Abstract: An exhaust manifold includes first to eighth upstream exhaust pipes extending respectively from first to eighth cylinders ignited in that order; first to fourth midway exhaust pipes extending respectively from a joint of extended ends of the first and fifth upstream exhaust pipes, a joint of extended ends of the second and sixth upstream exhaust pipes, a joint of extended ends of the third and seventh upstream exhaust pipes, and a joint of extended ends of the fourth and eighth upstream exhaust pipes; and first and second downstream exhaust pipes extending respectively from a joint of extended ends of the first and third midway exhaust pipes and a joint of extended ends of the second and fourth midway exhaust pipes for communicating the respective joints to the ambient atmosphere.

Abstract: A watercraft propulsion system has a control lever for giving instructions regarding operating mode and output power from a source of driving force. A controller sets a propeller driving mode according to instructions given from the control lever. In an embodiment, an electric motor and an engine are included in the propulsion system, and the controller simultaneously controls both the engine and motor based on inputs from the control lever and sensed conditions.

Abstract: A remote control device can be provided in a watercraft equipped with at least three outboard motors for operating the outboard motors by remote control. The remote control device can have a pair of shift levers and can be provided with a detection device for detecting positions of the shift levers. A remote control-side ECU can control the outboard motors 11 by signals from the detection device. The remote control-side ECU can include a plurality of ECUs corresponding to the outboard motors. The detection device can include a plurality of detection devices for the outboard motors disposed on the sides of the stern of a hull and one for the outboard motor disposed between the side outboard motors. Each of the detection devices can be connected to a respective one of the remote control-side ECUs.

Abstract: A steering method for a boat with a marine propulsion unit at the stern is provided in which a reaction torque is applied to a steering wheel in response to external force to the boat. The steering method includes: detecting a steering angle and the behavior of the boat; determining whether or not the turning of the steering wheel is in an initial phase based on the detected steering angle and the behavior of the boat; and applying the reaction torque to the steering wheel in response to the determination.

Abstract: An air passage and a cooling water passage can be formed in an intercooler provided on a small planing boat. A cooling water inlet of a cooling water passage in the intercooler can be provided at the lower end of the intercooler. A cooling water outlet can be at the upper end of the intercooler. The intercooler can be vertically elongated and disposed at the front side of the engine. Further, a discharge port of a supercharger can be directed upwardly and an air inlet of the intercooler can be provided on the intercooler at the upper part. Furthermore, the intercooler, the supercharger and an intake manifold can be arranged such that when viewed in the lateral direction, the intercooler and supercharger overlap each other and when viewed in the longitudinal direction, the intercooler and intake manifold can also overlap each other. Moreover, the intercooler can be of a two-pass type.

Abstract: A supercharger can have a lubrication system that includes a speed increasing mechanism, accommodated in a second housing, for increasing the rotation speed of a drive shaft and transmitting the increased rotation speed to a rotary shaft. An oil sump can be configured to for hold lubricant oil for lubricating the speed increasing mechanism. A pump mechanism can be driven by the rotation of the drive shaft to supply the lubricant oil held in the oil sump to the speed increasing mechanism, in which the pump mechanism is constituted with a screw pump made up of a screw provided on the drive shaft. A pump chamber can rotatably support the drive shaft and accommodate the screw. An oil introduction hole and an oil introduction tube can connect the oil sump and the interior of the pump chamber, and a gap can be formed between the screw and the pump chamber.

Abstract: An outboard drive includes a prime mover having an output shaft. A driveshaft is coupled with the output shaft. Both shafts having axes that extend at least generally parallel to each other. A propulsion device is coupled with the driveshaft. The prime mover rotates the output shaft to drive the propulsion device through the driveshaft. A speed change mechanism is positioned between the output shaft and the driveshaft. The speed change mechanism changes a rotational speed of the output shaft transmitted to the driveshaft.

Abstract: A control unit for controlling multiple propulsion units can include plural propulsion units mounted at the stern of the boat to generate thrust. A control unit can be used to control the driving of each propulsion unit, and a target speed setting device can be used to establish a target speed of the boat, in which the control unit controls the driving of each propulsion unit according to the preset driving pattern to attain the target speed.

Abstract: An outboard motor has a cowling enclosing the engine. A sidewall of the cowling has an air introduction opening for introducing ambient air to an air introduction chamber within the cowling. A protruded suction opening of an air duct in the air introduction opening has a flange extending generally toward the air introduction opening so as to deflect water from the opening.

Abstract: A cooling water attachment device for a small boat can include a joint attachment part having a cooling water inlet/outlet port provided on a side surface of an engine opposite an exhaust pipe. A joint member can be formed with a recess for communication with the cooling water inlet/outlet port and can be attached to the joint attachment part. Branch piping and connection piping can be connected to the joint member. The branch piping and the connection piping can extend parallel to the side surface of the engine. The joint member can be attached below the lowest end of a water cooling jacket part, and the branch piping can extend downward from the joint member.

Abstract: A shift cutout control system is provided that can comprise a shift mechanism, an engine electronic control unit, a remote controller, and an ignition control means. The shift mechanism can switch a rotation of a propeller shaft into one of a neutral, forward, and reverse drive state. The propeller shaft can be driven by an output power of an engine. The engine electronic control unit can control a drive state of the engine. The remote controller can transmit a control signal to the engine electronic control unit to achieve a target drive state. The ignition control means can initiate an ignition cutout in the engine when an operating position signal from a lever position detector indicates that a control lever is in a neutral position and a shift position signal from a shift position detector indicates that a shift position is not in neutral.

Abstract: A casing of an outboard motor can be formed with an upper casing, a lower casing, and an extension casing interposed between the upper casing and the lower casing. Water guiding passages, which can be formed with jacket sections or the like, can extend along both inner side surfaces of the extension casing. The water guiding passages can communicate with a space. Water that leaks from a cooling water pump in the space is allowed to flow through the water guiding passages so as to be used as cooling water. A cooling water inlet of each jacket section can be made at a bottom end of a partition, while the cooling water outlet of each jacket section can be made at a top end of a partition. A bottom of each jacket section can be formed with a bottom closure member.

Abstract: A remote control unit can be used for a boat having a plurality of propulsion units to perform output adjustment and tilt/trim angle adjustment of the propulsion units. Operating levers can be capable of forward and backward rotational movement to effect shift operation and throttle operation of the propulsion units and can be respectively provided upright on a left side surface and right side surface of a body. A plurality of tilt/trim angle adjustment switches can correspond to respective propulsion units and can be provided at positions where they can be operated with fingertips of a hand resting on a palm portion of a top surface of the body with the fingertips pointing generally forward. The palm portion of the top surface can be free of switches.

Abstract: An outboard motor has a cowl having a top cowl and a bottom cowl that are detachably connected using a clamp apparatus. The clamp apparatus has a clamp engaging member on the top cowl, a clamp fixing member on the bottom cowl, and a clamp for connecting the top and bottom cowls. The clamp has an engaging section for engaging the clamp engaging member, a fixing section fixed on the bottom cowl by the clamp fixing member, a mounting pivot formed on the fixing section, and a supporting pivot linked to the mounting pivot. A line is defined between the engaging section and the mounting pivot. In an open clamp state, the supporting pivot is positioned away from the cowl beyond the line. In a closed clamp state, the supporting pivot is positioned adjacent to the cowl within the line. A biasing spring biases the clamp main body toward the cowl at least in the open clamp state.

Abstract: An engine ECU provided in a boat propulsion system is connected to a remote control ECU provided in a remote control device, the remote control ECU is connected to a gauge ECU provided in an information display device, and control is performed so as to start communication between the remote control ECU and the gauge ECU after a power supply is turned on and after authentication of the engine ECU and the remote control ECU is completed. Accurate information on the boat propulsion system can be transmitted in response to a request from the information display device at a time of initialization at a system start.

Abstract: An engine in an outboard motor includes a first rotation angle sensing device arranged to sense a rotation angle of a crankshaft and second rotation angle sensing device arranged to sense a rotation angle of an exhaust camshaft. A reverse rotation determination section is arranged to determine an occurrence of a reverse rotation of the crankshaft based on of a rotation angle sensed by the first rotation angle sensing device and a rotation angle sensed by the second rotation angle sensing device. A gear mechanism operation section forceaby shifts a shift gear mechanism into a neutral state when a reverse rotation of the crankshaft is sensed by the reverse rotation determination section. Water is surely prevented from entering the internal combustion engine and can minimize an increase in the manufacturing cost and simplify the maintenance work of the internal combustion engine.

Abstract: In engine temperature display device for a watercraft, an engine temperature data value is calculated based on a detection signal of a temperature of an engine of an outboard motor. The engine temperature data value is sent to an engine state display device installed in a watercraft by a LAN. A control portion of the engine state display device computes the engine temperature data value based on a plurality of threshold temperatures of a standard engine model stored in a nonvolatile memory, and converts the data value into a display data for indicating a temperature level among a plurality of temperature levels. The display data is displayed on a display device on the watercraft. An engine temperature data value calculating and sending device computes using a plurality of threshold values on an engine block wall temperature specific to an engine, and sends the appropriately converted engine temperature data value.

Abstract: An electrical component box which can be provided under a maintenance opening in an engine compartment on a water vehicle, can include a box body provided with an electrical unit and a cover member. The box body can be attached to a bulkhead so that a mounting surface for an electrical unit extends generally vertically. Engaging frames can be provided on the upper face of the box body. Also, engaging clamps can be provided on the upper side of the cover member to be engaged with the engaging frames by one-touch operation. A bottom cover can be provided under the box body to cover the bottom side of the electrical unit and the upper side, both lateral sides and the front side of the electrical unit can be covered by the cover member.

Abstract: A boat control system detects a wire break status in a duplicated communication system. A hull of a boat is provided with a main remote control side ECU and a subremote control side ECU, and the subremote control side ECU communicates with an engine side ECU via the main remote control side ECU. Both of the remote control side ECUs are provided with storage buffers in which communication status confirmation data transmitted between nodes is stored. A broken wire detection section of the engine side ECU starts a determination when a system is started, and broken wire detection sections of both of the remote control side ECUs start a determination when communication status confirmation data is received from another node. Data indicating that communication is in an abnormal status is stored as an initial value in a main remote control data storage buffer.

Abstract: A remote control operation unit can have a remote control shift lever through which a boat operator can remotely control a forward drive mode, a neutral mode, and a reverse drive mode. A boat propulsion unit can have a shift switching device for shifting and a shift actuator for operating the shift switching device. A controller can be used to control the operation of the shift actuator in response to the operation amount of the remote control shift lever. The controller can also be configured to control the shift actuator such that in the case where the remote control shift lever has been shifted between a neutral position and a forward position or reverse position, when an engine is stopped and when shifting is not completed within a certain period of time, the shift actuator stops shifting operation.