Boat having prioritized controls

An outboard motor control system can have a first PTT switch and a second PTT switch in a first steering station and in a second steering station respectively, and a third PTT switch in a location outside of a boat hull. Operation instruction given by each PTT switch can be input to a first microcomputer of a first ECU. The first microcomputer can determine if the inputted operation instruction is to be sent to the outboard motor, based on which PTT switch the operation instruction came from, whether the main switch is ON or OFF, and which steering station has precedence in boat control.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2006-087325, filed on Mar. 28, 2006, the entire contents of which is hereby expressly incorporated by reference herein.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present inventions relate to boats having boat propulsion units, such as outboard motors, and more specifically to control of boat propulsion units in accordance with control signals transmitted by an onboard device or devices.

2. Description of the Related Art

Outboard motors mounted on the outside of boats are used for providing propulsion and steering functions for boats. In recent years, onboard LAN systems have been developed to replace outboard motors' throttle control mechanism operated via the cables installed onboard. An example of such a system is disclosed in Japanese Patent Document JP-A-2003-146293. The onboard LAN system connects the outboard motor and the hull by means of a LAN (Local Area Network), and controls the outboard motor by control signals transmitted by an onboard device. The onboard LAN system allows connection of many devices to one cable, simplifying the wiring between the hull and the outboard motor. A PTT (Power Trim and Tilt) switch is also connected to the onboard LAN to control the trim and tilt angles of the outboard motor.

SUMMARY OF THE INVENTIONS

An aspect of at least one of the embodiments disclosed herein includes the realization that in boats having plural PTT switches (for instance, when a PTT switch is provided at each steering/control station in a boat having plural steering/control stations, or when a separate PTT switch is provided in a location outside of the hull), the trim and tilt angle operation commands input by each PTT switch can be processed to prevent outboard motor operation that was not intended by a boat operator or by a helmsman, or to prevent malfunction of the outboard motor.

Thus, in accordance with at least one of the embodiments disclosed herein, a boat can comprise an outboard motor operating means having a first steering station and a second steering station and connected to a boat propulsion unit, a plurality of operation instruction output means for transmitting to the outboard motor operating means operation instructions for controlling the trim and tilt angles of the boat propulsion unit, and an operation instruction selecting means for selecting the operation instructions transmitted by the plurality of operation instruction output means and for sending the selected operation instruction to the boat propulsion unit. The plurality of operation instruction output means can include a first operation instruction output means mounted at the first steering station, a second operation instruction output means mounted at the second steering station, and a third operation instruction output means mounted on the outer surface of the boat propulsion unit or on a hull of the boat. The operation instruction selecting means can prioritize the first operation instruction output means, the second operation instruction output means, and the third operation instruction output means, to process the operation instructions in accordance with the priority given to each means.

In accordance with at least one of the embodiments disclosed herein, a boat comprises a propulsion unit, a first control station, a second control station, a control unit, a first switch mounted at the first control station, and a second switch mounted at the second control station. The first and second switches are configured to transmit operation instructions to control the trim and tilt angles of the propulsion unit. The control unit is configured to process the operation instructions transmitted by the first and second switches based on a priority given to each switch and to send operation instructions to the propulsion unit to control the trim and tilt angles of the propulsion unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a perspective view of a boat10according to an embodiment. The embodiments disclosed herein are described in the context of a boat having an outboard motor because these embodiments have particular utility in this context. However, the embodiments and inventions herein can also be applied to other marine vessels having other types of propulsion systems, including personal watercraft and small jet boats, as well as other land and marine vehicles. It is to be understood that the embodiments disclosed herein are exemplary but non-limiting embodiments, and thus, the inventions disclosed herein are not limited to the disclosed exemplary embodiments.

As shown inFIG. 1, the boat10can include a hull12and a propulsion unit, such as an outboard motor13. Two control stations, also referred to as steering stations15, can be provided on the hull12. A first steering station15A can be assigned as a main steering station, and a second steering station15B can be assigned as a sub station. In the illustrated embodiment, each of the steering stations15A,15B is equipped with a steering wheel41A,41B, and a shift lever42A,42B. In other embodiments, more or less control equipment can be provided at one or more control stations. The boat10can be controlled either at the first steering station15A or at the second steering station15B.

A rotary switch43, which can be rotated by an ignition key (not shown) inserted therein, can be located at the first steering station15A. The rotary switch43can function as a main switch43aconfigured to select an ON or OFF status of the engine by inserting or removing the ignition key (not shown), as well as a starting switch43band a stop switch43cset up at two different rotational positions. A push button type starting switch43dand a stop switch43ecan be provided at the second steering station15B. The switches described herein can be push button, toggle, rotary or other types of switches known to those of skill in the art.

Push button-type steering station selector switches44A,44B can be provided at the first steering station15A and at the second steering station15B, respectively. Control of the boat can be given selectively to the first steering station15A or to the second steering station15B by actuating the steering station selector switch44A,44B.

In addition, a first PTT (power trim and tilt) switch (a first operation instruction output means)46can be provided in the vicinity of the shift lever42A at the first steering station15A, a second PTT switch (a second operation instruction output means)47can be provided in the vicinity of the shift lever42B at the second steering station15B, and a third PTT switch (a third operation instruction output means)48can be provided on an external surface of the outboard motor13or on the hull of the boat, respectively. Each of these first, second, and third PTT switches46,47,48can be used to input operation instructions for moving the outboard motor13up (UP instruction) and for moving it down (DOWN instruction) in order to adjust tilt and trim. Thus, each of the switches46,47,48can have an UP switch46a,47a,48a, respectively, to input an UP instruction, and a DOWN switch46b,47b,48b, respectively, to input a DOWN instruction. The UP switches46a,47a,48a, and DOWN switches46b,47b,48bcan be push buttons. Operation instruction output can continue while the switch is actuated, and the output can cease once the switch is released.

FIG. 2is a block diagram of an outboard motor control system11according to one embodiment. As shown inFIG. 2, the outboard motor control system11can be an inboard network system provided in the boat10for the purpose of DBW (Drive-By-Wire) operation. The outboard motor control system11can comprise a first remote control box21serving as a main remote control device, a second remote control box22serving as a sub remote control device, a first key-switch assembly23, and a second key-switch assembly24, all provided on the boat12, as well as outboard motor equipment (an outboard motor operating means)25mounted on the outboard motor13, which can be connected by CAN (Controller Area Network) to allow communication with each other. In the aforementioned CAN, connection between the first remote control box21and the second remote control box22, as well as the connection between the first remote control box21and the outboard motor equipment25can be constructed as double connections. While the network is operating normally, one of the connections can serve as a main connection primarily handling data communication, while the other can serve as a sub connection primarily handling communication of control signals. It should be noted that the CAN can be constructed either by wire communication or by wireless communication using infra-red radiation, radio waves, supersonic wave, or other means known to those of skill in the art.

The first remote control box21can have a first ECU (Engine Control Unit)26and a first PTT switch46.

The first ECU26can be connected to the first PTT switch46and various sensors, which are not shown in the diagram. In addition, the first ECU26can have a first microcomputer (steering station selector means, operation instruction selecting means)27, which can control operation of the boat10based on the input signals from the switches and sensors connected to it. The first ECU26also can monitor the signals and data processing of the entire outboard motor control system11by the connections, to the second remote control box22and the outboard motor equipment25.

The second remote control box22can have a second ECU28and a second PTT switch47. The second ECU28can be connected to the second PTT switch47and various sensors, which are not shown in the diagram. In addition, the second ECU28can have a second microcomputer (steering station selector means, operation instruction selecting means)29which can control the boat10in cooperation with the first microcomputer27and under the monitoring and control of the first microcomputer27.

The first key switch assembly23can include plural devices including the main switch43a, the starting switch43b, the stop switch43c, and the steering station selector switch44A configured to input instructions to the first microcomputer27and to implement the instructions in accordance with control by the first microcomputer27.

The second key switch assembly24can have plural devices including the starting switch43d, the stop switch43e, and the steering station selector switch44B configured to input instructions to the second microcomputer29and to implement the instructions in accordance with control by the second microcomputer29.

The outboard motor equipment25can include an engine (not shown) and devices for driving the engine (not shown) as commanded by the boat operator. For example, the outboard motor equipment25can include various sensors. The outboard motor equipment25also can include an engine ECU30, a PTT relay31, a PTT motor32, and a third PTT switch48.

The engine ECU30can handle the control of the outboard motor13. The engine ECU30can be provided with an outboard-motor-mounted microcomputer33configured to control the operation of the engine (not shown) and various associated devices in accordance with the operation instructions received. The outboard-motor-mounted microcomputer33also can output a signal to control the operation of the PTT relay31and the PTT motor32. The PTT motor32can adjust a trim angle and a tilt angle of the outboard motor13by exerting a rotational force to the mounting axis (not shown) where the outboard motor13is mounted to the hull12and making the outboard motor13rotate relative to the hull12. Electric power generated by the engine (not shown) during operation can be supplied to a main battery34aand a sub buttery34b. The third PTT switch48, connected to the outboard-motor-mounted microcomputer33, can input the operation instruction for trim angles and the tilt angles to the outboard-motor-mounted microcomputer33.

As shown inFIG. 3, the first ECU26of the first remote control box21can include, in addition to the configuration shown inFIG. 2, CAN transceivers37a,3b,37cto process communications between the first microcomputer27and the second microcomputer29, and between the first microcomputer27and the outboard-motor-mounted microcomputer33. The first ECU26further can include interfaces38a,38b,38cto perform processing associated with communication with the peripheral devices connected to the first ECU26. The main battery34a, the sub battery34b, a self-hold circuit35, and 5V power supplies36a,36bcan be among the peripheral devices connected to the first ECU26in addition to the configuration shown inFIG. 2.

The first microcomputer27of the first remote control box21can include a DBW microcomputer27aand a communication microcomputer27b. The DBW microcomputer27acan be a main microcomputer and mainly handle data communication. The communication microcomputer27bcan be a sub microcomputer and mainly handle control signal communication.

The DBW microcomputer27acan have a CPU (Central Processing Unit)27cand an operation instruction output-information memory27d. The CPU27ccan implement instructions and process data. The operation instruction output-information memory27dcan store information that can be used to select the operation instruction output to control the trim and tilt angles of the outboard motor13, based on the relevant input from the first, second and third PTT switches46,47,48. The operation instruction output-information memory27dcan be configured in a nonvolatile storage device such as a hard disk or other auxiliary storage that can retain the information stored in the memory after the power supply to the outboard motor control system11is turned off, for example when the main switch43ais turned off. The information stored in the operation instruction output-information memory27dwill be described further below.

The main battery34acan be the primary power source of the first microcomputer27, while the sub battery34bcan be a backup power source. Each battery can supply electric power to the first microcomputer27. Also, the main battery34aand the sub battery34bcan supply electric power to nodes other than the first microcomputer27of the outboard motor control system11, such as the second microcomputer29and the outboard-motor-mounted microcomputer33.

The self-hold circuit35can be interposed between the batteries34a,34band the first microcomputer27to maintain electrical continuity for a prescribed period of time, for example, a prescribed period of time after the release of the first, second or third PTT switch46,47,48that has been actuated.

The DBW microcomputer27acan be connected to an ECU wakeup device (not shown). The ECU wakeup device (not shown) can supply power to the engine ECU30to activate it when either the main switch43aor the first PTT switch46is turned on.

The 5V power supply36acan be connected to the self-hold circuit35and the DBW microcomputer27a, while the 5V power supply36bcan be connected to the self-hold circuit35and the communication microcomputer27b, to supply electric power for driving the DBW microcomputer27aand the communication microcomputer27brespectively while the self-hold circuit35maintains electrical continuity.

The first microcomputer27can output signals to control the trim and tilt angles of the outboard motor13based on the operation instruction input from the first, second, or third PTT switch46,47,48. Operation instructions from the second PTT switch47and the third PTT switch48, can be transmitted to the first microcomputer27by the second microcomputer29and outboard-motor-mounted microcomputer33, respectively. Then, the first microcomputer27can transmit the operation instructions to the outboard-motor-mounted microcomputer33, upon which the trim and tilt angles can be controlled.

In this process, the first microcomputer27can determine if the operation instruction in question is to be transmitted, or which operation instruction is to be transmitted to the outboard-motor-mounted microcomputer33, based on which PTT switch or switches input the operation instructions, whether the main switch43ais ON or OFF, and which of the first steering station15A and the second steering station15B has precedence in boat control. Before making a determination, the first microcomputer27can refer to the information stored in the operation instruction output-information memory27dand evaluate the stored information and the factors described above.

FIGS. 4 through 6are tables showing relationships between the operation instruction input received by the first microcomputer27and the operation instruction output from the first microcomputer27, which can be stored in the operation instruction output-information memory27dof the outboard motor control system11according to an embodiment. As shown in these tables, the relationships can be stored in tables depending on whether the main switch43ais ON or OFF, and on the status of the starting switch43band the stop switch43con the first remote control box21, and the starting switch43dand the stop switch43eon the second remote control box22, in other words, which steering station has precedence in boat control, the first steering station15A or the second steering station15B.

Referring toFIGS. 4-6, methods of the processing of the operation instructions input by the first, second, or third PTT switch46,4748are described below.

Information relating to a relationship between the operation instruction input and the operation instruction output when the main switch43ais OFF can be stored as a first table27d1as shown inFIG. 4.

The self-hold circuit35, upon receiving the operation instruction from the first PTT switch46(first operation instruction), the second PTT switch47(second operation instruction) or the third PTT switch48(third operation instruction), can establish electrical continuity to activate the 5V power supplies36a,36b, thereby supplying electrical power to the DBW microcomputer27a, and to the communication microcomputer27bwhich would otherwise not be supplied with electrical power. Thus, the first microcomputer27, the second microcomputer29and the outboard-motor-mounted microcomputer33can be activated to carry out PTT operation. After a predetermined time period (for example, a short period of time such as several seconds) from the release of the first PTT switch46, the second PTT switch47, or the third PTT switch48that has been actuated, the electrical continuity of the self-hold circuit35can cease and the electrical power from the 5V power supplies36aand36bcan be shut off. Thus, the first microcomputer27, the second microcomputer29and the outboard-motor-mounted microcomputer33stop their operation. Thus, PTT operation can be enabled while the main switch43ais OFF by using the 5V power supplies36a,36b.

When the main switch43ais OFF, equal priority can be given to the operation instructions from the first PTT switch46and those from the third PTT switch48, while lower priority can be given to the operation instructions from the second PTT switch47relative to those from the first and the third PTT switches46,48.

The DBW microcomputer27aof the first microcomputer27can verify that the main switch43ais OFF and can identify whether operation instruction came from the first, second, or third PTT switch46,47,48. Then, the DBW microcomputer27acan refer to the information stored in the first table27d1, and can determine which operation instruction is to be transmitted to the outboard-motor-mounted microcomputer33, or that all of the operation instructions are to be cut off.

Referring to row1-1ofFIG. 4, when the operation instruction is input by the first PTT switch46only, the first microcomputer27can transmit the operation instruction to the outboard-motor-mounted microcomputer33regardless of whether the instruction is an UP instruction or a DOWN instruction (as can also be the case in the processing described below), followed by implementation of trim and tilt angle control of the outboard motor13according to the transmitted operation instruction. This can enable trim and tilt angle control by the first PTT switch46at the first steering station even when the main switch is OFF. Thus, during maintenance, for example, the trim and tilt angles can be controlled from the first steering station, even when the main switch is OFF. This can enable the trim and tilt angle control using the PTT switch at the first steering station even when the main switch is OFF, under the condition that priority is given to the operation instruction from the first steering station, such as when the first steering station is assigned as the main steering station. Thus, controllability of the trim and tilt angles can be improved by the priority given to the first steering station.

When the operation instruction is input by the second PTT switch47only, the first microcomputer27can cut off the operation instruction transmitted by the second microcomputer29without sending it to the outboard-motor-mounted microcomputer33. Consequently, implementation of trim and tilt angle control of the outboard motor13can be prevented (Refer to (1-2)). Thus, adverse effects on trim and tilt angle control of the outboard motor13can be avoided by the priority given to the second steering station15B, such as when the second steering station15B is assigned as the sub steering station.

When the operation instruction is input by the third PTT switch48only, the first microcomputer27can transmit the operation instruction to the outboard-motor-mounted microcomputer33, followed by implementation of trim and tilt angle control of the outboard motor13according to the transmitted operation instruction (Refer to (1-3)). This can enable trim and tilt angle control using the third PTT switch48, located on the external surface of the outboard motor13or exterior of the hull, even when the main switch is OFF. Thus, during maintenance, for example, the trim and tilt angles can be controlled from the outside of the boat propulsion unit or from the hull as may be necessary, even when the main switch is OFF. This can improve the controllability of trim and tilt angles from the outside of the boat propulsion unit or from the hull.

When the operation instructions are input simultaneously by the first PTT switch46and the second PTT switch47, the first microcomputer27can cut off the operation instruction from the second PTT switch47, and transmit the operation instruction from the first PTT switch46to the outboard-motor-mounted microcomputer33(Refer to (1-4)). Thus, the operation instruction from the first PTT switch46can have a higher priority than the operation instruction from the second PTT switch47, and can allow trim and tilt angle control of the outboard motor13based on the aforementioned priority. The first steering station15A can be assigned as the main steering station, and the second steering station15B can be assigned as the sub steering station. The first steering station15A (main steering station) can have precedence in boat control over the second steering station15B (sub steering station), and such prioritized configuration of both steering stations15A,15B can be utilized to prevent trim and tilt angle control that was not intended by a boat operator or a helmsman.

With continued reference toFIG. 4, when the operation instruction is input simultaneously by the first PTT switch46and by the third PTT switch48, the first microcomputer27can cut off both the operation instructions transmitted from the first and the third PTT switches46,48, without transmitting any operation instruction to the outboard-motor-mounted microcomputer33(Refer to (1-5)). This can prevent unintended operation of the outboard motor13when conflicting operation instructions are input simultaneously from the first steering station15A and from the outboard motor13while the operation instruction input from the outboard motor13is enabled, during maintenance, for example.

When the operation instructions are input simultaneously by the third PTT switch48and the second PTT switch47, the first microcomputer27can cut off the operation instruction from the second PTT switch47, and transmit only the operation instruction from the third PTT switch48to the outboard-motor-mounted microcomputer33(Refer to (1-4) and (1-6)). Thus, adverse effects on trim and tilt angle control of the outboard motor13can be avoided by the priority given to the second steering station15B, such as when the second steering station15B is assigned as the sub steering station, and trim and tilt angle control of the outboard motor13from the outside of the outboard motor13can be improved.

In one preferred embodiment, information relating to a relationship between the operation instruction input and the operation instruction output when the main switch43ais ON and the operating station selector switch44A on the first key switch assembly23is ON can be stored in a second table27d2as shown inFIG. 5.

Just as when the main switch43ais OFF, equal priority can be given to the operation instructions from the first PTT switch46and those from the third PTT switch48, while lower priority can be given to the operation instructions from the second PTT switch47relative to those from the first and the third PTT switches46,48.

When the operation instruction is input by the first, second, or third PTT switch46,47, or48, the DBW microcomputer27aof the first microcomputer27can identify the PTT switch from which the operation instruction came, and check which steering station, e.g., the first steering station15A or the second steering station15B, has precedence in boat control. Then, the DBW microcomputer27acan refer to the information stored in the second table27d2and determine which operation instruction is to be transmitted to the outboard-motor-mounted microcomputer33, or that all of the operation instructions are to be cut off.

When the operation instruction is input by the first PTT switch46only, or by the third PT switch48only, the first microcomputer27can transmit the relevant operation instruction to the outboard-motor-mounted microcomputer33(Refer to (2-1) and (2-3)). Thus, controllability of trim and tilt angles of the outboard motor13can be improved by giving precedence in boat control to the first steering station15A, and during maintenance, for example, trim and tilt angle control of the outboard motor13from the outside of the outboard motor13can be improved.

With continued reference toFIG. 5, when the operation instruction is input by the second PTT switch47only, the first microcomputer27can cut off the operation instruction without sending it to the outboard-motor-mounted microcomputer33(Refer to (2-2)). Thus, adverse effects on the trim and tilt angle control of the boat propulsion unit can be avoided by the second steering station not having precedence in boat control.

When the operation instructions are input simultaneously by the first PTT switch46and the second PTT switch47, or by the third PTT switch48and the second PTT switch47, the first microcomputer27can transmit only the operation instructions by the first and third PTT switches46,48to the outboard-motor-mounted microcomputer33(Refer to (2-4), (2-6)). Thus, the implementation of trim and tilt angle control by the operation instruction from the second steering station15B, which does not have precedence in boat control, can be prevented, as such operation instruction is not intended by a boat operator or a helmsman. In addition, controllability of the trim and tilt angle of the outboard motor13can be improved further by the first steering station15A having precedence in boat control, or by the control of the outboard motor13provided from the outer surface.

With continued reference toFIG. 5, when the operation instruction is input simultaneously by the first PTT switch46and the third PTT switch48, the first microcomputer27can cut off both operation instructions transmitted by the first and the third PTT switches46,48, without transmitting any operation instruction to the outboard-motor-mounted microcomputer33(Refer to (2-5)). Thus, when the conflicting operation instructions are input simultaneously to the outboard-motor-mounted microcomputer33from the outboard motor13and the first steering station15A, which has precedence in boat control, trim and tilt angle control that was essentially not intended by a boat operator or a helmsman can be prevented.

Note that electric power from the main battery34aand the sub battery34bcan be supplied to the first microcomputer27or related devices while the main switch43ais ON. Therefore, unlike the aforementioned cases fromFIG. 5in which the main switch43A is OFF, the first microcomputer27can function without power being supplied by the 5V power supplies36a,36b.

Information relating to a relationship between the operation instruction input and the operation instruction output when the main switch43ais ON and the operating station selector switch44B on the second key switch assembly24is ON can be stored in a third table27d3as shown inFIG. 6.

In this case, the prioritization regarding the operation instructions from the first PTT switch46and those from the second PTT switch47can be inverted from the cases stored in the first table27d1and the second table27d2. Specifically, equal priority can be given to the operation instructions from the second PTT switch47and those from the third PTT switch48, while lower priority is given to the operation instructions from the first PTT switch46relative to those from the second and the third PTT switches47,48.

In this case, too, when the operation instruction is input by the first, second, or third PTT switch46,47, or48, the DBW microcomputer27aof the first microcomputer27can identify the PTT switch from which the operation instruction came, and check which steering station, e.g., the first steering station15A or the second steering station15B, has precedence in boat control. Then, the DBW microcomputer27acan refer to the information stored in the third table27d3, and determine which operation instruction is to be transmitted to the outboard-motor-mounted microcomputer33, or that all of the operation instructions are to be cut off.

With continued reference toFIG. 6, when the operation instruction is input by the second PTT switch47only, or by the third PTT switch48only, the first microcomputer27can transmit the relevant operation instruction to the outboard-motor-mounted microcomputer33(Refer to (3-2) and (3-3)). Thus, controllability of trim and tilt angles of the outboard motor13can be improved by the second steering station15B having precedence in boat control, and during maintenance, for example, controllability of trim and tilt angle of the outboard motor13from the outside of the outboard motor13can be improved.

When the operation instruction is input by the first PTT switch46only, the first microcomputer27can cut off the relevant operation instruction without sending it to the outboard-motor-mounted microcomputer33(Refer to (3-1)). Thus, adverse effects on the trim and tilt angle control of the boat propulsion unit can be avoided by the first steering station not being given precedence in boat control.

When the operation instructions are input simultaneously by the second PTT switch47and the first PTT switch46, or by the third PTT switch48and the first PTT switch46, the first microcomputer27can cut off the operation instruction by the first PTT switch46, and transmit the operation instructions by the second and third PTT switches47,48to the outboard-motor-mounted microcomputer33(Refer to (3-4), (3-5)). Thus, the implementation of trim and tilt angle control by the operation instruction from the first steering station15A, which does not have precedence in boat control, can be prevented, as such operation instruction is not intended by a boat operator or a helmsman. In addition, controllability of trim and tilt angles of the outboard motor13can be improved further by the second steering station15B being given precedence in boat control, or by the control of the outboard motor13provided from the outer surface.

When the operation instructions are input simultaneously by the second PTT switch47and the third PTT switch48, the first microcomputer27can cut off both operation instructions transmitted by the second and the third PTT switches47,48, without transmitting any operation instruction to the outboard-motor-mounted microcomputer33(Refer to (3-6)). Thus, when conflicting operation instructions are input simultaneously to the first microcomputer27from the outboard motor13and the second steering station15B, which has precedence in boat control, trim and tilt angle control that was not intended by a boat operator or a helmsman can be prevented.

Note that electric power from the main battery34aand the sub battery34bcan be supplied to the first microcomputer27while the main switch43ais ON. Therefore, first microcomputer27can function without power being supplied from the 5V power supplies36a,36b.

As described in the preceding paragraphs, the first PTT switch46, the second PTT switch47, and the third PTT switch48can be prioritized in the processing described above, and the operation instructions can be processed in accordance with the prioritization. Thus, the operation instructions transmitted by each of the PTT switches46,47,48can be processed based on the predetermined priority. Thus, the controllability of trim and tilt angles of the boat propulsion unit or units can be improved by controlling the transmission of the operation instructions from the first, second, and third PTT switches46,47,48to the outboard-motor-mounted microcomputer33based on the mounting location of the first, second, and third PTT switches46,47,48(e.g., the first steering station15A, the second steering station15B, or a location outside of the hull12), as well as the status of the boat10(e.g., whether the first steering station15A or the second steering station15B has precedence in boat control, and whether maintenance is being performed on the boat10).

Thus, the operation instructions transmitted by the plural operation instruction output means can be processed based on the predetermined priority. This allows control over the transmission of operation instructions coming from the plural PTT switches and being sent to the boat propulsion unit, in accordance with the mounting location of the PTT switches and the status of the boat to attain improved controllability of the trim and tilt angles of the boat propulsion unit.

The present inventions can be applied to the boat10having one outboard motor13and two steering stations, as described above, however, this structure is not limiting. A boat equipped with two or more outboard motors, or a boat equipped with three or more steering stations can also be used. Such an embodiment can include additional PTT switches, and may include predetermined priorities for each PTT switch.

Also the propulsion unit of the boat can be the outboard motor13as described above, however, a boat equipped with other types of boat propulsion unit such as stern drives can also be used.

The third PTT switch48can be provided on the outer surface of the outboard motor13as described above, however, the third PTT switch can be installed in other locations such as on the side of the hull12where it can be controlled easily during maintenance.