A marine reduction gear makes it possible to reduce the installation space of an electrical rotating machine. A marine reduction gear includes: an input shaft coupled to an output shaft of an engine; an output shaft coupled to a propeller shaft that rotates a screw propeller; a gearbox accommodating an input gear provided on the input shaft and an output gear provided on the output shaft, the gearbox supporting a first bearing that supports the output shaft in a rotatable manner; and an electrical rotating machine including: a central shaft that rotates together with the output shaft; a rotor fixed to the central shaft; and a stator surrounding the rotor. The gearbox supports the stator and a second bearing that supports the central shaft of the electrical rotating machine in a rotatable manner.

A marine reduction gear makes it possible to reduce the installation space of an electrical rotating machine. A marine reduction gear includes: an input shaft coupled to an output shaft of an engine; an output shaft coupled to a propeller shaft that rotates a screw propeller; a gearbox accommodating an input gear provided on the input shaft and an output gear provided on the output shaft, the gearbox supporting a first bearing that supports the output shaft in a rotatable manner; and an electrical rotating machine including: a central shaft that rotates together with the output shaft; a rotor fixed to the central shaft; and a stator surrounding the rotor. The gearbox supports the stator and a second bearing that supports the central shaft of the electrical rotating machine in a rotatable manner.

A navigation method for a ship which includes: a plurality of main generators that feed power to navigation equipment used in normal navigation and appliances for the living quarters provided within a ship body; and an emergency generator that feeds power to emergency equipment in case of fire or flood. The navigation method includes: an emergency power feeding step for feeding power to the emergency equipment using the emergency generator when at least one of the plurality of main generators is disabled due to fire or flood; and a return-to-port power feeding step for feeding power to return-to-port equipment, required for navigation for returning to port, using the main generators and the emergency generator after the fire or flood has subsided.

A navigation method for a ship which includes: a plurality of main generators that feed power to navigation equipment used in normal navigation and appliances for the living quarters provided within a ship body; and an emergency generator that feeds power to emergency equipment in case of fire or flood. The navigation method includes: an emergency power feeding step for feeding power to the emergency equipment using the emergency generator when at least one of the plurality of main generators is disabled due to fire or flood; and a return-to-port power feeding step for feeding power to return-to-port equipment, required for navigation for returning to port, using the main generators and the emergency generator after the fire or flood has subsided.

A heat exchanger is for use in an energy recovery system to be mounted on a vessel including an engine, a supercharger and an economizer, the heat exchanger including: a first heat section for heating a working medium by supercharged air from the supercharger; a second heat section for heating the supercharged air by steam generated by the economizer before the supercharged air flows into the first heat section; and a third heat section for heating the working medium having been heated in the first section by the supercharged air which is to be heated in the second section.

A heat exchanger is for use in an energy recovery system to be mounted on a vessel including an engine, a supercharger and an economizer, the heat exchanger including: a first heat section for heating a working medium by supercharged air from the supercharger; a second heat section for heating the supercharged air by steam generated by the economizer before the supercharged air flows into the first heat section; and a third heat section for heating the working medium having been heated in the first section by the supercharged air which is to be heated in the second section.

A buoyant vessel having a hull and a drive system mounted to the hull, the system having a rectifier, a generator, an AC bus in communication with shore power or a charging system and the rectifier, a DC bus in communication with the rectifier, at least one energy storage system, an inverter, a prime mover, a load regenerating device, and a control and monitor system which has predefined specifications for at least one of: storage units of at least one energy storage system; stored therein and wherein the control and monitor system is adapted to: automatically control the DC/DC converters, relieve a current draw from one or more storage units, provide charging current, and automatically draw power and redirect energy.

A buoyant vessel having a hull and a drive system mounted to the hull, the system having a rectifier, a generator, an AC bus in communication with shore power or a charging system and the rectifier, a DC bus in communication with the rectifier, at least one energy storage system, an inverter, a prime mover, a load regenerating device, and a control and monitor system which has predefined specifications for at least one of: storage units of at least one energy storage system; stored therein and wherein the control and monitor system is adapted to: automatically control the DC/DC converters, relieve a current draw from one or more storage units, provide charging current, and automatically draw power and redirect energy.

A marine propulsion system for a marine vessel includes a marine propulsion device, a plurality of power storage devices, and a charge distribution circuit. The marine propulsion device includes an engine and an alternator driven by the engine to generate a charge current. The plurality of power storage devices includes at least a first power storage device and a second power storage device, wherein each power storage device is configured to receive current from the alternator. The charge distribution circuit is positioned between the alternator and the plurality of power storage devices and includes an isolator configured to isolate the first power storage device from the second power storage device, a charge sensor configured to sense a charge level of the first power storage device, and a relay configured to connect and disconnect the second power storage device to/from the alternator based on the sensed charge level.

A vessel power supply system for a vessel including a propulsion device that includes an engine and a generator driven by the engine to generate electricity, includes a first battery that supplies power to the propulsion device, a second battery that supplies power to accessories of the vessel, a first open circuit voltage sensor that detects an open circuit voltage of the first battery, a second open circuit voltage sensor that detects an open circuit voltage of the second battery, and a switch that is turned on/off to open and close a current path between the first battery and the second battery.