An outboard engine assembly has an engine unit including an engine unit housing, an internal combustion engine disposed in the engine unit housing, the engine defining at least one combustion chamber, an exhaust system fluidly communicating with the at least one combustion chamber for supplying exhaust gases from the at least one combustion chamber to an exterior of the outboard engine assembly, a gearcase connected to the engine unit housing, a control module connected to the engine for controlling at least one operating parameter of the outboard engine assembly, and a water sensor disposed at least in part in the exhaust system for detecting presence of water in the exhaust system, the water sensor being in communication with the control module, and a propulsion device operatively connected to the engine.

An outboard motor is provided with an upper separator disposed on the lower side of an oil case for storing a lubricating oil of an engine, and an extension case which is separably connected on the lower side of the upper separator. The upper separator has a central exhaust passage through which exhaust gas flows, and a cooling water flow part through which cooling water flows on the outside of the central exhaust passage, the central exhaust passage and the cooling water flow part forming an integrated structure. The exhaust gas and the cooling water are caused to mix in the extension case.

The cooling device for a power source for a ship propulsion device that pumps up cooling water, from which foreign matters with sizes that cause clogging of a cooling water route have been removed, supplies the cooling water to a cooling water passage (30), and discharges the cooling water to outside after cooling a power source (10) includes: a cartridge-type filtration device (40, 73) that is provided at a midpoint of a first water passage (36, 71) in the cooling water route and incorporates a filter (45, 46) for filtrating foreign matters remaining in the cooling water; and a second water passage (38, 72) that is branched from the first water passage and adapted such that a valve member (53) is opened to cause the cooling water to flow in a case in which clogging occurs in the filter.

A marine drive is configured to propel a marine vessel in a body of water. The marine drive has an engine; a primary exhaust conduit receiving exhaust gases from the engine and discharging the exhaust gases to a primary exhaust outlet discharging the exhaust gases to the body of water; an idle relief exhaust outlet discharging exhaust gases to atmosphere, above the body of water; a primary idle relief muffler receiving exhaust gases from the primary exhaust conduit; a secondary idle relief muffler receiving exhaust gases from the primary idle relief muffler; and a tertiary idle relief muffler configured to receive exhaust gases from the secondary idle relief muffler and discharges exhaust gases to atmosphere via the idle relief exhaust outlet.

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 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.

A cooling structure for an outboard motor comprises an oil case which has an oil chamber for storing lubricant oil for an engine. Said cooling structure further comprises: a main exhaust gas passage which guides exhaust gas to a lower side; a cooling water outbound path which guides cooling supply water taken from outside the outboard motor to an upper side, and cools the periphery of the main exhaust gas passage in the oil case by means of the cooling supply water; a cooling water inbound path which guides cooling discharge water that has cooled the engine to the lower side and cools the oil chamber by means of said cooling discharge water; and a mixed fluid passage which, on a side below the oil case, cools the exhaust gas by mixing the exhaust gas and the cooling discharge water.

An exhaust system is for a marine propulsion device having an internal combustion engine. A catalyst housing has a housing inlet end that receives an exhaust gas flow from the internal combustion engine into the catalyst housing and an opposite, housing outlet end that discharges the exhaust flow out of the catalyst housing. A catalyst is disposed in the catalyst housing. The catalyst has a catalyst inlet end that receives the exhaust gas flow and an opposite, catalyst outlet end that discharges the exhaust gas flow. A catalyst mantel is on an outer periphery of the catalyst. The catalyst mantel has a mantel inlet end and an opposite, mantel outlet end. A radial flange is on at least one of the mantel outlet end and mantel inlet end. A connector mates with an inner diameter of the catalyst housing. The radially extending flange of the catalyst mantel is axially sandwiched between the connector and a radially inner shoulder of the catalyst housing.

An outboard motor includes a catalyst housing passage disposed inside the V-shaped line, a cooling water passage including at least a portion disposed at a periphery of a catalyst and that guides cooling water that cools an exhaust passage and a vent hole disposed higher than the catalyst and that connects the interior of the cooling water passage to the exterior of the cooling water passage.

An outboard motor is provided with an upper separator disposed on the lower side of an oil case for storing a lubricating oil of an engine, and an extension case which is separably connected on the lower side of the upper separator. The upper separator has a central exhaust passage through which exhaust gas flows, and a cooling water flow part through which cooling water flows on the outside of the central exhaust passage, the central exhaust passage and the cooling water flow part forming an integrated structure. The exhaust gas and the cooling water are caused to mix in the extension case.