GB1561281A - Co-ordinated control of a ships twin rudders - Google Patents

Description

(54) CO-ORDINATED CONTROL OF A SHIP'S TWIN RUDDERS (71) I, VINCENT PETER BINGHAM of British nationality of The Spinney, Magpie Lane, Coleshill, Buckinghamshire, do hereby declare the invention, for which I pray that a patent may be granted to me and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a method and apparatus for co-ordinated control of a ship's twin rudders.

The invention has particular though not exclusive application to control of twin rudders for ships of the kind described in Patent Specification No. 1519243 Werftunion GmbH and Co.

Such twin rudders are required to be movable from a basic configuration in which the two rudders are generally parallel, to configurations in which they are both to port or both to starboard or the port one is to port and the starboard one is to starboard, by the same or differing angles. The basic configuration and eight other primary configurations which may be desired are illustrated in Figures 1 to 9 of the accompanying drawings. The notation adopted hereinafter is that movement of the port rudder from the basic position clockwise when viewed from above is movement through a positive angle and anti-clockwise is move ment through a negative angle and movement of the starboard rudder anti-clockwise is movement through a positive angle and clockwise is movement through a negative angle.

According to one aspect of the invention there is provided a method of controlling, in a co-ordinated manner, a ship's twin rudders comprising displacing from a neutral position, one end of a joystick pivoted on a ball-mounting intermediate its ends and having its other end coupled to two members pivoted on axes which are mutually perpendicular and each disposed at 45 to the longitudinal axis of the ship with the members coupled to a respective servo system coupled to a respective one of the twin rudders, thereby to move the rudders to produce a movement of at least the stern of the ship in the direction in which said one end of the joystick was moved from the neutral position.

According to another aspect of the invention apparatus installed or to be installed in a ship with twin rudders for effecting co-ordinated control of the ship's twin rudders comprises a joystick pivoted intermediate its ends on a ball mounting, having one end free for manual engagement and movement thereby and having its other end engaged in a respective slot in each of two arcuate members pivoted on mutually perpendicular axes each of which is disposed at 45 to the longitudinal axis of the ship, said members each being coupled to a respective servo system coupled to a respective one of the twin rudders such that movement of said one end of the joystick causes said other end of the joystick to move along the slot in at least one of said members and to pivot at least the other of said members about its pivot axis to cause the respective servo system to adjust the angle of the respective one of the twin rudders to produce a movement of at least the stern of the ship in the direction in which said one end of the joystick was moved.

Movement of the joystick except along one or other of the axes disposed at 45 to the longitudinal axis of the ship will cause both of said members to move about such axes and therefore, via the servo systems, movement of both of the twin rudders.

Preferably a gate is provided for the joystick to limit the extent of movement thereof, such gate preferably having the shape of an angular figure eight.

Preferably the servo systems include potentiometers from which a positive or negative voltage is tapped and the servo systems also include servo motors effective to move the rudders to an angular position corresponding to the voltage tapping of the potentiometer at any instance.

Alternatively however the servo systems could be substantially non-electric i.e. they could operate hydraulically or pneumatically via valves controlled by the position of the respective one of the members moved by movement of the joystick.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, m which Figures 1 to 9 show primary positions to which twin rudders of the ship may be required to be moved by the method and apparatus according to the invention and include an indication of the joystick position to obtain that position, Figure 1 being drawn to a larger scale than Figures 2 to 9; Figure 10 is a perspective view of a joystick controller of apparatus according to the invention; and Figure 11 is a schematic diagram indicating a gated movement of the joystick controller of Figure 10 in conjunction with control potentiometers.

Referring to the drawings and firstly to Figure 1, a ship, the hull of which is generally indicated at 1, has a propeller 2 and twin rudders 3 and 4 pivoted about respective axes 5 and 6. In the position shown in Figure 1 where the rudders are not deflected through an angle, the inner faces 7 and 8 of the rudders 3 and 4 respectively are substantially parallel to the longitudinal axis of the ship and the outer faces 9 and 10 respectively of the rudders 3 and 4 are at their front faces convex because of a bulbous nose portion for each rudder, and the rear portion is concave so that at the tail end the outer face 9 and 10 of each rudder is flaring outwardly. Further primary positions of the rudders 3 and 4 for steering the ship are shown in Figures 2 to 9, in each case the resultant movement of the ship being indicated by an arrow.

For normal course navigation, the rudders are moved substantially in parallel.To run a turning manoeuvre, the 55 and 75 rudder angles are steered as well. By oppositely moving the two rudders to 105 outboard, the propeller slip stream is reflected obliquely forward partly because of two bent-off end plates (not shown) located at top and bottom of the rudders. The rudders are then acting like a Pelton wheel blade and produce an astern thrust of about 40% of the bollard pull. The opposite rudder movement provides corresponding possibilities of use.

When the ship is making headway, oppositely laying the rudders to 105 outboard, Figure 7, with the propeller continuing to turn ahead enables the stopping distance to be considerably reduced as compared with that achieved with the propeller turning astern. The rudders are then acting like a braking parachute the effect of which is still increased by the propeller slip stream. The higher the ship's speed and engine output, the much bigger is the braking power.

In addition, the braking distance is further shortened by saving the time of engine reversal.

During a stopping procedure, the ship remains fully steerable by only slightly moving the two rudders positioned outboard.

With the propeller rotating ahead, the ship is capable of proceeding astern, whereby again an unobjectionable steerability exists in response to slight rudder movements, Figures 8 and 9, and of running extremely narrow astern turning circles having a turning circle diameter equal to nearly a ship's length. The astern power produceable by the rudders with the propeller rotating full ahead can be close to 40% of the bollard pull and meets the usual requirements for sea-going ships so that engine reversal or an astern turbine may possibly be dispensed with.

With a constantly rotating propeller, the separately steered rudders enable a progressive transition from full ahead to full astern by changing the rudder angle. When doing this, there is an intermediate position at which neither an astern thrust nor an ahead thrust occurs with the propeller rotating ahead, Figure 4. It can also be directly proceeded from the ahead, astern or neutral position to port or starboard by slight rudder movements without having to stop or reverse the engine in between. The engine speed i.e. the maximum power available, can be matched to the requirements imposed by the interference effects of wind and current so that no unnecessary energy consumption takes place. Only one sense of engine rotation is required.

Each of the primary positions of Figures 1 to 9 is indicated by reference letters and the following table shows the angles of the port rudder 3 and starboard rudder 4 for each primary position together with the resulting movement of the ship.

Reference Letter Port Rudder Starboard Rudder Movement of Ship A - 55 75 Head to starboard B 0o o Ahead C 75 - 55 Headtoport D 60 60 Station keeping E 45 85 Stern to starboard F 85 45 Stern to port G 75 105 Astern to starboard H 105 105 Astern J 105 75 Astern to port The angles given are only approximate angles and actual angles used may vary widely from those given according to the particular shape and disposition of the rudders, the design of the ship and the purpose for which it is designed.

Figure 10 shows a joystick controller for controlling the movements of the rudders 3 and 4 to the various angles shown in the table. The joystick controller comprises a body member 11 in which a joystick 12, having a knob 13 at its upper end, is mounted on a ball joint 14 so that it is freely movable and has a portion 12a projecting below the body portion 11. Two arcuate members 15 and 16 are pivotally mounted at each of their ends on the body member 11 each about a respective axis 17, 18, the axes 17 and 18 being mutually perpendicular and the body member 11 being so mounted on the ship that each axis 17,18 extends substantially at 45 to the longitudinal axis of the ship.

The members 15,16 have respective slots 19,20 inwhich the lowerprojectingportion 12a of the joystick 12 is engaged and the members 15, 16 each mount a respective wiper 21, 22 bearing on a respective potentiometer coil or connected to tappings thereof. It will be seen that movement of the knob 13 merely in a vertical plane which includes the axis 17 will not cause the portion 12a to pivot the member 15, the portion 12a merely moving in the slot 19 thereof, but will pivot the member 16.In like manner, movements of the control knob 13 in a vertical plane including the axis 18 will not cause any movement of the member 16, the portion 12a merely moving in the slot 20 thereof, but will pivot the member 15 about the axis 17. Movement of the control knob 13 in any other direction than in the two vertical planes detailed above will cause pivoting movement of both the member 15 and the member 16 and a consequent adjustment of each of the respective potentiome.ers.

The potentiometers are shown in Figure 11 and comprise a starboard rudder potentiometer 23 and a port rudder potentiometer 24. Each potentiometer 23, 24 has a 0 tapping, a negative portion up to 55 and posiLive portion up to 105 . The potentiometers extend perpendicular to one another and each extend at 45 to the longitudinal axis of the ship.A gate, not shown, is provided for the portion 12a of the joystick 12 to constrain it for movement within an angular figure eight shape defined by the lines D A B C D F J H G E D, the reference letters used in Figure 11 corresponding to the reference letters used in Figure 1 to 9 and the position to which the knov 13 of the joystick 12 must be moved to obtain the particular setting of the rudder as shown in each of Figures 1 to 9. Thus, for example moving the joystick 12 to the position A of Figures 3 will obtain a -55 setting of the port rudder, a 75 setting of the starboard rudder and a turn to port of the ship.

The controller 13 can also be moved so that any position within the angular figure eight gated portion referred to above can be adopted. The potentiometers 23, 24 can be linear or non-linear but are preferably non-linear. Suitable joystick controllers and potentiometers are those sold by Penny & Giles Potenti nmeters Limited of Christchurch Hampshire under references JS2 and HDC2 but proved d with an additional gate of an angular figure eight shape.

The angular movement of the rudders effected by servo means controlled by the voltages tapped from the potentiometers can be directly proportional to the change in potential of the associated control potentiomete. 23 or 24. However to obtain appropriate movement of the joystick 12 in both ahead and astern manoeuvring it is desirable to make the potentiometers non-linear in performance. This could be done in various ways but a suitable one is to make the scale of the potentiometer lengths KA and KC shown in Figure 11 one quarter of the scale of the potentiometer lengths AL and CM respectively. Figure 11 shows this non-linearity.

Movement of the joystick within the area D F J H G E D will cause the stern of the ship to remain stationary or to move astern at any speed and in any direction desired by a natural and logical movement of the joystick 12 in distance and direction. Similar controlled movement of the ship going ahead will be achieved by movement of the joystick within the area A B C D A. The gate to limit the movement of the joystick 12 may if desired be made up of smooth curves closely surrounding the two areas referred to above, but when the ship is moving ahead, positioning the joystick 12 along the lines BA and BC will give the most effective steering control with the least rudder drag.

Instead of using electrical potentiometers, hydraulic or pneumatic valves may be coupled to the arcuate members 15 and 16 to control hydraulic or pneumatic servo means coupled to the rudders directly.

WHAT I CLAIM IS: 1. A method of controlling, in a co-ordinated manner, a ship's twin rudders comprising displacing from a neutral position one end of a joystick pivoted on a ball mounting intermediate its ends and having its other end coupled to members pivoted on axes which are mutually perpendicular each disposed at 450 to the longitudinal axis of the ship with the members coupled to a respective servo system coupled to a respective one of the twin rudders, thereby to move the rudders to produce a movement of at least the stern of the shv in the direction in which said one end of the joystick was moved from the neutral position.

2. Apparatus installed or to be installed in a ship with twin rudders for effecting coordinated control of the ship's twin rudders comprising a joystick pivoted intermediate its ends on a ball mounting, having one end free for manual engagement and movement thereby and having its other end engaged in a respective slot in each of two arcuate members pivoted on mutually perpendicular axes each of which is disposed at 450 to the longitudinal axis of the ship, said members each being coupled to a respective servo system coupled to a respective one of the twin rudders such that movement of said one end of the joystick causes said other end of the joystick to move along the slot in at least one of said members and to pivot at least the other of said members about its pivot axis to cause the respective servo system to adjust the angle of the respective one of the twin rudders to produce a movement of at least the stern of the ship in the direction in which said one end of the joystick was moved.

3. Apparatus according to claim 2, including a pair of potentiometers, each coupled to a respective one of said members such that the voltage tapping on the potentiometers is adjusted. by movement of the respective one of said members, said potentiometers being coupled to said servo systems.

4. Apparatus according to claim 2, including hydraulic or pneumatic valves coupled to said members and opened or closed by movement of said members, said valves being connected to pneumatic or hydraulic servo means coupled to said rudders.

5. Apparatus according to any one of claims 2 to 4, including a gate to restrict movement of said joystick to within an area having approximately the shape of an angular figure eight.

6. A method of controlling, in a co-ordinated manner, a ship's twin rudders as claimed in claim 1 and substantially as hereinbefore described.

7. Apparatus installed or to be installed in a ship with twin rudders for effecting coordinated control of the ship's twin rudders substantially as hereinbefore described and illustrated with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. the scale of the potentiometer lengths KA and KC shown in Figure 11 one quarter of the scale of the potentiometer lengths AL and CM respectively. Figure 11 shows this non-linearity. Movement of the joystick within the area D F J H G E D will cause the stern of the ship to remain stationary or to move astern at any speed and in any direction desired by a natural and logical movement of the joystick 12 in distance and direction. Similar controlled movement of the ship going ahead will be achieved by movement of the joystick within the area A B C D A. The gate to limit the movement of the joystick 12 may if desired be made up of smooth curves closely surrounding the two areas referred to above, but when the ship is moving ahead, positioning the joystick 12 along the lines BA and BC will give the most effective steering control with the least rudder drag. Instead of using electrical potentiometers, hydraulic or pneumatic valves may be coupled to the arcuate members 15 and 16 to control hydraulic or pneumatic servo means coupled to the rudders directly. WHAT I CLAIM IS:

1. A method of controlling, in a co-ordinated manner, a ship's twin rudders comprising displacing from a neutral position one end of a joystick pivoted on a ball mounting intermediate its ends and having its other end coupled to members pivoted on axes which are mutually perpendicular each disposed at 450 to the longitudinal axis of the ship with the members coupled to a respective servo system coupled to a respective one of the twin rudders, thereby to move the rudders to produce a movement of at least the stern of the shv in the direction in which said one end of the joystick was moved from the neutral position.

2. Apparatus installed or to be installed in a ship with twin rudders for effecting coordinated control of the ship's twin rudders comprising a joystick pivoted intermediate its ends on a ball mounting, having one end free for manual engagement and movement thereby and having its other end engaged in a respective slot in each of two arcuate members pivoted on mutually perpendicular axes each of which is disposed at 450 to the longitudinal axis of the ship, said members each being coupled to a respective servo system coupled to a respective one of the twin rudders such that movement of said one end of the joystick causes said other end of the joystick to move along the slot in at least one of said members and to pivot at least the other of said members about its pivot axis to cause the respective servo system to adjust the angle of the respective one of the twin rudders to produce a movement of at least the stern of the ship in the direction in which said one end of the joystick was moved.

3. Apparatus according to claim 2, including a pair of potentiometers, each coupled to a respective one of said members such that the voltage tapping on the potentiometers is adjusted. by movement of the respective one of said members, said potentiometers being coupled to said servo systems.

4. Apparatus according to claim 2, including hydraulic or pneumatic valves coupled to said members and opened or closed by movement of said members, said valves being connected to pneumatic or hydraulic servo means coupled to said rudders.

5. Apparatus according to any one of claims 2 to 4, including a gate to restrict movement of said joystick to within an area having approximately the shape of an angular figure eight.

6. A method of controlling, in a co-ordinated manner, a ship's twin rudders as claimed in claim 1 and substantially as hereinbefore described.

7. Apparatus installed or to be installed in a ship with twin rudders for effecting coordinated control of the ship's twin rudders substantially as hereinbefore described and illustrated with reference to the accompanying drawings.