Dual propeller assemblies for driving engagement by a propeller drive shaft may include at least two propellers having a forward propeller and a rear propeller rearwardly of the forward propeller. The forward propeller may include a forward propeller hub with a forward propeller hub wall having a forward propeller hub outer diameter. A forward propeller hub bore may be formed by the forward propeller hub wall and configured to receive the propeller drive shaft for driving engagement of the forward propeller hub thereby. The forward propeller hub bore may form a passageway for flow of exhaust gas configured to traverse the forward propeller between the propeller drive shaft and the forward propeller hub wall. The rear propeller may include a rear propeller hub with a rear propeller hub wall having a rear propeller hub outer diameter less than the forward propeller hub outer diameter of the forward propeller hub wall of the forward propeller hub. A rear propeller hub bore may be formed by the rear propeller hub wall. The rear propeller hub bore may be configured to receive the propeller drive shaft for driving engagement of the rear propeller hub thereby. The passageway for flow of exhaust gas may be configured to traverse the rear propeller hub wall exterior to the rear propeller hub bore of the rear propeller hub.

A mobile emissions control system is provided for diesel engines operated on ocean-going ships at-berth. The emissions control system comprises two essential elements: an emissions capturing system and an emissions control system. The emissions control system may be mounted on a towable chassis or mounted on a barge, allowing it to be placed alongside ocean-going ships at-berth. The emission capturing system captures exhaust from a ship's diesel engine and conducts it into the emissions control system, which cleans the exhaust and then passes clean air into the atmosphere through an exhaust outlet.

An outboard motor includes a mount on which an engine is mounted, an engine cover, and a sealing structure. The engine cover is divisible into a top portion, a front bottom portion, and a side bottom portion. A first seal in the sealing structure integrally includes a first portion, a second portion, and a third portion. The first portion seals the boundary between the top portion, the front bottom portion, and the side bottom portion. The second portion seals the boundary between the front bottom portion, the mount, and the side bottom portion. The third portion seals the boundary between the front bottom portion and the side bottom portion.

The present disclosure is directed toward a marine exhaust system in which the marine exhaust is directed into the water via an exhaust system integrated within a marine rudder. Exhaust travels from the engine to the rudder via a pipe or tube and is expelled through a cavity in the rudder outward into the water. A swivel is located in the system to allow the rudder to rotate in normal steering operations to allow at least a portion of the exhaust pipe or tube to remain static.

An outboard propulsion system comprising a first portion for attachment to a boat, wherein the first portion is fixed about a substantially vertical axis, and a second portion connected to the first portion and configured to rotate about a steering axis, wherein the first portion comprises a sealed housing enclosing a member having a longitudinal axis relative to which it may move and the second portion comprises a gear configured to engage with the member such that movement of the member relative to its longitudinal axis generates rotational movement of the gear about the steering axis, and wherein the sealed housing comprises a sensor configured to determine the position of the member within the sealed housing.

An outboard motor includes an engine main body, and an intake device to supply air to the engine main body. The intake device includes a main intake pipe including a first intake pipe and a second intake pipe connected to a downstream end of the first intake pipe and extending at an angle with respect to an axial direction of the first intake pipe and through which the air supplied to the engine main body flows, and an extension pipe extending from a connection between the first intake pipe and the second intake pipe and including a resonance chamber therein. The extension pipe includes an extended peripheral wall and an end wall that closes the resonance chamber except for a portion adjacent to the main intake pipe.

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 V-type engine in which exhaust pipe arrangement is easily performed even in a V-type engine and that can be downsized even when a catalyst is installed. The engine has cylinders where pistons operate are arranged in a V-shape, a crankshaft driven by the driving of the pistons is disposed vertically, exhaust pipes communicating with exhaust openings in the respective banks of a cylinder head are included, merging exhaust pipes (exhaust pipes) in the respective banks are drawn toward a side of the cylinder head to be merged, and a catalyst holder that holds a catalyst is provided in a merge portion of the merging exhaust pipes. In this manner, since the merging exhaust pipes in the respective banks are merged and the catalyst holder is provided in this merge portion, exhaust gas from each bank can be purified by the catalyst.

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, a gearcase connected to the engine unit housing, and an exhaust system, the exhaust system including an idle relief passage fluidly communicating with an exhaust passage, the idle relief passage having an idle relief outlet, the idle relief passage extending through the engine unit housing for supplying exhaust gases from the at least one combustion chamber to an exterior of the engine unit housing via the idle relief outlet, the idle relief outlet being disposed vertically higher than the exhaust outlet and vertically lower than a waterline when the outboard engine assembly is mounted to a watercraft and the watercraft is at rest, and a propulsion device operatively connected to the engine.

A mobile emissions control system is provided for diesel engines operated on ocean-going ships at-berth. The emissions control system comprises two essential elements: an emissions capturing system and an emissions control system. The emissions control system may be mounted on a towable chassis or mounted on a barge, allowing it to be placed alongside ocean-going ships at-berth. The emission capturing system captures exhaust from a ship's diesel engine and conducts it into the emissions control system, which cleans the exhaust and then passes clean air into the atmosphere through an exhaust outlet.