An outboard motor includes an engine, a propeller shaft that rotates together with a propeller and extends in a forward-rearward direction, and a lower case that houses the propeller shaft. The lower case includes a front case and a rear case separate from the front case and positioned rearward of the front case, and the front case and the rear case are assembled to each other.

Dew condensation in a housing of an inverter device can be prevented. The inverter device includes: a housing accommodating a power electronic element and an electrolytic capacitor; an opening formed in the housing; a thermal insulator disposed along a periphery of the opening; and a water jacket having a body portion, and a flow-in pipe and a discharge pipe for cooling water, the water jacket being disposed such that a first surface of the body portion closes the opening from an outside of the housing, with the thermal insulator interposed therebetween. The power electronic element is mounted on the first surface of the body portion, and the electrolytic capacitor is mounted in the housing so as to be in contact with an inner surface of the housing.

An improved boat and drive assembly intended for a boat used in a primary shallow water environment has a hull with an integrated closed internal engine heat exchanger and a drive assembly that includes a ring-within-a-ring steering mechanism and an obstacle resistant shoe plate. Stabilizer fins positioned above the shoe plate at a position forward of the spinning propeller allow air and water to exit from the rear of the stabilizer fins away from the spinning propeller. The heat exchanger assembly may include an axillary cooling tank and open heat dissipation system having a raw water reservoir continuously filled with raw water drawn directly from the waterway on which the boat is propelled to enhance the cooling capacity of the integrated internal engine heat exchanger.

An improved boat and drive assembly intended for a boat used in a primary shallow water environment has a hull with an integrated closed internal engine heat exchanger and a drive assembly that includes a ring-within-a-ring steering mechanism and an obstacle resistant shoe plate. Stabilizer fins positioned above the shoe plate at a position forward of the spinning propeller allow air and water to exit from the rear of the stabilizer fins away from the spinning propeller. The heat exchanger assembly may include an axillary cooling tank and open heat dissipation system having a raw water reservoir continuously filled with raw water drawn directly from the waterway on which the boat is propelled to enhance the cooling capacity of the integrated internal engine heat exchanger.

An outboard motor includes an engine, a propeller shaft, a propeller attached to the propeller shaft, a transmission to transmit rotation of the engine to the propeller shaft, an upper accommodation body accommodating at least a portion of the engine, a lower accommodation body accommodating at least a portion of the propeller shaft, and a steering to cause the lower accommodation body to rotate about a steering axis with respect to the upper accommodation body. The upper accommodation body includes an upper coolant channel. The lower accommodation body includes a lower coolant channel including a coolant intake port. A communication area between the upper and lower coolant channels is changeable according to a rudder angle of the steering.

A marine drive is for propelling a marine vessel. The marine drive includes: an engine; an exhaust manifold that conveys exhaust gas from the engine; a cooling jacket on the exhaust manifold, wherein a cooling passage is defined between the cooling jacket and the exhaust manifold; a cooling pump that pumps cooling fluid through the cooling passage so as to cool the exhaust manifold and the exhaust gas; a power steering actuator configured to steer the marine drive relative to the marine vessel; a power steering pump that pumps power steering fluid from a power steering reservoir to the power steering actuator; and a power steering cooler on the exhaust manifold and configured such that the power steering fluid is cooled by the cooling fluid in the cooling passage. In some examples the marine drive is configured for use in an outboard motor.

A marine drive is for propelling a marine vessel. The marine drive includes: an engine; an exhaust manifold that conveys exhaust gas from the engine; a cooling jacket on the exhaust manifold, wherein a cooling passage is defined between the cooling jacket and the exhaust manifold; a cooling pump that pumps cooling fluid through the cooling passage so as to cool the exhaust manifold and the exhaust gas; a power steering actuator configured to steer the marine drive relative to the marine vessel; a power steering pump that pumps power steering fluid from a power steering reservoir to the power steering actuator; and a power steering cooler on the exhaust manifold and configured such that the power steering fluid is cooled by the cooling fluid in the cooling passage. In some examples the marine drive is configured for use in an outboard motor.

An outboard motor includes an engine, an electric motor, a propeller that rotates due to a driving force from the engine and a driving force from the electric motor, and an anti-cavitation plate disposed above the propeller. At least a portion of the electric motor is disposed above the anti-cavitation plate and below a waterline of an outboard motor body.

An outboard motor includes an engine, an electric motor, a propeller that rotates due to a driving force from the engine and a driving force from the electric motor, and an anti-cavitation plate disposed above the propeller. At least a portion of the electric motor is disposed above the anti-cavitation plate and below a waterline of an outboard motor body.

A marine engine has first and second banks of piston-cylinders, and first and second cooling water passages that convey cooling water in parallel alongside the first and second banks of piston-cylinders, respectively. A cooling water pump pumps the cooling water through the first and second cooling water passages. A first temperature-responsive valve is configured to discharge the cooling water from both of the first and second cooling water passages when the cooling water reaches a first temperature threshold. A second temperature-responsive valve is configured to discharge the cooling water from both of the first and second cooling water passages when the cooling water reaches a second temperature threshold that is greater than the first temperature threshold.