Abstract: A marine drive is for propelling a marine vessel in a body of water. The marine drive has a supporting frame configured to support the marine drive with respect to the marine vessel, an extension leg depending on the supporting frame, a motor housing depending on the extension leg, the motor housing for containing an electric motor, and a vibration isolating joint which couples the extension leg to the supporting frame. The vibration isolating joint having an isolating connector assembly including an elastomeric member which is clamped between the extension leg and the supporting frame and configured to limit transfer of vibrations from the extension leg to the supporting frame, and a compression limiter which prevents over clamping of the elastomeric member during assembly of the extension leg and the motor housing.

Abstract: A marine drive has a primary exhaust outlet on its lower gearcase that discharges a primary flow of exhaust gas from the engine to seawater in which the marine drive is situated. A secondary exhaust outlet is located on the marine drive above the primary exhaust outlet and discharges a secondary flow of exhaust gas from the engine to atmosphere around the marine drive at least when the engine is operated at an idle speed. A tertiary exhaust outlet is located on the marine drive between the primary and secondary exhaust outlets, and discharges a tertiary flow of exhaust gas from the engine to the seawater or to the atmosphere depending upon a current location of the tertiary exhaust outlet with respect to the seawater. A muffler is configured to reduce noise emanating from the tertiary exhaust outlet.

Abstract: A stern drive for a marine vessel, the stern drive having a drive assembly configured to generate a thrust force in water, a powerhead configured to power the drive assembly, and a mounting assembly configured to couple the drive assembly to the transom outside of the marine vessel and to suspend the powerhead on the transom inside of the marine vessel. The mounting assembly has a vibration dampening member which isolates vibrations of the drive assembly and the powerhead relative to the transom. The powerhead, and the mounting assembly are installed on the marine vessel as a single component from outside the transom.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A system for controlling exhaust flow from an internal combustion engine powering a marine propulsion device includes a primary exhaust conduit having an upstream end receiving exhaust gas from the internal combustion engine and a downstream end discharging exhaust gas to a body of water via a gearcase housing. A bypass exhaust conduit has an upstream end receiving exhaust gas from the primary exhaust conduit and a downstream end discharging exhaust gas from a bypass outlet of the marine propulsion device. A bypass valve is selectively openable to allow exhaust gas to flow through the bypass conduit. A control module is in signal communication with the bypass valve. The control module opens the bypass valve to divert the exhaust gas through the bypass conduit and out the bypass outlet in response to selection of a control mode of the marine propulsion device other than a default lever control mode.

Abstract: A marine drive has a primary exhaust outlet on its lower gearcase that discharges a primary flow of exhaust gas from the engine to seawater in which the marine drive is situated. A secondary exhaust outlet is located on the marine drive above the primary exhaust outlet and discharges a secondary flow of exhaust gas from the engine to atmosphere around the marine drive at least when the engine is operated at an idle speed. A tertiary exhaust outlet is located on the marine drive between the primary and secondary exhaust outlets, and discharges a tertiary flow of exhaust gas from the engine to the seawater or to the atmosphere depending upon a current location of the tertiary exhaust outlet with respect to the seawater. A muffler is configured to reduce noise emanating from the tertiary exhaust outlet.

Abstract: A marine propulsion device includes an internal combustion engine powering the marine propulsion device and an engine compartment containing the engine. A primary exhaust passageway routes exhaust gas away from the engine and out of the engine compartment. A sound enhancement assembly communicates with the primary exhaust passageway. The sound enhancement assembly includes a sound enhancement device tuned to amplify exhaust sounds of a predetermined frequency and a sound duct downstream of the sound enhancement device that transmits the amplified exhaust sounds to an area outside the engine compartment. The sound enhancement device isolates the sound duct from the exhaust gas. A method for modifying sounds produced by an exhaust system of the internal combustion engine is also disclosed.

Abstract: A marine drive includes an engine; an exhaust conduit that conveys exhaust gases from the engine to an idle relief outlet on the marine drive, wherein the idle relief outlet discharges the exhaust gases to atmosphere when the marine drive is operated at an idle speed; and an idle relief muffler having a muffler inlet that receives the exhaust gases from the exhaust conduit, a muffler outlet that discharges the exhaust gases to the idle relief exhaust outlet, and a drain for draining water from the idle relief muffler. The muffler inlet conveys exhaust gases into the idle relief muffler in a direction that is oriented away from the muffler outlet and away from the drain, such that water in the exhaust gases is encouraged to separate from the exhaust gases and then drain from the idle relief muffler via the drain.

Abstract: 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.

Abstract: 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.

Abstract: An outboard motor includes an internal combustion engine and a cowl covering the engine. An air vent allows intake air into the cowl, an air intake duct routes the intake air from the air vent to the engine, and a throttle body meters flow of the intake air from the air intake duct into the engine. A sound enhancement device is located proximate the throttle body. A sound duct is provided, and has an inlet end located proximate the sound enhancement device and an outlet end located proximate an outer surface of the cowl. The sound enhancement device is tuned to amplify a first subset of sounds having a desired frequency that are emitted from the throttle body, and the sound duct transmits the amplified sounds to an area outside the cowl. A method for modifying sounds produced by an air intake system of an outboard motor is also provided.

Abstract: An outboard motor can be coupled to a transom of a marine vessel via the described rigging system. The rigging system includes a plurality of engine-sourced lines extending from an engine of the outboard motor, through an aperture in the motor housing, and to the marine vessel. A protective tube surrounds the plurality of engine-sourced lines and has a first end coupled to the motor housing and a second end coupled to the marine vessel. A rigging center is located aboard the marine vessel and holds distal ends of each of the engine-sourced lines. A plurality of connectors is provided on the distal ends of the engine-sourced lines. At the rigging center, each engine-sourced line is configured to be coupled, via a respective connector, to a corresponding vessel-sourced line. The vessel-sourced lines are in turn connected to respective engine-related devices aboard the marine vessel.

Abstract: A system for mounting an outboard motor propulsion unit to a marine vessel transom includes a support cradle having a head section coupled to a transom bracket and a pair of arms extending aftward from the head section and along opposite port and starboard sides of the propulsion unit. A pair of upper mounts is provided, each upper mount in the pair coupling a respective arm to the propulsion unit aft of a center of gravity of an engine system of the propulsion unit. A pair of lower mounts is also provided, each lower mount in the pair coupling the propulsion unit to the transom bracket. The pair of upper mounts is located aft of the pair of lower mounts when the propulsion unit is in a neutral position, in which the propulsion unit is generally vertically upright and not tilted or trimmed with respect to the transom.

Abstract: Exhaust systems are for outboard marine engines that are configured to propel a marine vessel in a body of water. An intermediate exhaust conduit is configured to receive the exhaust gas from the primary exhaust conduit. A primary muffler receives the exhaust gas from a intermediate exhaust conduit. A secondary muffler receives the exhaust gas from the primary muffler. An idle relief outlet discharges the exhaust gas from the secondary muffler to atmosphere. A bypass valve is positionable into an open position wherein the exhaust gas is permitted to bypass the secondary muffler and flow from the primary muffler to the idle relief outlet and into a closed position wherein the exhaust gas is not permitted to bypass the secondary muffler and instead flows from the primary muffler to the idle relief outlet via the secondary muffler.

Abstract: An outboard motor includes an internal combustion engine powering the outboard motor and a cowl covering the engine and having a vent allowing air under the cowl. A throttle body meters flow of the air into the engine and an intake structure downstream of the throttle body delivers the metered airflow to one or more combustion chambers in a cylinder block of the engine. A sound enhancement assembly in acoustic communication with the intake structure collects sounds emitted by the engine. The sound enhancement assembly is configured to amplify a subset of the collected sounds that have frequencies within a desired frequency range. A method for modifying sounds produced by an air intake system of an internal combustion engine powering an outboard motor is also disclosed. The method includes positioning a sound enhancement assembly in acoustic communication with an air intake passageway located downstream of the engine's throttle body.

Abstract: An air intake system for a marine engine has a throttle body and a throttle plate that is rotatably supported within the throttle body. The throttle plate is rotatable to regulate air flow through the throttle body from a first region on a first side of the throttle plate to a second region on a second side of the throttle plate. An air conduit has an air conduit inlet and an air conduit outlet. A noise cancelling device comprises a pass-though chamber. The pass-through chamber has a chamber inlet that receives the air flow from the air conduit, a chamber outlet that discharges the air flow to the idle air control valve, and a pass-through interior between the chamber inlet and chamber outlet. The pass-though chamber is configured to cancel noise emanating from the idle air control valve.

Abstract: Systems and methods are for controlling internal combustion engines having a plurality of piston-cylinders that cause rotation of a crankshaft. A crankshaft sensor is configured to sense rotational speed of the crankshaft. A controller is configured to calculate an acceleration for each piston-cylinder based upon the rotational speed of the crankshaft and then balance the accelerations of the respective piston-cylinders by modifying a combustion input to one or more of the piston-cylinders in order to reduce engine vibration.

Abstract: Idle relief mufflers are configured to discharge exhaust gases from an outboard motor to atmosphere surrounding the outboard motor when an internal combustion engine of the outboard motor is operated at idle and at low speeds. The idle relief mufflers comprise a housing having an open interior, an inlet port configured to convey the exhaust gases to the open interior, and an outlet port configured to discharge the exhaust gases from the open interior. An exhaust grommet is connected to the outlet port. The exhaust grommet comprises a body that is configured to engage with a cowl of the outboard motor and an extension that extends through the outlet port and protrudes into the open interior. The extension and the body together define a through-bore that is configured to convey the exhaust gases from the open interior to the atmosphere.