An outboard motor equipped with a four-stroke engine and provided with a catalyst installation structure, in which an exhaust passage is connected to the exhaust ports of the plurality of the cylinders to lead the exhaust gas out of the engine is provided with a catalyst storage chamber configured to store a catalytic converter for cleaning up the exhaust gas, the exhaust passage being integrally formed to the cylinder block, and the catalytic converter is mounted to the catalyst storage chamber by being inserted from a lower side thereof in such a manner as that at least one side end portion thereof is fitted to the catalyst storage chamber to permit expansion of the catalytic converter in an axial direction thereof.

A marine propulsion device includes an engine, an exhaust pipe to allow exhaust gas of the engine to pass through the exhaust pipe, and a cooling water supply passage to supply cooling water for the engine into the exhaust pipe toward a downstream side in a flow direction of the exhaust gas and cause the cooling water to flow circumferentially along an inner peripheral surface of the exhaust pipe.

A vessel propulsion apparatus includes an engine and a propulsion unit to be driven by the engine. The engine includes cylinders arranged in series, exhaust ports respectively connected to combustion chambers of the cylinders and curved in a predetermined downstream direction to allow exhaust gases to flow out from the combustion chambers, and a collecting exhaust pipe. The collecting exhaust pipe is integral with the exhaust ports, and extends in the downstream direction to allow exhaust gases in the exhaust ports to flow in the downstream direction. At least one of a plurality of connector portions that individually connect the exhaust ports to the collecting exhaust pipe includes a concave portion at an inner surface thereof.

An outboard-motor closed-loop cooler system apparatus providing a retrofit substitute for the midsection and the lower unit of a standard outboard motor, having a substitute closed-loop cooling system with an exterior heat exchanger, a substitute oil reservoir, a substitute exhaust system, and a substitute propulsion system, allowing an existing standard outboard-motor powerhead to be used in conditions not conducive to standard open-loop water cooling, such as shallow-water, muddy-water, obstructed-water, seawater, or corrosive-water conditions.

An elongated exhaust conduit comprises a first end receiving hot exhaust gas from a marine engine and a second end discharging the exhaust gas. An elongated cooling water jacket extends adjacent to the exhaust conduit. The cooling water jacket conveys the raw cooling water adjacent to the exhaust conduit to thereby cool the exhaust conduit and warm the raw cooling water therein and discharges the warmed cooling water to cool the marine engine. The cooling water jacket comprises first and second channels that are separate from each other. The cooling water is oriented in a helical flow around the exhaust conduit.

A marine drive comprising a powerhead that causes rotation of a driveshaft, a gearcase that supports a propulsor for propelling the marine drive in a body of water, a steering housing disposed between the powerhead and the gearcase, wherein the driveshaft or an extension thereof extends through the steering housing is operatively coupled to the propulsor, and a steering mechanism configured to steer the gearcase about a steering axis relative to the steering housing. The gearcase and steering housing are connected at a steering joint through which at least one of cooling water from the body of water is conveyed to the powerhead throughout steering movement of the gearcase and exhaust from the powerhead is conveyed to the body of water throughout steering movement of the gearcase.

An outboard motor includes a first pipe made of metal to allow high-pressure hydrogen to be supplied therethrough to a first fuel injector, a second pipe made of metal to allow the high-pressure hydrogen to be supplied therethrough to a second fuel injector, and a flexible pipe made of bendable metal to connect the first pipe to the second pipe so as to allow the high-pressure hydrogen to flow therethrough to both the first pipe and the second pipe.

An embodiment of an exhaust handling system for a marine vessel includes a cap connected to a top end portion of an exhaust stack of the marine vessel to form an enclosure at least partially surrounding an outlet of an exhaust pipe extending through the exhaust stack. In addition, the exhaust handling system includes a collection pipe in fluid communication with the cap such that the collection pipe is to receive exhaust from the enclosure, and a coupling connected to the collection pipe that is to connect to an exhaust cleaning assembly. The exhaust cleaning system includes a tank to receive the exhaust. The cap at least partially defines a first flow path for the exhaust that extends from the enclosure to the atmosphere. The collection pipe at least partially defines a second flow path for the exhaust that extends from the enclosure to the coupling via the collection pipe.

An outboard motor includes a first case accommodating an engine and an upper housing below the first case. At least a portion of an exhaust passage is in the upper housing and extends downward from the engine. A second case is below the upper housing. The second case includes a torpedo portion, an exhaust inlet, an exhaust outlet, and an exhaust chamber. The torpedo portion includes an internal space and a rear end. A propeller shaft is in the internal space of the torpedo portion. The rear end of the torpedo portion is forward of at least a portion of the exhaust passage as seen in a side view. The exhaust passage is connected to the exhaust inlet. The exhaust outlet communicates with the internal space of the torpedo section. The exhaust chamber communicates the exhaust inlet with the exhaust outlet.

An embodiment of an exhaust handling system for a marine vessel includes a cap connected to a top end portion of an exhaust stack of the marine vessel to form an enclosure at least partially surrounding an outlet of an exhaust pipe extending through the exhaust stack. In addition, the exhaust handling system includes a collection pipe in fluid communication with the cap such that the collection pipe is to receive exhaust from the enclosure, and a coupling connected to the collection pipe that is to connect to an exhaust cleaning assembly. The exhaust cleaning system includes a tank to receive the exhaust. The cap at least partially defines a first flow path for the exhaust that extends from the enclosure to the atmosphere. The collection pipe at least partially defines a second flow path for the exhaust that extends from the enclosure to the coupling via the collection pipe.