A marine propulsion system configured to propel a marine vessel in a body of water. The marine propulsion system includes an engine and an exhaust system that conveys exhaust gas from the engine. A controller controls the marine propulsion system and includes a memory module that stores operating modes with corresponding sound profiles for controlling the marine propulsion system. An input device is provided for selecting one of the operating modes for controlling the marine propulsion system. Selecting a first operating mode causes the marine propulsion system to sound different than selecting a second operating mode.

A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

A method is for making a marine drive for propelling a marine vessel in water. The method includes providing a gearcase; installing a propeller shaft assembly that extends forwardly from the gearcase; coupling front and rear propellers to the propeller shaft assembly, forwardly of the gearcase, such that rotation of the propeller shaft assembly causes rotation of the front and rear propellers, respectively, which thereby propels the marine vessel in the water; and reducing deleterious effects of cavitation on the gearcase by the combination of forming the gearcase with a wide trailing end portion, in particular to maintain pressure alongside the gearcase, and configuring the front and rear propellers so that the front propeller absorbs more torque/thrust load than the rear propeller during said rotation.

A stern drive arrangement is for propelling a marine vessel in water. A diverter valve is movable into and between an open position in which the exhaust gas is allowed to flow through the above-water outlet via the secondary exhaust conduit and a closed position in which the exhaust gas is at least partially prevented from flowing through an above-water outlet via a secondary exhaust conduit. Via a bypass conduit, the exhaust gas in the secondary exhaust conduit can bypass the diverter valve and discharge to atmosphere when the diverter valve is in the closed position.

A marine drive for propelling a marine vessel includes a lower gearcase, a propeller shaft laterally extending through the lower gearcase and configured to support a propeller, a propeller shaft bearing hub supporting the propeller shaft in the lower gearcase, and an exhaust passage that conveys exhaust gas through the lower gearcase to an underwater discharge outlet. The exhaust passage includes a first leg that conveys the exhaust gas downwardly in the lower gearcase and a second leg that redirects the exhaust gas laterally from the first leg to the underwater discharge outlet. The propeller shaft bearing hub comprises curved vanes that laterally redirects the exhaust gas from the first leg towards the underwater discharge outlet.

A marine drive for propelling a marine vessel includes a lower gearcase, a propeller shaft laterally extending through the lower gearcase and configured to support a propeller, a propeller shaft bearing hub supporting the propeller shaft in the lower gearcase, and an exhaust passage that conveys exhaust gas through the lower gearcase to an underwater discharge outlet. The exhaust passage includes a first leg that conveys the exhaust gas downwardly in the lower gearcase and a second leg that redirects the exhaust gas laterally from the first leg to the underwater discharge outlet. The propeller shaft bearing hub comprises curved vanes that laterally redirects the exhaust gas from the first leg towards the underwater discharge outlet.

A boat drive including combustion engine located within the hull and a drive unit located outside the hull. The drive has a propeller shaft and an exhaust system with an exhaust duct and an outlet. The exhaust duct connects the engine to the exhaust outlet for carrying away exhaust gases from the engine and cooling water introduced into the exhaust duct. The exhaust outlet is arranged in the propeller shaft. A first exhaust release opening is arranged in the exhaust duct, between the engine and the exhaust outlet, so that during operation, a first fraction of the exhaust gases and cooling water is discharged through the first exhaust release opening, while a second fraction of the exhaust gases and the cooling water is discharged through the exhaust outlet. A device is provided for adjusting the first fraction that can be discharged through the first exhaust release opening.

A boat drive including combustion engine located within the hull and a drive unit located outside the hull. The drive has a propeller shaft and an exhaust system with an exhaust duct and an outlet. The exhaust duct connects the engine to the exhaust outlet for carrying away exhaust gases from the engine and cooling water introduced into the exhaust duct. The exhaust outlet is arranged in the propeller shaft. A first exhaust release opening is arranged in the exhaust duct, between the engine and the exhaust outlet, so that during operation, a first fraction of the exhaust gases and cooling water is discharged through the first exhaust release opening, while a second fraction of the exhaust gases and the cooling water is discharged through the exhaust outlet. A device is provided for adjusting the first fraction that can be discharged through the first exhaust release opening.

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 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.