Watercraft steering mechanism and trimmer

Abstract

A method for controlling a watercraft with a steering wheel, a steering device and twin motors, the method includes: maneuvering the watercraft at a first speed using side thrusters, controllable pitch propellers, or side thrusters with a deflection device as the steering device, wherein, when the watercraft travels in reverse and the watercraft makes a turn at the first speed, the steering wheel and the watercraft turn in a same direction, and maneuvering the watercraft at a second speed higher than the first speed using the controllable pitch propellers as the steering device, wherein, when the watercraft makes a turn at the second speed, a constant speed is maintained for both of the twin motors.

Description

BACKGROUND

This is a Continuation of application Ser. No. 11/989,482 filed Feb. 8, 2008, which in turn is a National Phase of Application No. PCT/CH2006/000412 filed Aug. 4, 2006, which claims the benefit of Application No. CH 1306/05 filed Aug. 8, 2005. The disclosure of the prior application is hereby incorporated by reference herein in its entirety.

The invention involves the control of a watercraft using steering and trimming equipment.

For thousands of years, the preferred method of steering watercraft has been achieved by using rudders, which may consist of one or several surfaces. Since the arrival of small outboard motors and drives as described in DE 1 025 293, certain watercraft are directly controlled by a propeller. More recently, various refined systems have been developed, in particular for faster watercraft, using a trim wedge steering known as a Humphree systems or two parallel held stern drives, for example, as described in WO 03/093102. Trim tabs are used to improve the planing angle on watercraft, to correct poor weight distribution, and to alter the buoyancy areas using flow deflectors in order to bring a watercraft more quickly into the planing position as described in U.S. Pat. No. 3,628,487.

SUMMARY

The invention involves a simplified but effective method of steering, which is efficient even under the influence of wind and current. The invention also involves an automatically and rapidly acting trimming operation for the vessel using trim tabs, which can be used in conjunction with the steering system.

When navigating slowly in a harbor, for example, the steering rudder surfaces react poorly because of poor water flow on the rudder profiles. The drive units of the stern drives or surface piercing propeller drives also have extremely limited maneuverability. As a result, for the purposes of this invention, under a pre-determined speed the system is automatically switched over to the more efficient control characteristics of a side thruster where the thrust is dependent upon the position of the steering wheel. In addition, when switching to reverse, the direction of the thrust of the side thruster is reversed so that, for a given steering wheel position of the watercraft, the side thruster is correctly positioned when the watercraft moves in the reverse direction. A further improvement to the steering is the utilization of a controllable pitch propeller on twin drives, by which the pitch of the propeller can be set in forward thrust and the other propeller in reverse thrust, where the difference in pitch of both propellers to each other is dependent upon the position of the steering wheel, as well as upon the detected speed of the watercraft.

The main aim of the invention is to guarantee optimal steering at any speed without rudders or a complex propeller shaft mechanism, and at the same time to reduce as much as possible the steering mechanism resistance in the water at higher speeds as well as improving reversing operations of the watercraft in harbors and to facilitate trim during the acceleration phase.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary aspects of the invention will be described with reference to the drawings, wherein:

FIG. 1 shows a schematic view of a watercraft with a steering wheel fitted to a steering column;

FIG. 2 shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting lever in the forward position;

FIG. 3 shows a schematic view of the watercraft with a steering wheel turning to the left and the shifting lever in the forward position;

FIG. 3a shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting lever in the reverse position;

FIG. 4 shows a schematic view of a watercraft with a steering wheel mounted on a steering column;

FIG. 5 shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting lever in the forward position;

FIG. 5a shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting lever in the reverse position;

FIG. 6 shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting lever in the forward position;

FIG. 6a shows a schematic view of a watercraft with the steering wheel turning to the left and the shifting lever in the reverse position;

FIG. 6b shows a schematic view of a watercraft in a 180° turn in the travel condition as described in FIGS. 6 and 6a;

FIG. 7 shows a schematic view of a watercraft with a steering wheel turning to the left and the shifting level in the forward position;

FIG. 8 shows an isometric view of a steering flap with a curved flow deflector;

FIG. 9 shows a schematic side section through a composite steering flap;

FIG. 10 shows a schematic side cross section through a composite steering flap in the steering position in accordance with FIG. 9; and

FIG. 11 shows a schematic side cross section of a dual plate in accordance with FIG. 9 in the trim operation position.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic view of a watercraft 1 with a steering wheel 2 fitted to a steering column. A stroke measuring unit 3 (which can be an angle measuring device, an eccentric lift sensor or a positional switch) delivers a steering reading 3a to a controller 4 which passes on a signal 4a to the hydraulic system 5 in order to open the appropriate control valve 6. As a result, the controllable pitch propeller 8 (which is an example of a steering device) can be operated via the hydraulic line 5a and the steering flap 10 can be operated via the hydraulic line 5b in order to execute the required movement by means of an activator 7 and a steering activator 16. The activator 7 and the steering activator 16 have a stroke measuring unit 3, which sends steering readings 3b back to the controller 4 in order to carry out an actual value versus nominal value comparison. That is, the controller 4 determines if the steering flap 10 and controllable pitch propeller 8 are operated a sufficient amount (actual value) based on the amount by which the steering wheel 2 turns (nominal value). The hydraulic system 5 and the control valve 6 work until the steering flap 10 and controllable pitch propeller 8 are appropriately positioned. Thus, the activator 7 can control a controllable pitch propeller 8 to displace the blade 9, the steering activator 16 and the steering flap 10. Furthermore, the steering depends upon the speed component 11 of the watercraft 1 which is relayed to the controller 4 via the speed measuring reading 11a.

The measurable speed of the watercraft 1 can be processed by the controller 4 using, for example, the detected revolutions of the motors as a measured value, the detected revolutions of the controllable pitch propeller 8 multiplied by a blade pitch of the controllable pitch propeller 8, a global positioning system and the like. Control of the activator 7 depends upon the position of the shifting lever 12. The position of the shifting lever 12 is sent to the controller 4 via a signal 3c. Whether a neutral position N, a forward position F, a reverse position R or a completely shut down system NO was selected is taken into account by the controller 4. It is understood that a steering change does not only refer to the hydraulic system 5 but a pneumatic version is also possible with the limitation that only locking activators may be used that lock the selected position so that compressibility of the compressed air due to pressure fluctuations can have no effect on the position of the propeller blade 9 or the steering flaps 10. In addition, a steering change can be effected electrically with the activator 7 being an electric motor. With twin drives, the controller 4 also has the task of synchronizing the speed components 11 of both motors, whereby the stroke measuring unit 3 of the shifting lever 12 is also included as a reading. Where necessary, the shifting lever 12 can be coupled to the throttle to form a single unit.

FIG. 2 shows a schematic view of a watercraft 1 with a steering wheel 2 and a steering angle to the left (to port), and the shifting lever 12 in the forward position F. The steering angles determined via the stroke measuring unit 3 are relayed to the controller 4. At the same time, the controller 4 records the speed component 11 of the watercraft 1 and the position of the shifting lever 12, whereby a speed of the watercraft 1 is recorded. This permits the controller 4 to select a planing mode program and, via the hydraulic system 5, to operate the activator 7 to enable the left side controllable pitch propeller 8 to reduce its propeller pitch. This allows the watercraft 1 to turn to the left because the thrust on the right side controllable pitch propeller 8 remains steady while the thrust on the left side controllable pitch propeller 8 is reduced. The arrows PS show the thrust differential of both controllable pitch propellers 8. At high speeds, the propeller blades 9 do not produce any backward thrust. It is also feasible that the right side controllable pitch propeller 8 can produce more thrust, whereby care should always be taken to ensure that the controller 4 maintains both motor revolutions at a constant speed (maintaining a constant speed for both of the twin motors) so that, when moving along a curved path, there are no undesirable changes in motor speed.

FIG. 3 shows a schematic view of the watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the forward position F. The steering angle and the control is identical to that shown in FIG. 2, whereby, in this case, the controller 4, due to a reduced speed detected by the speed component 11, has selected a program for when the watercraft 1 moves at a slow speed (a first speed lower than a second speed) (as is the practice in harbor maneuvers). In doing so, with a full turn for example to the left, the left side controllable pitch propeller 8 is turned to a maximum reverse thrust position so that a negative thrust of the controllable pitch propeller 8 can be produced, which has more of a turning effect than just one small but positive blade pitch at the left side controllable pitch propeller 8. The arrows illustrate the thrust forces PS. As long as the propeller thrust PS of the right side controllable pitch propeller 8 is greater than that of the left side controllable pitch propeller 8, the watercraft 1 will turn left. In other words, when the steering wheel 2 is turned to a port side of the watercraft 1 and the watercraft 1 moves in a forward direction as illustrated in FIG. 3, a port side controllable pitch propeller (left side controllable pitch propeller 8) reduces pitch and a starboard side controllable pitch propeller (right side controllable pitch propeller 8) increases pitch in the forward direction. As should be appreciated, when the steering wheel 2 is turned to a starboard side of the watercraft 1 and the watercraft 1 moves in the forward direction, the starboard side controllable pitch propeller reduces pitch and the port side controllable pitch propeller increases pitch in the forward direction.

FIG. 3a shows a schematic view of a watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the reverse position R. The steering angle is identical to that shown in FIG. 3, whereby, in this case, when going from the forward position F to the reverse position R, the propeller blades 9 are turned, so that the propeller thrust PS of the right side controllable pitch propeller 8 is shown in a negative reverse direction. The left side controllable pitch propeller 8 having less thrust in the backwards direction or is completely in the forward direction, so that the watercraft 1 travels backwards, and, when viewed in the direction of travel, turns to the right like a car (left when viewing FIG. 3a) with the same steering movement having the same effect. In other words, when the steering wheel 2 is turned to a port side of the watercraft 1 and the watercraft 1 moves in a reverse direction as illustrated in FIG. 3a, a port side controllable pitch propeller (left side controllable pitch propeller 8) reduces pitch and a starboard side controllable pitch propeller (right side controllable pitch propeller 8) increases pitch in the reverse direction. As should be appreciated, when the steering wheel 2 is turned to a starboard side of the watercraft 1 and the watercraft 1 moves in the reverse direction, the starboard side controllable pitch propeller reduces pitch and the port side controllable pitch propeller increases pitch in the reverse direction. A slight movement of the steering wheel 2 leads to a minimal pitch differential of the propeller blades 9. Each increase in the steering wheel angle leads to an increase of the pitch difference of the controllable pitch propellers 8. In the neutral position N, the watercraft 1 can be turned on its vertical axis. For this, the propeller blades 9 are brought into an opposite pitch so that the thrust forces of both controllable pitch propellers 8 are identical, but acting in the opposite direction.

FIG. 4 shows a schematic view of a watercraft 1 with a steering wheel 2 mounted on a steering column, which via a stroke measuring unit 3 (which, for example, can be an angle measuring device, an eccentric lift sensor or a positional switch), relays the steering reading 3a to a controller 4, which relays the signal 4a to the hydraulic system 5 for the purposes of opening the control valves 6 which could preferable be proportional valves. Via the hydraulic line 5c, the hydraulic motors 15 drive the bow thruster 13 and the stern thruster 14. It is advantageous that, with an increased steering angle of the steering wheel 2, the revolutions of the hydraulic motors 15 are increased so that the thrust of the thrusters 13, 14 is increased accordingly. If the thrusters 13, 14 are equipped with a controllable pitch propeller, then the steering angle of the steering wheel 2 can have a direct influence on the propeller pitch of the thrusters 13, 14. Furthermore the controller 4 checks the speed component 11, since both thrusters 13, 14 are activated only below a certain speed. The position of the shifting lever 12 is a further input factor and is similarly taken into account by the controller 4, where the shifting lever 12 has a stroke measuring unit 3 and the signal 3c, which indicates the position of the shifting lever 12 as to whether it is in the neutral N, forward position F or reverse position R. It is to be understood that the thrusters 13, 14 not only involve the hydraulic system 5, but that it can be either pneumatically controlled or driven by an electric motor.

FIG. 5 shows a schematic view of a watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the forward position F. The steering angle determined via the stroke measuring unit 3 is transmitted to the controller 4. At the same time, the controller 4 records the speed component 11 of the watercraft 1 and the position of the shifting lever 12. In this case, the reduced speed (which is used in harbors) is recognized due to the speed component 11, and using a full turn of the wheel to the left, for example, the hydraulic motor 15 of the stern thruster 14 (i.e., side thruster, which is an example of a steering device) is activated. The effect of this is that a side thrust, indicated by arrow QS, is directed to the right and the watercraft 1 turns to the left. The larger the steering wheel angle of the steering wheel 2, the greater the side thrust QS of the stern stern thruster 14.

FIG. 5a shows a schematic view of a watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the reverse position R. The steering angle is identical to the steering angle in FIG. 5 whereby, in this case, when shifting from the forward direction to the reverse direction, the thrust of the stern thruster 14 is activated in the opposite direction, as shown by the arrow QS, so that the watercraft 1 seen in the direction of travel, as shown by arrow PS, turns right (left when viewing FIG. 5a) as happens when steering a vehicle, having the same effect as an automobile.

FIG. 6 shows a schematic view of a watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the forward position F. The steering input is identical to that shown in FIG. 5 whereby, in this case, an additional bow thruster 13 is activated whose side thrust shown by the arrow QS is opposite to the side thrust of the stern thruster 14. A steering angle for example to the left produces a side thrust QS at the stern thruster 14 to the right. At the same time, it produces a side thrust at the bow thruster 13 to the left. The greater the steering wheel angle to the steering wheel, the greater the side thrust of both thrusters 13, 14. In other words, when the steering wheel 2 is turned to a port side of the watercraft 1, the watercraft 1 moves in a forward direction and the bow thruster 13 is activated as illustrated in FIG. 6, the bow thruster 13 exerts a thrust to starboard. As should be appreciated, when the steering wheel 2 is turned to a starboard side of the watercraft 1, the watercraft 1 moves in the forward direction and the bow thruster 13 is activated, the bow thruster 13 exerts a thrust to port.

FIG. 6a shows a schematic view of a watercraft 1 with the steering wheel 2 turning to the left and the shifting lever 12 in the reverse position R. The steering angle is identical to that shown in FIG. 5 whereby, in this case, the side thrust of the bow thruster 13 and the stern thruster 14 are in opposite directions, so that the watercraft 1 facing in the direction of travel and indicated by the arrow PS turns to the right (left when viewing FIG. 6a) as when steering an automobile, having the same effect as an automobile. In other words, when the steering wheel 2 is turned to a port side of the watercraft 1, the watercraft 1 moves in a reverse direction and the bow thruster 13 is activated as illustrated in FIG. 6a, the bow thruster 13 exerts a thrust to port. As should be appreciated, when the steering wheel 2 is turned to a starboard side of the watercraft 1, the watercraft 1 moves in the reverse direction and the bow thruster 13 is activated, the bow thruster 13 exerts a thrust to starboard. If the watercraft 1 does not undertake a movement in the forward direction and the reverse direction, then the watercraft 1 can be turned on its vertical axis in the neutral position N since, in this position, there is no propeller thrust PS but the steering angle still activates the thrusters 13, 14. Moving the shifting lever 12 to NO (not pictured) disengages all steering and control activities. The propeller is also mechanically disengaged, although in the neutral position it continues to turn without producing any thrust.

FIG. 6b shows a schematic view of a watercraft in a 180° turn with radius Ra in the travel condition as described in FIGS. 6 and 6a. The steering angle is constant, only in the forward direction is the thrust of the bow thruster 13 activated to the left in the reverse direction, the thrust of the bow thruster 13 is activated to the right and the stern thruster 14 reacts in the opposite direction so that the watercraft 1 can be driven in a circle forwards and backwards without altering the steering wheel angle.

FIG. 7 shows a schematic view of a watercraft 1 with a steering wheel 2 turning to the left and the shifting lever 12 in the forward position F. The steering angle derived from the stroke measuring unit 3 is relayed to the controller 4. At the same time, the controller 4 records the speed component 11 of the watercraft 1 and the position of the shifting lever 12, whereby, in this case, the speed of the watercraft 1 is recorded. This permits the controller 4 to select the planing mode and give instructions to the hydraulic system 5, as described in FIGS. 1 and 2. In this case, the steering activator 16 operates the left steering flap 10 so that it is lowered into the water. The effect of this is that the water flow WS is directed by the steering flap 10 (that is, deflection device) and is deflected in order to produce a side thrust SS on the left side of the watercraft 1, whereby resistance RR occurs which causes the watercraft 1 to turn to the left. The greater the steering wheel angle to the steering wheel 2, the deeper the steering flap 10 lowers into the water, the greater the side thrust SS and the greater the resistance RR.

The programmed reduced speed or planing mode, and the associated activation of the thrusters 13, 14 or of the steering flap 10 do not need to be fixed speed settings, but can be flexible as well. Switching off one or the other steering modes, whereby the steering activator 16 or motor 15 are not permanently activated together, is highly desirable because of the energy saved which can be used to increase the pressure of the hydraulic system 5. The combination of the thrusters 13, 14 with a steering flap 10 or a dual plate 21 is feasible. Even a normal thruster, which at slow speeds produces very little control pressure, can benefit from an automatic reversal of the thrusters 13, 14.

FIG. 8 shows an isometric view of a steering flap 10 with a curved flow deflector 17, whereby any shape and skewing of the flow deflector 17 is permitted, which influences the lateral side thrust. A cover 18 connects the flow deflector 17 with the guide rails 19 to lower the steering flap 10 into the water flow and serves to secure the bracket 20 for the steering activator 16 and also serves as a deflector for water that is sprayed. Of course, the bracket 20 may also be directly fitted to the guide rails 19.

FIG. 9 shows a schematic side section through a dual plate 21, which at the same time can be used as a steering flap 10 and a trim tab 22, with two independent activators each being equipped with a stroke measuring unit 3, a steering activator 16 and a trim activator 23 to trim the watercraft 1. The design of the steering flap 10 includes a bottom lip 24 so that the water flow WS is channeled and the lateral transverse thrust SS is also increased. In extreme cases, the channel K can consist of a curved pipe in order to deflect the water flow accordingly. The dual plate 21 is held by a longitudinal guide 25, which is fixed to the dual plate frame 26. The dual plate frame 26 is secured to the watercraft 1. By means of a pivot bearing, the steering flap 10 or the trim tab 22 can be lowered individually or together. The dual plate 21 is lowered by turning the steering wheel 2. The greater the turn, the deeper the dual plate 21 lowers into the water. The trim tab 22 is automatically lowered in the start phase, and fine adjustment of the trim tab 22 is carried out manually by an activator (not shown) on the steering column of the watercraft 1.

FIG. 10 shows a schematic side cross section through a dual plate 21 in the steering position in accordance with FIG. 9. The water flow WS is diverted into channel K and at the same time the water resistance RR is increased by the introduction into the water of the steering flap 10 on one side, which makes the watercraft 1 turn.

FIG. 11 shows a schematic side cross section of a dual plate 21 in accordance with FIG. 9 in the trim operation position. The water flow WS is activated by lowering the trim tab 22 which produces an upward force LK on watercraft 1. It is also feasible that the steering activator 16 can be lowered by the thickness of the bottom lip which leads to resistance similar to trim wedge steering, which similarly releases an upward force on the watercraft 1, and the trim activator 23 is lowered at the same time.

The controller 4 calculates the watercraft speed using the speed component 11, and the shifting lever 12, which can be coupled with the motor throttle (not shown) and attached to the stroke measuring unit 3, thus can be used for automatic trim tab control. For example, the speed determines how quickly the shifting lever 12 together with the coupled throttle is pushed forward. This leads to a signal that is relayed to the hydraulic system 5, the control valve 6 and the hydraulic accumulator 28, so that the trimming activator 23 is activated and the trim tab 22 is instantly lowered. The involvement of the hydraulic accumulator 28 ensures that there is sufficient pressure available to supply the trim tab 22 with oil as quickly as possible. When the watercraft 1 picks up speed, the trim tab 22 is continually returned to its starting position. The effect of this is that when the watercraft 1 is started in the bow of the watercraft 1, the watercraft 1 does not lift excessively due to the fact that the trim tab 22 extends immediately. As soon as the watercraft 1 reaches a defined speed, the trim tab 22 is retracted whereby the reaction process can occur continually. The trim tab 22 setting in this operation occurs simultaneously and in parallel.

Claims

1. A method for controlling a watercraft with a steering wheel, a steering device and twin motors, the method comprising:

maneuvering the watercraft at a first speed using side thrusters, controllable pitch propellers, or side thrusters with a deflection device as the steering device, wherein, when the watercraft travels in reverse and the watercraft makes a turn at the first speed, the steering wheel and the watercraft turn in a same direction, and

maneuvering the watercraft at a second speed higher than the first speed using the controllable pitch propellers as the steering device, wherein, when the watercraft makes a turn at the second speed, a constant speed is maintained for both of the twin motors.

2. The method in accordance with claim 1, wherein:

the watercraft maneuvers at the first speed using the side thrusters as the steering device, and

a steering angle of the steering wheel determines a transverse thrust of the side thrusters.

3. The method in accordance with claim 2, wherein:

the side thrusters include a bow side thruster,

when the steering wheel is turned to a port side of the watercraft, the watercraft moves in a forward direction and the bow side thruster is activated, the bow side thruster exerts a thrust to starboard, and

when the steering wheel is turned to a starboard side of the watercraft, the watercraft moves in the forward direction and the bow side thruster is activated, the bow side thruster exerts a thrust to port.

4. The method in accordance with claim 1, wherein:

the watercraft maneuvers at the first speed using the side thrusters as the steering device, and

the side thrusters are not activated above a predetermined speed.

5. The method in accordance with claim 1, wherein the watercraft maneuvers at the first speed using the controllable pitch propellers as the steering device.

6. The method in accordance with claim 5, wherein:

when the steering wheel is turned to a port side of the watercraft and the watercraft moves in a forward direction, a port side controllable pitch propeller reduces pitch and a starboard side controllable pitch propeller increases pitch in the forward direction, and

when the steering wheel is turned to a starboard side of the watercraft and the watercraft moves in the forward direction, the starboard side controllable pitch propeller reduces pitch and the port side controllable pitch propeller increases pitch in the forward direction.

7. The method in accordance with claim 5, wherein revolutions of the twin motors are electronically controlled so that the revolutions of the twin motors remain constant at the second speed when the steering wheel is turned and one of the controllable pitch propellers is displaced.

8. The method in accordance with claim 5, wherein a position of propellers of the controllable pitch propellers is dependent upon a speed of the watercraft, a position of a reverse lever that indicates a direction that the watercraft travels and a steering angle position of the steering wheel.

9. The method in accordance with claim 5, wherein the controllable pitch propellers are attached to a path measuring unit that sends a measured value to a controller for a nominal value versus an actual value comparison in order to appropriately position the controllable pitch propellers.

10. The method in accordance with claim 8, wherein a speed of the watercraft is measured using at least one of revolutions of twin motors, revolutions of the controllable pitch propellers multiplied by propeller pitch, or a global positioning system, that is relayed to a controller.

11. The method in accordance with claim 1, wherein measuring units are fitted to a shifting lever that indicates a direction that the watercraft travels, and an activator and a steering activator the controls a movement of the watercraft.

12. The method in accordance with claim 7, wherein the controllable pitch propellers do not produce a backward thrust when the steering wheel is turned at the second speed.

13. The method in accordance with claim 1, wherein a direction of thrust of the steering device is reversed when the watercraft switches a travel direction from a forward direction to a reverse direction and the steering wheel remains turned in a same direction.

14. The method in accordance with claim 2, wherein:

the side thrusters include a bow side thruster,

when the steering wheel is turned to a port side of the watercraft, the watercraft moves in a reverse direction and the bow side thruster is activated, the bow side thruster exerts a thrust to port, and

when the steering wheel is turned to a starboard side of the watercraft, the watercraft moves in the reverse direction and the bow side thruster is activated, the bow side thruster exerts a thrust to starboard.

15. The method in accordance with claim 5, wherein:

when the steering wheel is turned to a port side of the watercraft and the watercraft moves in a reverse direction, a port side controllable pitch propeller reduces pitch and a starboard side controllable pitch propeller increases pitch in the reverse direction, and

when the steering wheel is turned to a starboard side of the watercraft and the watercraft moves in the reverse direction, the starboard side controllable pitch propeller reduces pitch and the port side controllable pitch propeller increases pitch in the reverse direction.