roll angle to effectuate the steering instruction.

Abstract: A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

Abstract: A stern drive is for propelling a marine vessel in water. The stern drive has an upper drive unit with a lower mounting surface; a lower gearcase coupled to the lower mounting surface and a trailing end surface that is angled relative to the lower mounting surface; and a propeller shaft extending forwardly from the lower gearcase and being configured to rotate a propeller for pulling the marine vessel in the water. The upper drive unit and the lower gearcase are configured such that when a forward side of the lower gearcase impacts an underwater obstruction, the lower gearcase is caused to pivot relative to the upper drive unit until the trailing end surface impacts the lower mounting surface, which thereby causes the lower gearcase to completely uncouple from the upper drive unit.

Abstract: A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

Abstract: A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

Abstract: A steering system on a marine vessel includes at least one propulsion device, a steering actuator that rotates the propulsion device to effectuate steering, at least one trim device moveable to adjust a running angle of the vessel, and a trim actuator configured to move the trim device so as to adjust the running angle. The system further includes a control system configured to determine a desired roll angle and at least one of a desired turn rate and a desired turn angle for the marine vessel based on a steering instructions. The control system then controls the steering actuator to the rotate the at least one propulsion device based on the desired turn rate and/or the desired turn angle, and to control the trim actuator to move the at least one trim device based on the desired roll angle so as to effectuate the steering instruction.

Abstract: A stern drive is for propelling a marine vessel in water. The stern drive has an upper drive unit with a lower mounting surface; a lower gearcase coupled to the lower mounting surface and a trailing end surface that is angled relative to the lower mounting surface; and a propeller shaft extending forwardly from the lower gearcase and being configured to rotate a propeller for pulling the marine vessel in the water. The upper drive unit and the lower gearcase are configured such that when a forward side of the lower gearcase impacts an underwater obstruction, the lower gearcase is caused to pivot relative to the upper drive unit until the trailing end surface impacts the lower mounting surface, which thereby causes the lower gearcase to completely uncouple from the upper drive unit.

Abstract: A marine propulsion device includes an engine, a driveshaft powered by the engine, a propulsor shaft coupled in torque-transmitting relationship with the driveshaft, and a propulsor coupled to the propulsor shaft and rotatable to produce a thrust. A housing supports the propulsor shaft therein. The housing has fore and aft skegs projecting from a bottom surface thereof.

Abstract: A stern drive is for propelling a marine vessel in water. The stern drive has an upper drive unit with a lower mounting surface; a lower gearcase coupled to the lower mounting surface and a trailing end surface that is angled relative to the lower mounting surface; and a propeller shaft extending forwardly from the lower gearcase and being configured to rotate a propeller for pulling the marine vessel in the water. The upper drive unit and the lower gearcase are configured such that when a forward side of the lower gearcase impacts an underwater obstruction, the lower gearcase is caused to pivot relative to the upper drive unit until the trailing end surface impacts the lower mounting surface, which thereby causes the lower gearcase to completely uncouple from the upper drive unit.

Abstract: A stern drive is for propelling a marine vessel in water. The stern drive has an upper drive unit with a lower mounting surface; a lower gearcase coupled to the lower mounting surface and a trailing end surface that is angled relative to the lower mounting surface; and a propeller shaft extending forwardly from the lower gearcase and being configured to rotate a propeller for pulling the marine vessel in the water. The upper drive unit and the lower gearcase are configured such that when a forward side of the lower gearcase impacts an underwater obstruction, the lower gearcase is caused to pivot relative to the upper drive unit until the trailing end surface impacts the lower mounting surface, which thereby causes the lower gearcase to completely uncouple from the upper drive unit.

Abstract: A lower unit for a marine propulsion device includes a gearcase housing defined along a longitudinal center axis between a fore end and an aft end. A propulsor shaft extends through the gearcase housing along the longitudinal axis. A driveshaft extends non-parallel to the propulsor shaft and rotates in a direction of rotation when powered by an engine. The driveshaft is coupled in torque-transmitting relationship with the propulsor shaft. A skeg projects from a bottom surface of the gearcase housing proximate at least the aft end thereof. The skeg or the gearcase housing is cambered such that a moment acting in a direction opposite the driveshaft's direction of rotation is induced on the skeg or the gearcase housing as the lower unit moves through water. A marine propulsion device is also disclosed.

Abstract: A marine drive has an internal combustion engine that rotates a propulsor shaft that is operatively coupled to a propulsor to impart a propulsive thrust in water. The marine drive has a gearcase housing having an upper portion above a lower portion, the lower portion supporting the propulsor shaft. An exhaust passage in the gearcase housing is configured to convey exhaust gas from the internal combustion engine. An exhaust outlet on the upper portion of the gearcase housing is configured to discharge the exhaust gas from the exhaust passage to the water. The exhaust outlet faces the propulsor so that the exhaust gas is discharged into the water and towards the propulsor so as to aerate the water encountered by the propulsor.

Abstract: A marine drive has an internal combustion engine that rotates a propulsor shaft that is operatively coupled to a propulsor to impart a propulsive thrust in water. The marine drive has a gearcase housing having an upper portion above a lower portion, the lower portion supporting the propulsor shaft. An exhaust passage in the gearcase housing is configured to convey exhaust gas from the internal combustion engine. An exhaust outlet on the upper portion of the gearcase housing is configured to discharge the exhaust gas from the exhaust passage to the water. The exhaust outlet faces the propulsor so that the exhaust gas is discharged into the water and towards the propulsor so as to aerate the water encountered by the propulsor.

Abstract: An outboard marine engine comprises an anti-ventilation plate; a torpedo housing that is disposed below the anti-ventilation plate; and a gearcase strut that extends from the anti-ventilation plate to the torpedo housing. The gearcase strut has a leading end, a trailing end, and opposing outer surfaces that extend from the leading end to the trailing end. A flow separator is on each outer surface. The flow separator is located closer to the trailing end than the leading end and causes flow of water across the gearcase strut to separate from the outer surface.

Abstract: A cooling system for a marine propulsion device provides a water flow directing device, which is generally annular in shape, which has a water inlet extending from it. The water flow directing device is attachable to a gear case of a marine propulsion device and is configured to conduct a flow of water from a water inlet to a passage formed within the marine propulsion device and connected in fluid communication with a water pump that causes the water to flow to a cooling system of an internal combustion engine. The water flow directing device is removably attachable to a seal carrier which, in turn, is attachable to a bearing carrier disposed within an internal cavity of the gear case. A secondary inlet is provided through a surface of the gear case and in fluid communication with an internal annular passage of the water flow directing device to encourage a flow of water into the cooling system when the marine propulsion device is operating at slow speeds or is stationary in a body of water.

Abstract: A cavity is provided at a bend in a cooling passage near a bore bridge region between cylinders of an internal combustion engine. The cavity can be provided with a downstream protuberance which induces a portion of the stream of coolant within the cooling passage to join a vortical flow of coolant within the cavity. An upstream protuberance can be provided to align a portion of the vortical flow within the cavity with the stream of coolant within the cooling passage in order to facilitate the return of the vortical flow back into the stream of coolant within the cooling passage.

Abstract: A hull of a boat, which is particularly intended for use with a jet pump propulsion system, is provided with two channels formed in the port and starboard surfaces of the hull and displaced from a keel line. Each channel comprises a forward edge that intersects the hull at an angle to define a continuous surface with a portion of the hull that is immediately forward of the channel. The channel intersects the transom of the boat at a rearward edge. Each channel has a pair of sidewalls which are contiguous with their associated generally planar surface of the channel. The sidewalls are generally parallel to a central vertical plane which extends from a bow of the boat to a transom of the boat and in which the keel line is disposed. Each pair of sidewalls are generally parallel to each other.