A marine drive unit for a boat includes a cooling compartment arranged in a drive unit body. The cooling compartment forms part of a closed cooling circuit, where the cooling circuit is arranged to cool propulsion components of the boat, where the cooling compartment comprises an inlet opening, an inlet channel, a lower end, an outlet channel and an outlet opening, where the inlet channel forms a first flow path for a cooling fluid from the inlet opening to the lower end of the cooling compartment. The outlet channel forms a second flow path for the cooling fluid from the lower end of the cooling compartment to the outlet opening, thereby allowing heat from the cooling fluid to dissipate through the outer wall of the drive unit.

A system for draining a cooling system of a power generation system on a marine vessel includes a pump in fluid communication with the cooling system, the pump actively removing cooling water from the cooling system. An outlet drain discharges the cooling water. A controller starts the pump in response to an operator command to stop a prime mover of the marine power generation system and/or a speed of the prime mover being below a threshold speed. In one example, a temperature sensor determines a temperature of the cooling water in the cooling system, and the controller stops the pump in response to the temperature of the cooling water exceeding a threshold temperature. In another example, a sensor determines a pressure and/or a level of the cooling water in the cooling system, and the controller stops the pump in response to the pressure and/or the level of the cooling water dropping below a threshold pressure or a threshold level, respectively.

A fuel cell ship includes a fuel cell compartment in which a fuel cell is installed, a tank compartment in which a fuel tank is installed, a fuel supply pipe through which fuel is supplied from the fuel tank to the fuel cell, and a control unit. The fuel supply pipe includes at least two shutoff valves. Fuel gas detectors that detect a fuel gas being in a gaseous state of the fuel are each installed in the compartments. If at least one of the fuel gas detectors detects that a concentration of the fuel gas is equal to or greater than a predetermined standard value, the control unit controls to close a shutoff valve in a compartment out of the tank compartment and the fuel cell compartment, where the fuel gas detector having detected the concentration equal to or greater than the standard value is installed.

A fuel cell ship includes a fuel cell compartment in which a fuel cell is installed, a tank compartment in which a fuel tank is installed, a fuel supply pipe through which fuel is supplied from the fuel tank to the fuel cell, and a control unit. The fuel supply pipe includes at least two shutoff valves. Fuel gas detectors that detect a fuel gas being in a gaseous state of the fuel are each installed in the compartments. If at least one of the fuel gas detectors detects that a concentration of the fuel gas is equal to or greater than a predetermined standard value, the control unit controls to close a shutoff valve in a compartment out of the tank compartment and the fuel cell compartment, where the fuel gas detector having detected the concentration equal to or greater than the standard value is installed.

An exemplary fuel cell ship is a fuel cell ship for propelling a hull by using electric power supplied from a fuel cell that generates electric power through an electrochemical reaction of fuel, and includes a tank compartment installed therein with a fuel tank that stores the fuel. The tank compartment is provided below a deck of the hull and provided separately from other compartments.

An exemplary fuel cell ship is a fuel cell ship for propelling a hull by using electric power supplied from a fuel cell that generates electric power through an electrochemical reaction of fuel, and includes a tank compartment installed therein with a fuel tank that stores the fuel. The tank compartment is provided below a deck of the hull and provided separately from other compartments.

A watercraft and a marine engine assembly for mounting to a watercraft are disclosed. The marine engine assembly includes an engine unit including: an engine unit housing being sealed such that water in which the engine unit housing is immersed is impeded from entering the engine unit housing; an engine in the housing; and an air intake assembly in the engine unit housing which forms a conduit between an exterior of the engine unit housing and the engine, the air intake assembly defining an inlet fluidly communicating with exterior air, the engine unit housing defining at least one aperture aligned with the inlet, the air intake assembly defining at least one outlet fluidly connected with the engine intake, the air intake assembly being sealed such that surrounding fluids within the engine unit housing are impeded from entering the air intake assembly; and a propulsion device operatively connected to the engine.

A watercraft and a marine engine assembly for mounting to a watercraft are disclosed. The marine engine assembly includes an engine unit including: an engine unit housing being sealed such that water in which the engine unit housing is immersed is impeded from entering the engine unit housing; an engine in the housing; and an air intake assembly in the engine unit housing which forms a conduit between an exterior of the engine unit housing and the engine, the air intake assembly defining an inlet fluidly communicating with exterior air, the engine unit housing defining at least one aperture aligned with the inlet, the air intake assembly defining at least one outlet fluidly connected with the engine intake, the air intake assembly being sealed such that surrounding fluids within the engine unit housing are impeded from entering the air intake assembly; and a propulsion device operatively connected to the engine.

A marine propulsion unit includes a stern drive mounted to a transom. The stern drive comprises an upper unit enclosed in a stern drive housing and a lower unit enclosed in a gearbox housing; wherein the gearbox housing contains a gearbox arranged to drive at least one propeller. The propulsion unit further comprises at least two electric motors arranged in the stern drive housing, which electric motors are mounted with vertical output shafts; a planetary gear set arranged between the at least two electric motors and the gearbox, and a vertical shaft that is attached to a ring gear of the planetary gear set at its upper end and is connected to the gearbox at its lower end; wherein the output shaft of each electric motor is connected to a planetary gear arranged in the planetary gear set to drive the ring gear and the vertical shaft connected to the gearbox.

The present invention relates to a gas treatment system and a ship including the same. The gas treatment system treats liquefied gas as heavier hydrocarbons or ammonia. The gas treatment system includes: a fuel tank storing liquefied gas as a fuel to be supplied to a propulsion engine of a ship; a liquefied gas supply line supplying the liquefied gas of the fuel tank in a liquid phase to the propulsion engine, the liquefied gas supply line having a high pressure pump provided thereon; a reliquefaction apparatus liquefying boil-off gas generated in a cargo tank storing liquefied gas; and a liquefied gas collection line collecting the liquid liquefied gas discharged from the propulsion engine upstream of the high pressure pump. The reliquefaction apparatus transfers the liquefied boil-off gas to the fuel tank, thereby allowing the liquefied boil-off gas to be supplied to the propulsion engine by the high pressure pump.