A marine engine includes a cylinder block having first and second banks of cylinders disposed along a longitudinal axis and extending transversely relative to each other in a V-shape so as to define a valley there between, and first and second exhaust logs in which exhaust gas from the first and second banks of cylinders are collected and conveyed. An exhaust manifold is located in the V-shape and configured to merge said exhaust gases from the first and second exhaust logs and to convey said exhaust gases. The exhaust manifold has a first inlet port that receives substantially all said exhaust gas from the first exhaust log and a second exhaust inlet port that receives substantially all said exhaust gas from the second exhaust log. The first and second inlet ports are longitudinally offset relative to each other.

An axial flux propulsion system for an electric boat that includes interconnecting subsystems including a mounting system, a traction system, a transmission system, an electrical power distribution system, a control system, and a fluid management system, among other boat systems. The traction system typically is an axial flux motor/generator. Various embodiment of the axial flux propulsion system may include a stern drive embodiment and a jet drive embodiment. Portions of the axial flux propulsion system may be both inboard and outboard. A control system may control the operation of the various boat systems including the axial flux motor/generator, and as a result, control the overall operation of the boat.

A marine outboard motor for a marine vessel. The marine outboard motor includes: a housing comprising a chamber and at least one inlet arranged to be submerged, in use, into a body of water in which the marine outboard motor is operated, in order to draw water into the chamber; an engine assembly comprising an internal combustion engine; a drive shaft positioned in the housing, wherein the drive shaft is coupled to the internal combustion engine to drive a propulsion arrangement; a cooling system for cooling the internal combustion engine, the cooling system configured convey drawn water along a coolant flow path through the housing to deliver the drawn water to the internal combustion engine; and a sleeve by which the drive shaft is sealed from drawn water within the housing, the sleeve having first and second ends, wherein at least a part of the drive shaft is encased within the sleeve.

A marine outboard motor for a marine vessel. The marine outboard motor includes: a housing comprising a chamber and at least one inlet arranged to be submerged, in use, into a body of water in which the marine outboard motor is operated, in order to draw water into the chamber; an engine assembly comprising an internal combustion engine; a drive shaft positioned in the housing, wherein the drive shaft is coupled to the internal combustion engine to drive a propulsion arrangement; a cooling system for cooling the internal combustion engine, the cooling system configured convey drawn water along a coolant flow path through the housing to deliver the drawn water to the internal combustion engine; and a sleeve by which the drive shaft is sealed from drawn water within the housing, the sleeve having first and second ends, wherein at least a part of the drive shaft is encased within the sleeve.

An outboard motor includes a first cooling water passage through which first cooling water including water from outside an outboard motor body passes to cool a first cooling target including at least one of an electrical component other than an engine and fuel in a fuel tank, and a first pump that is an electric pump that pumps the first cooling water from outside of the outboard motor body and flows the first cooling water into the first cooling water passage.

An outboard motor includes a first cooling water passage through which first cooling water including water from outside an outboard motor body passes to cool a first cooling target including at least one of an electrical component other than an engine and fuel in a fuel tank, and a first pump that is an electric pump that pumps the first cooling water from outside of the outboard motor body and flows the first cooling water into the first cooling water passage.

An exhaust gas purification structure of an outboard motor includes an exhaust gas pipe that has an exhaust gas passage through which exhaust gas of an engine can flow; and a catalyst that is provided in the exhaust gas passage and purifies the exhaust gas by allowing the exhaust gas to pass through the inside thereof. The exhaust gas pipe includes a coolant flow passage allowing a coolant that cools the exhaust gas to flow therethrough. An exhaust gas bypass passage allowing the exhaust gas to flow without passing through the catalyst is formed between the catalyst and an inner surface of the exhaust gas pipe forming the exhaust gas passage.

A marine vessel power supply system for a marine vessel including an electric motor to rotate a propeller includes an inverter to supply electric power to the electric motor, a battery to supply electric power to the inverter, and an electronic control unit configured or programmed to control the inverter. The inverter includes an inverter circuit to convert DC electric power supplied from the battery to AC electric power, a voltage detector to detect the voltage in a wiring between the battery and the inverter circuit, and a microcomputer configured or programmed to communicate with the electronic control unit and to control the inverter circuit according to a command supplied from the electronic control unit. The electronic control unit calculates an SOC estimate indicative of an estimated state-of-charge value of the battery based on a value of the voltage detected by the voltage detector and acquired from the microcomputer.

A marine vessel power supply system for a marine vessel including an electric motor to rotate a propeller includes an inverter to supply electric power to the electric motor, a battery to supply electric power to the inverter, and an electronic control unit configured or programmed to control the inverter. The inverter includes an inverter circuit to convert DC electric power supplied from the battery to AC electric power, a voltage detector to detect the voltage in a wiring between the battery and the inverter circuit, and a microcomputer configured or programmed to communicate with the electronic control unit and to control the inverter circuit according to a command supplied from the electronic control unit. The electronic control unit calculates an SOC estimate indicative of an estimated state-of-charge value of the battery based on a value of the voltage detected by the voltage detector and acquired from the microcomputer.

This oil case of an outboard motor is provided below an engine and stores lubricating oil of the engine. In this method for manufacturing the oil case, the oil case is manufactured so as to comprise: an oil chamber; an introduction path that guides upward cooling supply water drawn in from outside the outboard motor; a delivery path that guides downward cooling discharge water that has cooled the engine; a main exhaust path that guides exhaust gas of the engine downward; and a sub exhaust path that guides exhaust gas during low-speed rotation of the engine. The oil chamber, the introduction path, the delivery path, the main exhaust path and the sub exhaust path form an integral structure.