A marine engine has a powerhead, a crankcase and a crankshaft disposed in the crankcase. A cooling system has a cooling passage that conveys cooling water for cooling the crankcase, a pump that pumps the cooling water from a body of water in which the marine engine is operated through the cooling passage, and a valve that controls discharge of the cooling water from the cooling passage.

A marine engine has a powerhead, a crankcase and a crankshaft disposed in the crankcase. A cooling system has a cooling passage that conveys cooling water for cooling the crankcase, a pump that pumps the cooling water from a body of water in which the marine engine is operated through the cooling passage, and a valve that controls discharge of the cooling water from the cooling passage.

A cooling system for a boat includes at least one cooler located inside a hull of the boat and closed to the exterior of the hull. The cooler is configured for the exchange of thermal energy between a flow of coolant in the at least one cooler and a fluid flow outside of the hull via a hull wall positioned between the flow of coolant and the fluid flow. One or more coolant passages extend from the at least one cooler defining at least one coolant loop. The one or more coolant passages are configured to deliver the flow of coolant from the at least one cooler to one or more components located along the at least one coolant loop to cool the one or more components, and return the flow of coolant to the at least one cooler.

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 outboard motor has a powerhead that causes rotation of a driveshaft, a steering housing located below the powerhead, wherein the driveshaft extends from the powerhead into the steering housing; and a lower gearcase located below the steering housing and supporting a propeller shaft that is coupled to the driveshaft so that rotation of the driveshaft causes rotation of the propeller shaft. The lower gearcase is steerable about a steering axis with respect to the steering housing and powerhead.

An outboard motor has a powerhead that causes rotation of a driveshaft, a steering housing located below the powerhead, wherein the driveshaft extends from the powerhead into the steering housing; and a lower gearcase located below the steering housing and supporting a propeller shaft that is coupled to the driveshaft so that rotation of the driveshaft causes rotation of the propeller shaft. The lower gearcase is steerable about a steering axis with respect to the steering housing and powerhead.

A marine vessel propulsion device having a metal component in contact with water. The marine vessel propulsion device includes an anticorrosive anode made of a metal material that is less corrosion-resistant than the metal component, is electrically connected to the metal component, and is disposed in contact with the water contacting the metal component, a primary reference electrode isolated from the metal component and the anticorrosive anode, and disposed in contact with the water contacting the metal component, and a potentiometer that detects a potential difference of the metal component or the anticorrosive anode with respect to the primary reference electrode.

A marine outboard engine includes an internal combustion engine assembly that includes an internal combustion engine, a fuse assembly, a fuel filter, a spark plug, a gearcase including one of a propeller and an impeller, a swivel bracket, and a cowling. The cowling includes a service panel disposed on a first lateral side of the internal combustion engine assembly, and an affixed panel disposed on a second lateral side of the internal combustion engine assembly. The service and affixed panels define a split line therebetween and are removably attached to each other. The fuse assembly, the fuel filter, and the spark plug are mounted to one of the first lateral side and the affixed panel proximate to the split line and are at least in part accessible from the first lateral side when the service panel is detached and removed from the affixed panel.

A marine outboard engine includes an internal combustion engine assembly that includes an internal combustion engine, a fuse assembly, a fuel filter, a spark plug, a gearcase including one of a propeller and an impeller, a swivel bracket, and a cowling. The cowling includes a service panel disposed on a first lateral side of the internal combustion engine assembly, and an affixed panel disposed on a second lateral side of the internal combustion engine assembly. The service and affixed panels define a split line therebetween and are removably attached to each other. The fuse assembly, the fuel filter, and the spark plug are mounted to one of the first lateral side and the affixed panel proximate to the split line and are at least in part accessible from the first lateral side when the service panel is detached and removed from the affixed panel.

A system for controlling a thermal signature of a boat is disclosed. The system includes a fluid compartment adjacent to an external wall of the boat. The fluid compartment is disposed between a heat source in a hull cavity of the boat and the external wall of the boat such that heat energy released from the heat source is transferred to a fluid in the fluid compartment. A fluid mover moves a first volume of the fluid out of the fluid compartment and replaces at least a portion of the first volume with a second volume of fluid, wherein the second volume of fluid has a different temperature than the first volume of fluid before entering the fluid compartment.