WO2006062416A1

WO2006062416A1 - Propulsion and control system for a marine vessel

Info

Publication number: WO2006062416A1
Application number: PCT/NZ2005/000319
Authority: WO
Inventors: Andrew John Ashby; John Robert Borrett
Original assignee: Cwf Hamilton & Co Limited
Priority date: 2004-12-07
Filing date: 2005-12-07
Publication date: 2006-06-15
Also published as: AU2005312429A1; EP1827969A1

Abstract

A propulsion and control system for a marine vessel comprises one or more waterjet units and optionally one or more lateral thrusters a control device, and a manually moveable control element which is rotatable about an axis and moveable in a plane and an associated control system arranged to operate the waterjet unit(s) and lateral thruster(s) to manoeuvre the vessel in accordance with the movement of the control element. Displacement of the control element in the plane will cause a corresponding rate of movement for the vessel in the direction in which the control element is moved, and rotation of the control element, either clockwise or anticlockwise, will cause yaw of the vessel about a vertical axis.

Description

PROPULSION AND CONTROL SYSTEM FOR A MARINE VESSEL

FIELD OF THE INVENTION

The present invention relates to a propulsion and control system for a marine vessel.

BACKGROUND TO THE INVENTION

A number of different control systems may be used to control the movement of a marine vessel that is propelled by one or more waterjet units. The magnitude and direction of the net thrust vector produced by a waterjet is a function of the throttle setting of the engine driving the waterjet, the position of the reverse deflector and the angle of the steering deflector or nozzle. Traditionally, one or more control levers are used to control the position of the waterjet reverse duct(s) and the throttle setting of the engine(s) driving the waterjet unit(s), while a helm wheel is used to control the position of the steering deflector(s) or nozzle(s) of the waterjet unit(s). Thus the surge, sway and yaw of the vessel may be controlled at both high and low speeds via operation of the control lever(s) and helm wheel together in various combinations.

More recently, joystick control devices have been incorporated into the control systems of waterjet vessels to provide an alternative means of manoeuvring, particularly for low speed operations such as docking and setting off. For example, International PCT Patent Publication No. WO 01/34463 describes a control system which in one embodiment utilises the combination of a dual axis joystick and helm wheel for manoeuvring a boat driven by twin waterjet units, and US Patent No. 6,386,930 describes a control system which utilises a 3 -axis joystick.

Bow and stern thrusters may also be installed in vessels to enhance manoeuverability when docking and setting off. The bow and stern thrusters can be controlled by joystick or other control devices as described in US Patent No. 6,538,217. WO98/25194 also discloses a three axis control device for a marine vessel. It is an object of the present invention to provide an improved or at least alternative control system for manoeuvring a marine vessel.

SUMMARY OF THE INVENTION

In a first aspect, the present invention broadly consists of a propulsion and control system for a marine vessel comprising: two or more waterjet units for propelling the vessel; a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane; and an associated control system arranged to operate the waterjet units to manoeuvre the vessel in accordance with movement of the control element.

In a second aspect, the present invention broadly consists of a propulsion and control system for a marine vessel comprising: two or more waterjet units for propelling the vessel: a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane over a reference surface below the control element; and an associated control system which operates the waterjet units to manoeuvre the vessel in accordance with the movement of the control element.

Preferably, the control system operates the waterjet units so that displacement of the control element in the plane causes a corresponding rate of movement for the vessel in the direction in which the control element is moved, and rotation of the control element, either clockwise or anticlockwise, causes yaw of the vessel about a vertical axis.

Preferably, the control system generates signals which actuate the steering deflectors and reverse ducts of the waterjet units and the engine throttles.

The control element in at least one mode may be biased toward a neutral position with respect to both movement in the plane and also rotation. The control system is arranged to operate the waterjet units at zero thrust when the control element is in a neutral position.

Typically the vessel has at least one port waterjet unit and at least one starboard waterjet unit. The control system is preferably arranged to actuate the steering deflectors of the waterjet units in synchronism, while the reverse ducts of the waterjet units may be actuated in synchronism or differentially.

Preferably, the control system is arranged such that increasing displacement of the control element from a neutral position increases thrust for translational movements of the vessel. Similarly, the angle of rotation from the neutral position corresponds to the rate of yaw desired.

The control element is operable by a user's hand and may be vessel-shaped or have a shape which is representative of a marine vessel. Alternatively, the control element may be shaped like a computer mouse or otherwise to fit in the hand of an operator.

Preferably, the control element is rotatable about an axis perpendicular to the plane, and which will typically be a vertical axis.

Preferably, the control device is arranged such that the movement of the control element is restricted to a defined area.

hi a third aspect, the present invention broadly consists in a propulsion and control system for a marine vessel comprising: one or more waterjet units and one or more lateral thrusters; a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane; and an associated control system arranged to operate the waterjet unit(s) and lateral thruster(s) to manoeuvre the vessel in accordance with the movement of the control element. In a fourth aspect, the present invention broadly consists in a propulsion and control system for a marine vessel comprising: one or more waterjet units and one or more lateral thrusters comprising: a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane over a reference surface below the control element; and an associated control system which operates the waterjet unit(s) and lateral thruster(s) to manoeuvre the vessel in accordance with the movement of the control element

The marine vessel may be propelled by one or more waterjet units and have at least one lateral bow thruster. The control system operates the waterjet unit(s) and bow thruster so that displacement of the control element in the plane causes a corresponding rate of movement for the vessel in the direction in which the control element is moved, and rotation of the control element, either clockwise or anticlockwise, causes yaw of the vessel about a vertical axis.

Preferably, the control system generates signals which actuate the steering deflector and reverse duct(s) of the waterjet unit(s), the engine throttle and the motor of the bow thruster.

The control element in at least one mode may be biased toward a neutral position with respect to both movement in the plane and rotation. The control system is arranged to operate the waterjet unit(s) and bow thruster at zero thrust when the control element is in a neutral position.

Preferably, the control system is arranged such that increasing displacement of the control element from a neutral position increases thrust for translational movements of the vessel. Similarly, the angle of rotation from the neutral position corresponds to the rate of yaw desired. Preferably, the control element is operable by a user's hand and may be vessel-shaped or have a shape which is representative of a marine vessel. Alternatively, the control element may be shaped like a computer mouse or otherwise to fit in the hand of an operator.

In any of the aspects of the invention described above, the control device may further comprise one or more additional manually operable control inputs for changing the relationship between the control element movement and the thrust response from the waterjet(s). For example, the additional control input may be in the form of a thumbwheel embedded in the control element.

The control device may be switchable between a low speed mode suitable for controlling low speed manoeuvres and a cruise mode suitable for controlling vessel manoeuvres at higher speeds.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

The term 'comprising' as used in this specification and claims means 'consisting at least in part of, that is to say when interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. In this specification and the accompanying claims the term "vessel" is intended to include boats such as smaller pleasure runabouts and other boats, larger launches whether mono-hulls or multi-hulls, and larger ships. More generally, the control device of the invention may be suitable for any planing or displacement type vessels, regardless of their size, speed capabilities, and hull type.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Various forms of the invention will be described by way of example only and with reference to the drawings, in which:

Figure 1 is a perspective view of a control device of one form of propulsion and control system of the invention;

Figure 2 is a perspective view of the control device being operated;

Figure 3 is a perspective view of the structural components supporting the control element of the control device;

Figure 4 is plan view of the control device showing the control element in a full ahead position with slight rotation to port;

Figure 5 is a plan view of the control device showing the control element in a full port position with slight rotation to port;

Figure 6 is a perspective view of an alternative control element which is provided with an additional control input; Figures 7a-7c show graphically, by way of example only, how the additional control of Figure 6 may control gain, sensitivity and engine idle speed respectively;

Figure 8 is a schematic diagram of a possible arrangement of a propulsion and control system comprising twin waterjet units on a marine vessel;

Figure 9 shows a number of fundamental manoeuvres which are possible with the system of Figure 8;

Figure 10 shows a sideways manoeuvre to port for the twin waterjet unit shown in Figure 8;

Figure 11 shows a schematic diagram of a propulsion and control system comprising twin waterjet units and a bow thruster on a marine vessel;

Figure 12 shows a number of fundamental manoeuvres which are possible with the system of Figure 11, some of which use differential thrust;

Figure 13 shows a number of fundamental manoeuvres which are possible with the system of Figure 11 , none of which use differential thrust;

Figure 14 is a schematic diagram of a propulsion and control system comprising a single waterjet unit and a bow thruster on a marine vessel; and

Figure 15 shows a number of fundamental manoeuvres which are possible with the system of Figure 14. DETAILED DESCRIPTION OF EMBODIMENTS

A propulsion and control system of the invention may comprise a preferred form of control device now described for controlling the propulsion system including both the primary waterjet propulsion unit(s) and any lateral thruster(s) primarily during manoeuvring a marine vessel, boat, ship or the like at low speeds, such as docking or setting off. The control device is arranged to operate the vessel's propulsion units to control a range of vessel movements including surge, sway and yaw, or a combination thereof.

Referring to Figures 1 and 2, in the embodiment shown the control device 100 is provided with a housing 101 which supports a moveable control element 102. The control element 102 is moveable with three degrees of freedom and in particular is moveable within an X-Y plane and is rotatable, clockwise or anticlockwise, about a Z- axis. Generally, the Z-axis is perpendicular to the X-Y plane. The control element is also biased toward a neutral position with respect to both movement in the X-Y plane and rotation about the Z-axis. The control element 102 preferably has a shape representative of a vessel. That is the control element has an approximate hull shape including a bow end 102a and stern end 102b. At the same time the control element is shaped to enable it to be held comfortably by the hand of an operator and may for example comprise rubberised grip portions 102c on either side. Various other shapes of the control element which are at least approximately representative of a vessel including a sharper bow end and a stern end may be used. The control element 102 is spaced from the top cover 103 of the housing 101 so that the surface of the top cover 103 acts as a reference surface for the user when manipulating the control element. The control element 102 is close to the surface 103 which allows precise operation because the heel of the hand/or some fingers can be rested on the reference surface 103 for stability (as shown in Figure 2). In another embodiment the control element 102 may not be positioned immediately above an adjacent reference surface and for example the control element may be mounted to the top of a pillar adjacent which the operator may stand while holding and manipulating the control device. When holding the control element the operator senses the direction of movement being requested without having to look down at the controls or instrumentation. The control element fits in the hand in a natural position, and can also be securely gripped by an operator and can be held in a number of different ways, preventing strain in the hand and arm.

A control system associated with the control device 100 operates the vessel's propulsion unit(s) and/or any lateral thrusters to manoeuvre the vessel in accordance with displacement and/or rotation of the control element 102. In this specification the term "lateral thruster(s)" is intended to include both fixed thruster(s) such as a thruster mounted in the bow of the vessel (a bow thruster) which can apply thrust in fixed direction or directions namely port or starboard thrust, and similar fixed thruster(s) provided elsewhere for example at the stern of the vessel, and also thruster(s) provided for assisting in slow speed maneuvering of the vessel and which can be operated to vary the direction in which thrust is applied such as azimuthing thruster(s). In particular, the control system operates the vessel's propulsion unit(s) and/or lateral thruster(s) so that displacement or rotation of the control element 102 causes a corresponding rate of movement of the vessel. For example, relative to the neutral position, displacement of the control element 102 along the X-axis of the plane causes a corresponding fore or aft translational movement (surge) of the vessel, while displacement of the control element 102 along the Y-axis of the plane causes a corresponding port or starboard translational movement (sway) of the vessel. Rotation of the control element 102, clockwise or anticlockwise, about its Z-axis causes a corresponding yaw movement of the vessel. Further, the control device can be operated to perform any combination of surge, sway and yaw movements simultaneously to manoeuvre the vessel as desired.

In the embodiment shown by way of example in Figures 1 to 6, the control element 102 is mounted to a rotary potentiometer which protrudes through a shaped aperture 104 (shown in Figure 3) in top cover 103 of the housing 101. Referring to Figure 3, the rotary potentiometer 105 has a spring-to-center mechanism and is arranged to generate a Z-axis signal representing the rotation of the control element 102 about the Z-axis from the center (neutral position). The rotary potentiometer 105 is also provided with limiting stops which restrict its rotational movement to predetermined angles. The rotary potentiometer 105 is mounted to an upper plate 106 which is movably mounted for movement in the Y-axis direction. Below the upper plate 106a lower plate 107 is movably mounted for movement in the X-axis direction. The lower plate 107 is constrained to move in the X-axis by rollers 150 on either side of the lower plate 107. In the preferred embodiment shown two rollers 150 are provided on either side, and are mounted on spindle elements 151 which extend downwardly from the underside of top cover 103. The rollers have a grooved profile and the left and right (port and starboard) edges of the lower plate 107 engage into the groove profile of the rollers 150 on either side to retain the lower plate 107 but allow movement of the lower plate 107 in the X- axis. The upper plate 106 is mounted by a similar arrangement of rollers, but for movement in the Y-axis. The front and rear (fore and aft) edges of the upper plate 106 similarly engage the grooved profile of rollers 153 mounted on spindles 152 which extend upwardly from the fore and aft edge of the lower plate 107.

Rotary potentiometers 155 and 158 are provided, fixed to the base 109, which generate X-axis and Y-axis signals representative of the position along the X-axis and Y-axis of the lower plate 107 and upper plate 106 respectively. The rotary potentiometer 155 and 158 are both fixed to the lower plate 107. Arm 154 is fixed to the input shaft of rotary potentiometer 155 and the distal end of arm 154 comprises a pin (not shown) which is captured within groove 156 in the upper plate 106. The arrangement is such that as the upper plate 106 moves in the Y-axis (caused by movement of the control element 102 in the Y-axis by an operator), the arm 154 is caused to rotate rotating the input shaft of the rotary potentiometer 155. A similar arm 157 is fixed to the input shaft of rotary potentiometer 158 and a pin (not shown) on the distal end of arm 157 is captive in a groove 159 (not shown) in the underside of the top cover 103 so that the input shaft of the potentiometer 158 moves as the lower plate 107 moves in the X-axis, through operator movement of the control element 102. Spring mechanisms (not shown) are provided to bias the control element 102 toward a central position (neutral position) when it is not being operated. The rotary potentiometers 155 and 158 generate X-axis and Y-axis signals which represent the position of the control element 102 relative to the neutral position. As mentioned, the rotary potentiometer 105, onto which the control element 102 is mounted, protrudes through a shaped aperture 104 in a top cover 103 of the housing 101. Referring to Figure 4, the shaped aperture 104 is preferably generally diamond- shaped and restricts the movement of the control element 102 in the X-Y plane. This ensures limited sideways displacement (sway) when the control element 102 is in the full ahead (as shown in Figure 4) or full astern positions. Likewise, when the control element is fully to port (as shown in Figure 5) or starboard, the diamond-shaped aperture allows only a limited range of ahead and astern displacement. Alternatively, other shaped apertures may be utilised to restrict the range of movements of the control element 102 as desired.

It will be appreciated that there are various other mechanical, electrical and electronic arrangements which may be utilised to sense the position of the control element 102 relative to the neutral position to thereby generate the X-axis, Y-axis, and Z-axis signals. For example, magnetic, inductive, or optical technologies could be utilised instead of potentiometers or any other means of determining the position of the control element in the X-Y plane and its rotation about the Z-axis, both with respect to the neutral positions, may be used in alternative arrangements of the control device. Further it will be appreciated that other mechanical arrangements may be utilised which enable the control element 102 to be displaced in a plane and to rotate about an axis and the control device need not necessarily include slidable plates and rotatable potentiometers for this purpose.

In response to the X-axis, Y-axis, and Z-axis signals, the control system operates the vessel's propulsion unit(s) and/or any lateral thruster(s) to cause the vessel to surge, sway and/or yaw in accordance with the position of the control element 102. In particular, the vessel rate of movement is determined by the position of the control element 102 relative to the neutral position in the X-Y plane and the Z-axis. For example, if the operator wants the vessel to surge forward, the operator simply moves and holds the control element 102 forward along the X-axis. The further forward it is displaced, the more thrust is produced in that direction by the vessel's propulsion units.

Similarly, to cause a translational movement of the vessel in the transverse direction, the control element 102 is displaced in a sideways direction along the Y-axis. If the operator requires to rotate the vessel, the control element is rotated, clockwise or anticlockwise, in the appropriate direction about the Z-axis, and again, the greater the angle of rotation, the greater the vessel's rate of turn or yaw. Essentially, the control system of the control device 100 will cause the vessel's movement to mimic the displacement of the control element 102.

As the control element 102 has three degrees of freedom, a vast range of vessel manoeuvres are possible which combine the basic surge, sway and yaw movements, via the propulsion and control system of the invention. For example, it is possible to sway the vessel to port while also surging the vessel ahead and/or yawing the vessel clockwise or anticlockwise. To achieve these combination-manoeuvres the control element 102 is simply moved to the desired position within the X-Y plane and/or rotated about its Z-axis. The proportions of each of the fundamental surge, sway and yaw movements which contribute to the final vessel manoeuvre depend on the position of the control element 102 relative to its neutral position in the X-Y plane and the Z- axis. In particular, the further the control element 102 is from its neutral position relative to the X-Y plane and Z-axis, the more thrust is demanded for the respective surge, sway and yaw movements.

The control system may, for example, have a microprocessor, microcontroller, programmable logic controller (PLC) or the like, which is programmed to receive and process the X-axis, Y-axis and Z-axis signals generated via movement of the control element 102. As mentioned, the X-axis and Y-axis signals represent the position of the control element 102 relative to the neutral position in the X-Y plane, while the Z-axis signal represents the angle of rotation of the control element 102 about its Z-axis relative to the neutral position. The control system processes these signals to determine the position and orientation of the control element 102 and therefore the desired manoeuvre required by the operator. Once the control system has determined the type of manoeuvre desired, it generates and sends control signals to the vessel's propulsion unit(s) and/or any lateral thruster(s) to manoeuvre the vessel. The control system can be pre-loaded with data pertaining to the type and number of propulsion unit(s) and lateral thruster(s) (if any) onboard and can be pre-programmed to operate the or each propulsion unit and lateral thraster(s)in combination or alone to manoeuvre the vessel in accordance with the operation of the control element 102. In particular, the control system is programmed to operate the vessel's propulsion systems to cause the vessel to move in a manner which mimics that of the control element 102.

At or towards the limit of movement of the control element in each or any of the X, Y and Z-axes the resistance provided by a spring mechanism, against the pressure of which the operator moves the control element 102, may increase, by use of one or more variable rate spring mechanisms for example, or any other suitable mechanical arrangement. During a first and typically greater part of the range of movement of the control element in any axis, the operator moves the control element against a lesser level of spring pressure and then in a second and typically lesser part of the movement towards the maximum extent of movement of the control element in that axis the bias against which the operator must move the control device increases. At the same time the control system is arranged to cause the rate of thrust increase or rate of movement or turn of the vessel to increase more rapidly during the second part of movement of the control element. Alternatively a force sensor may be provided at or towards the limit of movement of the control element in any axis again at either end of the extent of movement, against which the operator presses to increase the rate of thrust or vessel movement or turn increase at the limit of movement of the control element in the axis.

Figure 6 shows an alternative form of the control device which, along with the control element 102, has an additional manually operable control input in the form of a wheel 200 embedded in the top surface of the control element 102. The wheel 200 may be arranged to control various parameters and settings relating to the way in which the control system operates the vessel's propulsion units during low (or high) speed manoeuvring.

Referring to Figure 7a, the wheel 200 may, for example, be arranged as a gain control for controlling the level of thrust which is demanded in response to movements of the control element 102. In particular, the wheel 200 may be operated to control the relationship between the displacement of the control element 102 from the neutral position, with respect to both movement in the X-Y plane and rotation about the Z-axis, and the level of thrust demanded. In this arrangement, the position of the wheel 200 determines the thrust demand at each control element 102 position with respect to the neutral position and provides the user with a means of setting the upper or maximum speeds attainable during a manoeuvre.

Figure 7a illustrates graphically how the control 200, functioning as a gain control, may control the relationship between the displacement of the control element 102 from the neutral position and the thrust level. By way of example, the thumbwheel may have five positions 201-205 and therefore five different gain settings, position 201 being the lowest gain setting and position 205 being the highest. As the control 200 is rotated from position 201 to 205 the thrust level at any particular control element displacement (apart from at the neutral position) increases, and vice versa as the control is rotated from position 205 to 201. Hence the thrust level at each control element position, and therefore the thrust level during any surge, sway, yaw or combination manoeuvre, will depend on the thumbwheel position.

It will be appreciated that the relationships shown in Figure 7a need not necessarily be linear. Furthermore, the control need only have two distinct positions, but may have many more, or alternatively may operate in a continuous manner without any distinct positions.

In operation, the gain control wheel generates a gain control signal which represents the position of the controlwheel. The control system receives and processes the gain control signal and operates the vessel's propulsion units to generate the desired level of thrust during manoeuvring.

In an alternative arrangement, the wheel 200 may control the sensitivity of the control device and in particular the response time of the vessel to perform a desired manoeuvre as shown in Figure 7b. For example, when the control 200 is positioned for higher sensitivity 205 (fast response time), the control system will operate the vessel's propulsion units to rapidly perform desired vessel manoeuvres in accordance with movements of the control element. Conversely, if the control 200 is positioned for lower sensitivity 201, vessel manoeuvres will be performed more sluggishly. Typically, the response time will depend on the rate of change of thrust and rate of change of steering and therefore these will be controlled in accordance with the wheel sensitivity setting.

Referring to Figure 7b, two possible relationships are shown between the position of the control 200 and the response time. The first relationship 206 is a linear one in which the response time will alter linearly with respect to the wheel position. The second relationship 207 is non-linear and it will be appreciated that any desired linear or nonlinear relationship could be employed by programming or arranging the control system appropriately. As with the gain control arrangement, the sensitivity control 200 generates a sensitivity control signal which is received and processed by the control system to control the response time.

In another alternative arrangement, the wheel 200 may control the engine idle speed(s) of the vessel's propulsion unit(s) according to a linear 208 or non-linear 209 relationship as shown in Figure 7c, wherein the engine idle speed(s) are the speed(s) of the engine(s) of the propulsion unit(s) when the control element 102 is in the neutral position demanding zero thrust.

It will be appreciated that the wheel 200 may be arranged to control other parameters and settings, or any combination thereof. For example, the control 200 may be arranged to control both the gain and engine idle speed. With such an arrangement, the control 200 would control the relationship between the displacement of the control element 102 and the thrust level demanded as described above with reference to Figure 7a, and would also control the engine idle speed as described with reference to Figure 7c. For example, moving the control 200 from position 201 to a higher position (202-205) would increase gain and would also increase the engine idle speed of the propulsion units. There may be multiple controls for different parameters and settings, or a combination thereof. Alternatively, a single multi-purpose control device may be provided which can be switched to control different parameters and settings, or a combination thereof.

The additional control input or inputs for low speed manoeuvring need not necessarily be in the form of a wheel 200 as shown. They may, for example, be push buttons, slide switches, rocker switches, rotary switches, levers, touch pads, dials, or any other type of manually operable input device. For example referring to Figure 1 push buttons 161 and 162 may act as plus and minus controls on gain, sensitivity or engine idle speed, alternative to the control wheel 200 for example. Furthermore, the additional control input or inputs need not necessarily be provided on or in the control element 102 of the control device. They may be located at any other position on the housing 101 of the control device or may be remote from the housing 101 and control element 102 altogether.

The propulsion and control system of the present invention may also be used to manoeuvre vessels at higher speeds, for example when cruising. The control device may have a mode change input device, such as a button or switch, which enables the user to switch the control device between a low speed mode and a cruise mode. When in cruise mode, the control element 102 may be moved forward and backward in the X-axis to control the fore and aft surge of the vessel and may be rotated about the Z-axis to control the yaw or steering of the vessel to port or starboard. Alternatively the system may be supplemented by a separate helm control such as a helm wheel, for use in steering the vessel (Z-axis control) when in cruise mode. Preferably the control device is arranged so that when in cruise mode the control element is not centre-biased along the X-axis and will remain in the forward (or reverse) thrust position to which it is displaced by the operator to maintain under way thrust. For example, the control element may be arranged as a friction device or the like which maintains its position until it is moved by the operator. Sway thrust at higher speeds when cruising would be disabled for safety reasons by locking out movements of the control element in the Y- axis mechanically, although this is not essential. Alternatively, the control element may be free to move in the Y-axis, but the Y-axis signal would be disregarded by the control system when the control device is in cruise mode.

A friction lock device may be provided for all axes of movement of the control element for use in low speed maneourving. Alternatively an electronic position lock may be provided via a press button or other control which may be actuated by the operator to cause the control system to maintain the thrust level and direction of thrust of the propulsion system. In one embodiment the electronic position lock may be released as soon as the operator moves the control element 102 again. For example to hold a vessel against a wharf it may be desired to maintain a constant small level of port or starboard thrust, combined with thrust in another direction depending on the wind direction tending to move the vessel away from the wharf, and this may be achieved by actuating such a device lock which will maintain the current thrust and direction of the propulsion system including any lateral thrusters, until the control element 102 is moved again.

Example 1 -

Propulsion and Control System with Multiple Waterjet Units - Differential Thrust

Capable

Referring to Figure 8, a schematic arrangement of a propulsion and control system of the invention including a control device 100 described above and twin waterjet units 111 is shown. The waterjet units 111 are typically placed port and starboard at the stern of the vessel. Three, four or possibly more units may be controlled together. Each unit is driven by an engine 113 through a driveshaft 114 and has a housing containing a pumping unit 112, steering deflector 115 and reverse duct 116. In this case the reverse ducts are each of a type that feature split passages to improve reverse thrust and affect the steering thrust to port and starboard when the duct is lowered into the jet stream. The steering deflectors pivot about generally vertical axes 117 while the reverse ducts pivot about generally horizontal axes 118 independently of the deflectors. Actuation of the engine throttle, and of the steering deflector and reverse duct of each unit is caused by actuation signals received through control input ports 119, 120, 121 respectively. For clarity, the control device 100 is shown as the only manual control device for the vessel, although it will be appreciated that in practice it may supplement other steering and thrust control system arrangements which utilise a joystick, a helm control, and throttle lever(s) for higher speed or all speed control.

As mentioned, X-axis, Y-axis, and Z-axis signals 122 are generated in response to the movement of the control element 102 by an operator. The signals 122 are received by a control system 123, and are processed and sent 124 to actuator modules 125 to operate the waterjet units and engine throttles to manoeuvre the vessel. In particular, the actuator modules 125 generate actuation signals 126 which are input through ports 119, 120, 121 to control the engine throttle, and steering deflector and reverse duct of each waterjet unit. While the control device 100 is shown as hardwired to the actuator modules 125, alternatively the control device 100 may, for example, be a remote unit which communicates with the vessel's control system and/or actuator modules via a wireless link.

Figure 9 shows six basic low speed manoeuvres of a vessel which may be enabled by the propulsion and control system of the invention. These include four translations 1,2,5,6 in which the vessel moves ahead, astern, to port or to starboard respectively, while maintaining a constant compass heading. Figure 9 also shows two rotations 3,4 in which the vessel turns to port or starboard about a center point in the vessel respectively. Manoeuvres resulting from the operation of the control element 102 in each case are shown. The steering deflectors are operated in synchronism while the reverse ducts are operated in synchronism or differentially as summarised in Table 1 below. Virtually any movement of the vessel may be achieved by a combination of these basic manoeuvres. The propulsion and control system allows an operator to use the control element 102 in a simple intuitive fashion to cause movement of the vessel i.e. the vessel's movement mimics that of the control element 102.

Displacing the control element 102 ahead or astern synchronises the reverse ducts and throttle demands and the effect is the same as operating a vessel with a single waterjet in manoeuvres 1,2. While located at its neutral position in the X-Y plane, rotating the control element 102 clockwise or anticlockwise in manoeuvres 3,4 causes a partial lowering of the reverse ducts and full movement of the steering deflectors to rotate the vessel about its center in a corresponding direction. Displacing the control element 102 transversely causes the vessel to translate sideways in manoeuvres 5,6 via a combination of differential thrust and steering. In particular, the port and starboard waterjets produce differential thrust (i.e. one waterjet unit produces ahead thrust with the reverse duct raised while the other produces astern thrust with the reverse duct lowered) which causes the vessel to rotate about the stern. However, the steering deflectors of the waterjet units are also positioned to counteract this rotation, resulting in a sideways translation of the vessel. The control system may automatically apply a preset movement of the steering nozzles ("steering offset") on movement of the control element 102 from the neutral position in the Y-axis. Alternatively the degree of steering offset applied may be varied by the control system to be proportional to the thrust level simultaneously commanded by the operator. Alternatively again an autopilot system associated with the control system may operate in conjunction with the control system to maintain a constant commanded heading (direction of the bow of the vessel) during the sideways translation - that is, when the operator moves the control element 102 to port or starboard in the Y-axis to command a port or starboard sideways translation of the vessel, the position of the steering nozzles may be controlled by the control system but based on heading information provided by an autopilot system, so that the steering nozzles are initially positioned and adjusted as necessary during the translation movement, to maintain a constant heading, or a commanded heading, for the vessel. Alternatively again a rate sensor arranged to generate a turn rate signal indicative of vessel turn rate may be provided and the control system may be configured to monitor for any turn via the turn rate sensor at the bow of the vessel, and to adjust the position or angle of the steering nozzles to compensate so as to maintain a constant heading during a sideways translation; the control system may be configured to receive a vessel actual turn rate signal from the turn rate sensor and a desired turn rate signal and to compare the two and to control the steering nozzles to minimise a difference between the signals, and maintain or initiate a desired turn rate where the control device is manipulated by the operator to cause the vessel to also turn during a sideways translation of the vessel; the turn rate sensor may be a yaw rate sensor for example a rate gyro fixed to the vessel to sense yaw motions of the vessel. Any of these functionalities for providing steering offset via the control system during a sideways translation may be provided to the systems described in the subsequent examples 2-4.

Figure 10 schematically shows a vessel 127 with a twin waterjet arrangement and control device 100. A sideways manoeuvre to port is in progress, such as manoeuvre 5 indicated in Figure 9. Nozzles 128, steering deflectors 129 and one of the reverse ducts 130 are shown at the stern of the vessel to indicate the port and starboard waterjets. The reverse duct on the starboard waterjet is not positioned to deflect the water flow from that jet and has been omitted from view. The control element 102 of the control device 100 has been pushed to port by the operator. This produces jet streams 131 from the waterjets and consequently thrust vectors 132. The net sideways force acts at a point 133 towards the center of the vessel represented by thrust vector 134.

It will be appreciated that the control device may be provided with one or more additional manually operable control inputs in the form of a thumbwheel 200 or other input device as discussed above to control gain, sensitivity, engine idle speed, or any combination thereof and that the control system may be arranged to operate the waterjet units 111 and/or engines 113 in accordance with the operation of the additional control input(s). The control device may also be operated to manoeuvre the twin waterjet vessel at higher speeds when cruising. As mentioned above, the control device may have a mode change button or the like for switching between a low speed mode and a cruise mode. Operation of the control device in the low speed mode has been described above with reference to Figure 9 and Table 1. When in cruise mode, the control system 123 (Figure 8) disregards the Y-axis signal which represents sway demand (transverse translational movements) and therefore does not operate the waterjet units 111 to produce differential thrust. The control element 102 only controls the surge of the vessel and the yaw or steering of the vessel. In particular, the control system 123 operates the engine throttles 113 and reverse ducts 116 of the waterjet units 111 in a synchronise manner in accordance with movements of the control element 102 in the X-axis to surge the vessel fore and aft as desired, and operates the steering deflectors 115 in accordance with rotation of the control element 102 about the Z-axis to yaw or steer the vessel to port or starboard as desired. It will be appreciated that in cruise mode, the control element 102 may alternatively be mechanically constrained with respect to movement in the Y-axis to disable sway thrust at higher speeds. As mentioned, the control element 102 may, when in cruise mode, be arranged as a friction device or the like so that it maintains its position until it is moved by an operator i.e. it is not center-biased.

Example 2 -

Propulsion and Control System with Multiple Waterjet Units and Lateral Thruster(s) - Differential Thrust Capable

Figure 11 shows a variant of the schematic arrangement described with reference to Figures 8-10 in which the control device 100 also controls a lateral thruster, such as a bow thruster 136, to supplement the thrust forces provided by the twin waterjet units 111 during various vessel manoeuvres, such as sideways translations and vessel rotations, undertaken at low speeds.

The bow thruster 136 is located at the bow 135 of the vessel and is operable to produce lateral thrust forces to either port or starboard as indicated by thrust vectors 137,138 respectively. The bow thruster 136 has, for example, an impeller driven by a reversible motor. The reversible motor is operated by an actuator module 139 which sends actuation signals 140 to control the speed and direction of the reversible motor and thereby the direction and magnitude of the lateral thrust produced by the bow thruster 136.

In operation, the control device 100 controls the waterjet units 111 and engines 113 in the same manner as described above in relation to example 1. In addition, the control device 100 controls the bow thruster 136 for particular vessel manoeuvres. In particular, the control device 100 sends a control signal 141 to actuator module 139 which in turn operates the bow thruster 136 via actuation signal 140 for vessel manoeuvres such as vessel rotation and sideways translations.

By way of example, Figure 12 shows how the bow thruster 136 may supplement the six basic low speed manoeuvres shown in example 1. As indicated in Figure 12, the bow thruster provides additional lateral forces on the bow of the vessel to assist rotational movements 3,4 (clockwise or anticlockwise) and sideways translations 5,6 (port or starboard) of the vessel. Table 2 below summarises the status of the steering deflectors and reverse ducts for the waterjet units 111 and the status of the bow thruster 136 for each of the six basic low speed manoeuvres. As indicated in Table 2, the steering deflectors are operated in synchronism, while the reverse ducts are operated in synchronism or differentially.

Example 3 -

Propulsion and Control System with Multiple Water jet Units and Lateral Thruster(s) - Not Differential Thrust Capable

As described in example 2 with reference to Figures 11 and 12, the control device 100 can be arranged to operate a vessel driven by multiple waterjet units (having differential thrust capability) and a bow thruster to perform various low speed manoeuvres. However, the control device 100 can also be arranged to control such a vessel without utilising differential thrust for manoeuvres such as sideways translations to port or starboard and rotation about the center of the vessel. This flexibility allows the control device to operate on a vessel in which the steering deflectors and reverse ducts of the waterjet units are only moveable in unison.

In this situation, the schematic arrangement is the same as that shown in Figure 11, but the control device 100 implements sideways translational movements in a different manner without the assistance of differential thrust. As shown in Figure 13, the surge translational movements 1,2 (ahead or astern) are the same as that shown in Figure 12.

The rotational movements 3,4 (clockwise or anticlockwise) are also substantially the same, except there the thrust applied by each waterjet unit is identical as the reverse ducts move in unison. The sideways translational movements 5,6 are different and are implemented via a combination of port or starboard thrust at the stern of the vessel produced by the waterjet units and corresponding port or starboard thrust at the bow of the vessel produced by the bow thruster. Table 3 below summarises the status of the steering deflectors and reverse ducts for the waterjet units and the status of the bow thruster for each of the six basic low speed manoeuvres referred to previously. As indicated in Table 3, the steering deflectors and reverse ducts of the waterjet units are operated in unison for each basic manoeuvre.

Example 4 - Propulsion and Control System with Single Waterjet Unit and Lateral Thruster(s)

Referring to Figure 14, a schematic arrangement of a propulsion and control system of the invention comprising a single waterjet unit 111 is shown. The waterjet unit 111 is typically placed in the center at the stern of the vessel and has the same assembly and componentry as was described in respect of the waterjet units in Figure 8. In the bow 135 of the vessel is a bow thruster 136 which is operable to produce lateral thrust forces to either port or starboard as indicated by thrust vectors 137,138 respectively.

The bow thruster 136 has, for example, an impeller driven by a reversible motor. The reversible motor is operated by an actuator module 139 which sends actuation signals 140 to control the speed and direction of the reversible motor and thereby the direction and magnitude of the lateral thrust produced by the bow thruster 136.

In operation, the control device 100 controls the waterjet unit 111, engine 113, and bow thruster 136 via their respective actuation modules 125,139 to manoeuvre the vessel during, for example, low speed operations such as docking and setting off in a marina or the like. In particular, X-axis, Y-axis, and Z-axis signals 122 are generated in response to the displacement of the control element 102 of the control device 100 by an operator. The signals 122 are received by a control system 123, and are processed and sent 124,141 to actuator modules 125,139 to operate the waterjet unit 111, engine 113, and bow thruster 136 to manoeuvre the vessel. As mentioned, the actuator module 125 generates actuation signals 126 which are input through ports 119, 120, 121 to control the engine throttle, and steering deflector and reverse duct of the waterjet unit 111, while actuator module 139 generates actuation signals 140 to control the speed and direction of the reversible motor of the bow thruster 136.

Figure 15 shows the same six basic low speed manoeuvres shown previously, except for a single waterjet vessel with a bow thruster as illustrated in Figure 14. As with the twin waterjet vessel embodiments of examples 1-3, the basic manoeuvres are enabled by the control device 100 and include four translations 1,2,5,6 in which the vessel moves ahead, astern, to port or to starboard respectively, while maintaining a constant compass heading. Figure 15 also shows two rotations 3,4 in which the vessel turns to port or starboard about a center point in the vessel respectively and manoeuvres resulting from the operation of the control element 102 in each case are shown.

The waterjet unit 111 and bow thruster 136 are operated as summarised in Table 4 below for the six basic manoeuvres. Virtually any movement of the vessel may be achieved by a combination of these basic manoeuvres. As shown in Figure 15, the control system operates the waterjet unit 111 and bow thruster 136 to cause the vessel to move in such a way that mimics the movement of the control element 102.

Like the twin waterjet vessel embodiments described above, the control device may be equipped with one or more additional manually operable control inputs for controlling gain, sensitivity, engine idle speeds, or any combination thereof. The additional control inputs may be in the form of a thumbwheel or alternatively any other manually operable input device may be utilised, examples of which have been given.

The control device may also be operated to manoeuvre the single waterjet vessel with bow thruster at higher speeds when cruising by changing the control device from a low speed mode to cruise mode via operation of a button, switch or the like. Operation of the control device in the low speed mode has been described above with reference to Figure 15 and Table 4. When in cruise mode, the control system 123 (Figure 14) disregards the Y-axis signal which represents sway demand (transverse translational movements) and therefore completely disables the bow thruster to prevent lateral thrust being produced at higher speeds. The control element 102 only controls the surge of the vessel and the yaw or steering of the vessel. In particular, the control system 123 operates the engine throttle 113 and reverse ducts 116 of the waterjet unit 111 in accordance with movements of the control element 102 in the X-axis to surge the vessel fore or aft as desired, and operates the steering deflector 115 in accordance with rotation of the control element 102 about the Z-axis to yaw or steer the vessel to port or starboard as desired. It will be appreciated that in cruise mode, the control element 102 may alternatively be mechanically constrained with respect to movement in the Y-axis to disable operation of the bow thruster at higher speeds. Further, the control element 102 may, when in cruise mode, be arranged as a friction device or the like so that it maintains its position until it is moved by an operator i.e. it is not center-biased.

It will be appreciated that the vessels described in examples 2-4 could additionally utilise one or more other lateral thrusters to assist the bow thruster and that all the lateral thrusters may be controlled by the control device according to the particular manoeuvre desired. For example, the vessels may have one or more bow thrusters and one or more stern thrusters that assist the waterjet unit(s) to manoeuvre the vessel as desired by the operator as they operate the control element 102 of the control device 100. It will be appreciated that the control device of the invention can be implemented in a wide range of forms on a wide range of marine vessels. For example, the control device can be adapted to suit vessels which are propelled by one or more waterjet units, inboard or outboard motors, stern drives and those which have one or more bow and stern thrusters, whether orientated laterally or otherwise. Details of the vessels, the individual control components and the propulsion units will be well known to a skilled reader.

Advantages

A particular benefit of the propulsion and control system of the invention comprising a manually movable control element rotatable about an axis and movable in a plane and waterjet unit(s) optionally supplemented by one or more lateral thrusters, is that when reversing a vessel or going astern, whether directly a stern or astern and to port or starboard, control of the vessel remains via movement of the control element in the direction of vessel movement desired and remains highly intuitive. With a propeller driven vessel using a rudder for steering, when the vessel is moving in the ahead direction port and starboard movements of the steering control cause port and starboard movements of the vessel. When the vessel is moving in the astern direction, port and starboard movements of the steering control cause the opposite movement of the bow of the vessel, that is, moving the steering control to port results in the bow of the vessel moving to starboard. This steering sense is the same as that of a motor vehicle. On vessels driven by waterjets with split duct reverse defelctors, when moving in the ahead direction the steering sense is the same as that for a propeller driven vessel. However when moving astern the steering sense is the same as when moving ahead, that is, opposite to a propeller vessel. With the propulsion and control system described, where steering control is applied via a boat shaped device moving horizontally about a vertical Z-axis, steering control in both ahead and astern directions are immediately intuitive as the movement of the control device translates directly to the resultant movement of the vessel, whether moving ahead or astern. The degree to which this is intuitive and thus easy for an operator to use or a new operator to adapt to is substantially more than in a system in which a 3-axis joystick control device is used.

Claims

1. A propulsion and control system for a marine vessel comprising: two or more waterjet units for propelling the vessel; a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane; and an associated control system arranged to operate the waterjet units to manoeuvre the vessel in accordance with movement of the control element.

2. A propulsion and control system for a marine vessel comprising: one or more waterjet units and one or more lateral thrusters; a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane; and an associated control system arranged to operate the waterjet unit(s) and lateral thruster(s) to manoeuvre the vessel in accordance with the movement of the control element.

3. A propulsion and control system according to either one of claims 1 and 2 wherein the marine vessel is propelled by one or more waterjet units and has at least one lateral bow thruster.

4. A propulsion and control system according to any one of claims 1 to 3 arranged to operate the waterjet unit(s) or the waterjet unit(s) and lateral thruster(s) so that displacement of the control element in the plane will cause a corresponding rate of movement for the vessel in the direction in which the control element is moved, and rotation of the control element, either clockwise or anticlockwise, will cause yaw of the vessel about a vertical axis.

5. A propulsion and control system according to any one of claims 1 to 4 wherein the control system is arranged to generate signals which actuate steering deflector(s) and reverse duct(s) of the waterjet unit(s) and throttle(s) of the engine(s) which drive the waterjet unit(s)..

6. A propulsion and control system according to any one of claims 1 to 5 wherein the control element in at least one mode is biased toward a neutral position with respect to both movement in the plane and rotation and the control system is arranged to operate the waterjet unit(s) at zero thrust when the control element is in said neutral position.

7. A propulsion and control system according to any one of claims 1 and 2 and 4 to 6 when dependent thereon wherein the control system is arranged to actuate steering deflectors of the multiple waterjet units in synchronism, and reverse ducts of the waterjet units in synchronism and differentially.

8. A propulsion and control system according to claim 7 wherein the control system is arranged to actuate the reverse ducts of the waterjet units differentially on movement of the control element laterally.

9. A propulsion and control system according to claim 8 wherein the control system is arranged to cause predetermined movement of one or more steering deflector(s) of the propulsion system on movement of the control element to cause sideways translation of the vessel.

10. A propulsion and control system according to claim 3 and any one of claims 4 to 6 when dependent on claim 3 comprising a single waterjet unit.

11. A propulsion and control system according to any one of claims 1 to 10 wherein the control system is arranged such that increasing displacement of the control element from a neutral position increases thrust for translational movements of the vessel and an increasing angle of rotation of the control element from a neutral position increases the rate of yaw of the vessel.

12. A propulsion and control system according to any one of claims 1 to 11 wherein the control element is marine vessel-shaped.

13. A propulsion and control system according to any one of claims 1 to 12 wherein the control element is rotatable about an axis which is substantially perpendicular to said plane.

14. A propulsion and control system according to any one of claims 1 to 13 wherein the control device is arranged such that the movement of the control element is restricted to a limited area.

15. A propulsion and control system according to any one of claims 1 to 14 wherein the control device further comprises an additional manually operable control input device for changing the relationship between movement of the control element and the thrust response from the waterjet(s).

16. A propulsion and control system according to claim 15 wherein the additional control input device is carried by the control element.

17. A propulsion and control system according to claim 16 wherein the additional control input device comprises a rotary control device.

18. A propulsion and control system according to any one of claims 15 to 17 wherein said additional control input device is arranged to control the relationship between the displacement of the control element from a neutral position and the level of thrust from the propulsion unit(s).

19. A propulsion and control system according to any one of claims 15 to 17 wherein said additional control input device is arranged as a sensitivity control for movement of the control element.

20. A propulsion and control system according to any one of claims 15 to 17 wherein said additional control input device is arranged to control an idle speed of the propulsion unit(s).

21. A propulsion and control system according to any one of claims 1 to 20 including an autopilot system operable to in conjunction with the control system cause the vessel to maintain a commanded heading during sideways translation of the vessel.

22. A propulsion and control system according to any one of claims 1 to 20 wherein the control system is operable to monitor via a turn rate sensor for turn at the bow of the vessel and to cause the vessel to maintain a commanded heading during sideways translation of the vessel.

23. A propulsion and control system according to any one of claims 1 to 20 including a mechanical or electronic current thrust and direction lock system operable to cause the propulsion and control system to maintain a current level and direction of thrust until released.

24. A propulsion and control system according to claim 23 configured so that movement of the control element after engagement of said current thrust and direction lock system will release the lock system.

25. A propulsion and control system according to any one of claims 1 to 24 wherein the control device and system is switchable between a low speed mode for controlling low speed manoeuvres and a cruise mode for controlling vessel manoeuvres at higher speeds.

26. A propulsion and control system for a marine vessel comprising: two or more waterjet units for propelling the vessel: a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane over a reference surface below the control element; and an associated control system which operates the waterjet units to manoeuvre the vessel in accordance with the movement of the control element.

27. A propulsion and control system for a marine vessel comprising: one or more waterjet units and one or more lateral thrusters comprising: a control device including a manually moveable control element which is rotatable about an axis and moveable in a plane over a reference surface below the control element; and an associated control system which operates the waterjet unit(s) and lateral thruster(s) to manoeuvre the vessel in accordance with the movement of the control element..

28. A control device according to claims 27 comprising a single waterjet unit and wherein said lateral thruster is a bow thruster.

29. A propulsion and control system according to either one of claims 26 and 27 arranged to operate the waterjet unit(s) or the waterjet unit(s) and lateral thruster(s) so that displacement of the control element in the plane will cause a corresponding rate of movement for the vessel in the direction in which the control element is moved, and rotation of the control element, either clockwise or anticlockwise, will cause yaw of the vessel about a vertical axis.

30. A propulsion and control system according to any one of claims 26 to 29 wherein the control system is arranged to generate signals which actuate steering deflector(s) and reverse duct(s) of the waterjet unit(s), and throttle(s) of engine(s) which drive the waterjet unit(s).

31. A propulsion and control system according to any one of claims 26 and 30 wherein the control element in at least one mode is biased toward a neutral position with respect to both movement in the plane and rotation and the control system is arranged to operate the waterjet unit(s) at zero thrust when the control element is in said neutral position.

32. A propulsion and control system according to any one of claims 26 to 31 wherein the control element in at least one mode is biased toward a neutral position with respect to both movement in the plane and rotation and the control system is arranged to operate the waterjet unit(s) at zero thrust when the control element is in said neutral position.

33. A propulsion and control system according to claim 32 wherein the control system is arranged to actuate the reverse ducts of the waterjet units differentially on movement of the control element laterally.

34. A propulsion and control system according to any one of claims 26 to 33 wherein the control system is arranged to cause predetermined movement of one or more steering deflector(s) of the propulsion system on movement of the control element to cause sideways translation of the vessel.

35. A propulsion and control system according to claim 28 and any one of claims 29 to 31 when dependent on claim 29 comprising a single waterjet unit.

36. A propulsion and control system according to any one of claims 26 to 34 wherein the control system is arranged such that increasing displacement of the control element from a neutral position increases thrust for translational movements of the vessel and an increasing angle of rotation from the neutral position increases the rate of yaw of the vessel.

37. A propulsion and control system according to any one of claims 26 to 36 wherein the control element is marine vessel-shaped.

38. A propulsion and control system according to any one of claims 26 to 37 wherein the control element is rotatable about an axis which is substantially perpendicular to said plane.

39. A propulsion and control system according to any one of claims 26 to 38 wherein the control device is arranged such that the movement of the control element is restricted to a defined area.

40. A propulsion and control system according to any one of claims 26 to 39 wherein the control device further comprises one or more additional manually operable control inputs for changing the relationship between movement of the control element and the thrust response from the waterjet(s).

41. A propulsion and control system according to claim 40wherein the additional control input device is carried by the control element.

42. A propulsion and control system according to claim 41 wherein the additional control input device comprises a rotary control device.

43. A propulsion and control system according to either one of claims 40 and 42 wherein said additional control input device is arranged to control the relationship between the displacement of the control element from a neutral position and the level of thrust from the propulsion unit(s).

44. A propulsion and control system according to either one of claims 40 and 42 wherein said additional control input device is arranged as a sensitivity control for movement of the control element.

45. A propulsion and control system according to either one of claims 40 and 42 wherein said additional control input device is arranged to control an idle speed of the propulsion units.

46. A propulsion and control system according to any one of claims 26 to 45 including an autopilot system operable to in conjunction with the control system cause the vessel to maintain a commanded heading during sideways translation of the vessel.

47. A propulsion and control system according to any one of claims 26 to 45 wherein the control system is operable to monitor via a turn rate sensor for turn at the bow of the vessel and to cause the vessel to maintain a commanded heading during sideways translation of the vessel.

48. A propulsion and control system according to any one of claims 26 to 45 including a mechanical or electronic current thrust and direction lock system operable to cause the propulsion and control system to maintain a current level and direction of thrust until released.

49. A propulsion and control system according to claim 48 configured so that movement of the control element after engagement of said current thrust and direction lock system will release the lock system.

50. A propulsion and control system according to any one of claims 26 to 49 wherein the control device and system is switchable between a low speed mode for controlling low speed manoeuvres and a cruise mode for controlling vessel manoeuvres at higher speeds.