An exhaust manifold is for an internal combustion engine on an outboard marine engine that is configured to power a propulsor to provide a thrust in a longitudinal direction. The exhaust manifold comprises an exhaust runner that transversely and longitudinally rearwardly conveys the exhaust gas from the internal combustion engine, an exhaust log that vertically upwardly conveys the exhaust gas from the exhaust runner, and an exhaust elbow that conveys the exhaust gas from the exhaust log vertically upwardly, longitudinally forwardly, and then vertically downwardly.

An exhaust manifold is for an internal combustion engine on an outboard marine engine that is configured to power a propulsor to provide a thrust in a longitudinal direction. The exhaust manifold comprises an exhaust runner that transversely and longitudinally rearwardly conveys the exhaust gas from the internal combustion engine, an exhaust log that vertically upwardly conveys the exhaust gas from the exhaust runner, and an exhaust elbow that conveys the exhaust gas from the exhaust log vertically upwardly, longitudinally forwardly, and then vertically downwardly.

An outboard motor includes an engine, a propeller shaft that rotates together with a propeller and extends in a forward-rearward direction, and a lower case that houses the propeller shaft. The lower case includes a front case and a rear case separate from the front case and positioned rearward of the front case, and the front case and the rear case are assembled to each other.

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.

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.

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 filtration device (40, 40A, 40B) provided in the cooling water route to filtrate foreign matters remaining in the cooling water, and the filtration device is of a cartridge type that incorporates a filter (45, 72) for filtration disposed in a main water passage (P1) and a valve member (46, 66) configured to open and close a bypass water passage (P2) and that is configured such that in a case in which clogging occurs in the filter, the valve member opens to cause the cooling water to flow via the bypass water passage.

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 filtration device (40, 40A, 40B) provided in the cooling water route to filtrate foreign matters remaining in the cooling water, and the filtration device is of a cartridge type that incorporates a filter (45, 72) for filtration disposed in a main water passage (P1) and a valve member (46, 66) configured to open and close a bypass water passage (P2) and that is configured such that in a case in which clogging occurs in the filter, the valve member opens to cause the cooling water to flow via the bypass water passage.

Provided herein is a marine propulsion apparatus including a prime mover having a drive shaft, a cowling enclosing the prime mover, first and second struts affixed to the cowling, where each of the struts have a leading portion, an interior belt void, and a trailing portion. The apparatus further includes a lower unit coupled to the distal ends of the struts, a sprocket rotatably disposed within the lower unit, a shaft rotatably coupled to the sprocket, a belt rotatably coupling the drive shaft to the sprocket, such that a first portion of the belt is disposed within the interior belt void of the first strut and a second portion of the belt is disposed within the interior belt void of the second strut. The apparatus further includes a thermal circuit (having a heat transfer fluid) extending from the cowling, through each of the struts, and into the lower unit.

Provided herein is a marine propulsion apparatus including a prime mover having a drive shaft, a cowling enclosing the prime mover, first and second struts affixed to the cowling, where each of the struts have a leading portion, an interior belt void, and a trailing portion. The apparatus further includes a lower unit coupled to the distal ends of the struts, a sprocket rotatably disposed within the lower unit, a shaft rotatably coupled to the sprocket, a belt rotatably coupling the drive shaft to the sprocket, such that a first portion of the belt is disposed within the interior belt void of the first strut and a second portion of the belt is disposed within the interior belt void of the second strut. The apparatus further includes a thermal circuit (having a heat transfer fluid) extending from the cowling, through each of the struts, and into the lower unit.

An outboard motor includes: a driveshaft housing configured to accommodate a driveshaft; and a gear case bulging laterally below the driveshaft housing and configured to accommodate a gear device, wherein an inside of the driveshaft housing communicates with an inside of the gear case, an introduction port for introducing lubricating oil into the gear case is opened on the driveshaft housing, and a confirmation port for causing the lubricating oil introduced into the gear case to flow out is opened on a front end side of the gear case.