A marine outboard motor is provided with an internal combustion engine comprising an engine block defining at least one cylinder, an air intake configured to deliver a flow of air to the at least one cylinder, a crankcase in which a crankshaft is mounted for rotation about a crankshaft axis which is substantially vertical when the marine outboard is vertical, and a crankcase ventilation system configured to vent blow-by gases from the crankcase and to supply vented blow-by gases to the air intake. The crankcase ventilation system comprises a lubricant separation chamber for separating lubricant from the blow-by gases. The lubricant separation chamber is defined by the crankcase and extends along the length of the crankcase substantially parallel to the crankshaft axis.

An outboard motor includes an engine to rotate a propeller and an engine cover that houses the engine. The engine cover includes two divided covers disposed above the engine and that directly face the engine. The two divided covers include two connections that are connected together and that overlap the engine in a plan view.

An outboard motor comprises an engine and a cover that covers the periphery of the engine. The cover includes an outer cover that defines an outer appearance and an inner cover that covers the engine inside the outer cover. The outer cover comprises an outer side division structure that can be divided into a plurality of parts, and the inner cover has a structural part providing access to the engine.

An exhaust pipe has an upstream-side exhaust pipe extending downward from an engine to house a catalyst for exhaust gas purification, and a downstream-side exhaust pipe located downstream of the upstream-side exhaust pipe, and extending upward from the catalyst and then bending downward. Under a configuration in which an exhaust pipe is disposed below an engine, with a simple configuration, a catalyst is hardly exposed to water.

A method of operating a marine vessel hybrid propulsion system having a propulsion shaft and a propeller, an internal combustion piston engine in force transmission connection with the propulsion shaft, and an electric motor-generator in force transmission connection with the propulsion shaft and/or with the piston engine. The internal combustion piston engine can be started by applying electric power from an on-board power source to the electric motor-generator and rotating the internal combustion piston engine by the electric motor-generator and rotational speed of the internal combustion piston engine is accelerated to a predetermined limit rotational speed without attempting to start the internal combustion piston engine, and only after the rotational speed of the internal combustion piston engine reaches the predetermined limit rotational speed, the internal combustion piston engine is started.

A method of operating a marine vessel hybrid propulsion system having a propulsion shaft and a propeller, an internal combustion piston engine in force transmission connection with the propulsion shaft, and an electric motor-generator in force transmission connection with the propulsion shaft and/or with the piston engine. The internal combustion piston engine can be started by applying electric power from an on-board power source to the electric motor-generator and rotating the internal combustion piston engine by the electric motor-generator and rotational speed of the internal combustion piston engine is accelerated to a predetermined limit rotational speed without attempting to start the internal combustion piston engine, and only after the rotational speed of the internal combustion piston engine reaches the predetermined limit rotational speed, the internal combustion piston engine is started.

An intake plenum is for a marine engine, the marine engine having first and second throttle devices for controlling flow of intake air to the marine engine. The intake plenum has an airbox providing an expansion volume, first and second inlets that convey the intake air in parallel to the expansion volume, first and second outlets that convey the intake air in parallel from the expansion volume to the first and second throttle devices, and first and second Helmholtz-style attenuator devices located at the first and second outlets, respectively. Together the first and second inlets, expansion volume, and first and second Helmholtz-style attenuator devices are configured to attenuate different frequencies of sound emanating from the marine engine via the first and second outlets.

A marine drive has a powerhead and a cowling enclosing the powerhead. The cowling comprises a first cowl portion and a second cowl portion coupled to the first cowl portion and being movable with respect to the first cowl portion into and between a closed cowl position in which the powerhead is enclosed by the cowling and an open cowl position in which the powerhead is accessible. A recoil starter is for starting the marine drive. The recoil starter extends through the second cowl portion and comprises a pull-start handle coupled to the marine drive via a recoil cable. Manually pulling the pull-start handle out of a recoiled position with respect to the marine drive causes the marine drive to start. The pull-start handle is also movable into an offset position, in which the second cowl portion is freely movable into and out of the open and closed cowl positions.

A marine engine has an intake camshaft, an exhaust camshaft, and a crankshaft. Combustion in the marine engine causes rotation of the crankshaft which in turn causes rotation of the intake camshaft and exhaust camshaft. Rotation of the intake camshaft operates intake valves for controlling inflow of air to the marine engine. Rotation of the exhaust camshaft operates exhaust valves for controlling outflow of exhaust gas from the marine engine. A cam phaser is located at least partially inside at least one of the intake camshaft and the exhaust camshaft and is configured to vary a timing of operation of at least one of the intake valves and exhaust valves.

A marine outboard motor for a marine vessel. The marine outboard motor includes: a housing comprising a chamber and at least one inlet arranged to be submerged, in use, into a body of water in which the marine outboard motor is operated, in order to draw water into the chamber; an engine assembly comprising an internal combustion engine; a drive shaft positioned in the housing, wherein the drive shaft is coupled to the internal combustion engine to drive a propulsion arrangement; a cooling system for cooling the internal combustion engine, the cooling system configured convey drawn water along a coolant flow path through the housing to deliver the drawn water to the internal combustion engine; and a sleeve by which the drive shaft is sealed from drawn water within the housing, the sleeve having first and second ends, wherein at least a part of the drive shaft is encased within the sleeve.