TECHNICAL FIELD 
       [0001]    This disclosure relates to automatically controlling a marine vessel in sport fishing applications. 
         [0002]    Sport fishing often involves a fisherman, or “angler”, using a rod and reel to catch a fish. The angler often fishes from a marine vessel in order to reach a favorable fishing location. When the angler has hooked a substantial fish, it can take a significant amount of effort by the entire crew to catch and bring aboard the fish. The angler engages in a tug-of-war with the fish as it changes location relative to the marine vessel. The operator of the boat must then maneuver the stern of the vessel so that it is oriented toward the fish in order to aid the angler as the fish moves. Typically such a vessel is equipped with special levers, known as “Palm Beach levers”, for steering the vessel during sport fishing maneuvers. These levers are located at the operator&#39;s station and are designed to be manipulated by the operator who faces the stern of the vessel while manipulating the levers behind him. This manner of maneuvering is hard to master and requires a skilled operator. In addition, sport fishing maneuvering can benefit from the additional thrust provided by bow and/or stern thrusters. However, controls for the bow and stern thrusters are located on a panel located some distance from the Palm Beach levers. Therefore, the operator cannot operate both the Palm Beach levers and the bow/stern thrusters at the same time. 
         [0003]    Control systems for maneuvering vessels during docking operations are known. For instance, such a system is disclosed in PCT publication WO200662416 to Ashby et al, published on Jun. 15, 2006, entitled “Propulsion and Control System for a Marine Vessel”. Examples such as Ashby et al use a bow thruster for maneuvering the vessel, but are limited to low engine speeds and are not suitable for sport fishing. 
         [0004]    Control systems for providing a special mode for sport fishing are also known. For instance, such a system is disclosed in United States Patent No. 20090,197,486 to Szilagyi et al., issued Aug. 6, 2009, entitled “Method and system for maneuvering aquatic vessels.” The example disclosed in Szalagyi et al provides for a sport fishing mode that uses high engine speed and high power, but cannot provide the additional maneuverability of bow or stem thrusters. 
       SUMMARY OF THE INVENTION 
       [0005]    A method for steering a marine vessel having a thruster system and a first and second propulsion unit is disclosed. The method comprises receiving a first signal from a left control lever corresponding to a first setting for a first propulsion unit, receiving a second signal from a right control lever corresponding to a second setting for a second propulsion unit and activating said thruster system to produce a clockwise turning moment if the first signal is greater than the second signal and a counter-clockwise turning moment if the second signal is greater than the first signal. 
         [0006]    In another aspect, a control system for steering a marine vessel is disclosed. The control system comprises an electronic controller configured to receive a first signal from a left control lever corresponding to a first setting for a first propulsion unit, receive a second signal from a right control lever corresponding to a second setting for a second propulsion unit, and activate said thruster system to produce a clockwise turning moment if the first signal is greater than the second signal and a counter-clockwise turning moment if the second signal is greater than the first signal. 
         [0007]    In yet another aspect, a marine vessel having an electronic controller is disclosed. The marine vessel comprises an electronic controller configured to receive a first signal from a left control lever corresponding to a first setting for a first propulsion unit, receive a second signal from a right control lever corresponding to a second setting for a second propulsion unit, and activate said thruster system to produce a clockwise turning moment if the first signal is greater than the second signal and a counter-clockwise turning moment if the second signal is greater than the first signal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a marine vessel and control system according to the present disclosure. 
           [0009]      FIG. 2  shows control handle functions according to the current disclosure. 
           [0010]      FIG. 3  shows a flow chart according to the current disclosure. 
           [0011]      FIG. 4  shows a second flow chart according to the current disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]      FIG. 1  shows the major mechanical components of a marine vessel  10  according to the present disclosure. The marine vessel  10  includes an operator&#39;s station  35  where the major controls of the vessel are located. Such controls include control levers  36 , a joystick  37 , thruster controls  38 , a keypad  120 , and a display  160 . The controls may be connected via a control area network (CAN)  155 . The CAN is of the type that is commonly known in the art, such as J1939. Some or all of the controls may also be located at redundant locations such as a fly bridge  40  or a remote operator&#39;s station  45 . 
         [0013]    The marine vessel  10  includes at least one propulsion unit  68 . The propulsion unit  68  includes, at least in part, an engine  50 , a transmission  55 , a propeller  80 , and an electronic propulsion unit controller  130 . The propulsion unit controller  130  may control both the engine  50  and transmission  55 , or there may be separate propulsion unit controllers  130  for the engine  50  and transmission  55 . Multiple propulsion units  68  may be controlled by a master controller  150  by connecting master controller  150  to propulsion unit controllers  130  via a control area network (CAN)  155 . The transmission  55  serves to connect the output of the engine  50  to the propeller  80 . The transmission  55  has gearing and can operate in forward, reverse, or neutral modes. 
         [0014]    Alternatively, the propulsion unit  68  may include a pod  60  instead of a transmission  55 . The pod  60  is driven by the engine  50  through a driveshaft  75 . The pod  60 , also known as an azimuth thruster, contains gearing, steering, and propulsion functions. The pod  60  is made up of two units. The first, the pod upper unit  64 , connects to the engine  50  via the driveshaft  75  and contains the gearing and steering functions. The second, the pod lower unit  66 , mounts a propeller  80  and provides an exhaust outlet for engine  50 . The pod lower unit  66  is external of the hull of the marine vessel  10  and rotates to provide steering. 
         [0015]    The marine vessel  10  includes a thruster system  90 . The thruster system  90  includes, at least in part, a bow thruster  70 , an optional stem thruster  71 , and the controllers and systems needed to control and power the thrusters  70 ,  71 . The bow thruster  70  and stern thruster  71  may be powered by motors and may be electrically driven by a controller, such as master controller  150 . The master controller  150  controls the thruster system  90  in response to inputs from the control levers  36 , the joystick  37 , or the thruster controls  38 . 
         [0016]    In another example, the thruster system  90  may be powered by a hydraulic system  100 . The hydraulic system  100  includes, at least in part, a pump driven by the engine  50 , and valves that control hydraulic flow to the thrusters  70 ,  71 . The thrusters  70 ,  71  would be driven by a hydraulic motor which may be integrated into the thrusters  70 ,  71 . The master controller  150  controls the thruster system  90  in response to inputs from the control levers  36 , the joystick  37 , or the thruster controls  38 . 
         [0017]    The marine vessel  10  contains at least one operator&#39;s station  35  that contains the helm and other functions of the vessel  10 . The operator&#39;s station  35  includes a set of control levers  36  that provide input for steering and propulsion functions. The control levers  36  include a left control lever  32  and a right control lever  34 . A joystick  37  is also included that provides fine steering and propulsion functions for operations such as docking. The speed of the engine(s)  50  is limited to a low idle setting during such operations. The joystick  37  is a two-axis input device that can control the speed of the engine  50 , gear selection in either the transmission  55  or pod  60 , and the thruster system  90 . Moving the joystick  37  to the right commands lateral movement of the marine vessel  10  to the right. Moving the joystick  37  to the forward and right commands movement of the marine vessel  10  both forward and to the right, and so on. Thruster controls  38  are also provided to control the thruster system  90 . The thruster controls  38  are typically single-axis input devices that provide individual control of the bow thruster  70  or the stem thruster  71 . The speed of the engine(s)  50  is not limited during operation of the thrusters  70 ,  71 . A keypad  120  provides keys or buttons or switches for various functions of the marine vessel  10 . Such functions could include engine start, engine mode, fuel system controls, lighting, fire suppression, HVAC, radio, blowers, anchor, bilge pump, generator control, external power, etc. The functions of the keypad  120  could also be fulfilled by a touch screen display or other input device known in the art. The operator&#39;s station  35  also includes a display  160  that shows that status of the various functions of the marine vessel  10 . Such functions could include engine status, engine mode, navigation, sonar, etc. The functions of the display  160  could also be fulfilled by a touch screen display. It is also conceived that functions of the keypad  120  and display  160  could be combined into a touch screen display. 
         [0018]    The control levers  36  include a left control lever  32  and right control lever  34  configured to control each of a left and right side propulsion unit  68 . The control levers  36  are multi-axis input devices that can control the speed of the engine  50  and the gear selection in either a transmission  55  or pod  60 . The control levers  36  can be used to control the propulsion units  68  to rapidly turn the marine vessel  10  by providing a differential turning moment in addition to the rudder. The propulsion units  68  can provide a turning moment even when the marine vessel  10  is stationary and flow forces are insufficient to allow the rudder to steer the marine vessel  10 . 
         [0019]    The control levers  36  provide an output that corresponds to a requested speed for engine(s)  50  to master controller  150 . The range is defined as 0-100% with the first half roughly corresponding to reverse and the second half corresponding to forward. The neutral position is typically located at 50% but can be varied according to the application. For instance, the forward/reverse according to the current disclosure is 50/50% but could also be 70/30%. A neutral deadband may be included that allows for approximately 15% movement from the neutral position (50%) in either direction without shifting out of neutral. For example, the output ranges may be 0-34% for reverse, 35-65% neutral deadband, and 66-100% forward. The commanded speed of the engine  50  would be proportional to the distance in either direction from the neutral deadband. The output ranges can vary according to the application. 
         [0020]    According to the present disclosure, the control levers  36  are configured to additionally control the thruster system  90  when a sportfishing mode key  170  is activated and the control levers  36  are split in their setting. The master controller  150  is configured to detect when the left control lever  32  and the right control lever  34  are moved to different positions relative to each other, thereby commanding a turning moment. The master controller  150 , upon detecting the different positions, then commands the thruster system  90  in order to provide an additional turning moment to augment the turning moment provided by the propulsion systems  68 . Unlike the joystick  37  commands used for docking maneuvers, the sportfishing mode allows for operation of the thruster system  90  when the speed of the engine(s)  50  is higher than idle. Combining the engine  50 , transmission  55  or pod  60 , and thruster system  90  controls into the control levers  36  at elevated engine speeds provides a level of response not possible with previous systems. 
         [0021]    The operator can steer the marine vessel  10  by moving the control levers  36  to different positions thereby commanding different speeds from the engines  50  and possibly a different gear (forward or reverse) from the transmissions  55  or pods  60 . The propulsion units  68  provide a turning moment that is equal to the force of the thrust from the propulsion unit  68  multiplied by the distance on the lateral axis  210  from the center of mass  220  of the marine vessel  10 . Greater thrust is available when the engine  50  is at a higher speed. Greater thrust means more response in maneuvering the marine vessel  10 . Activating the thruster system  90  further increases response. The thrusters  70 ,  71  provide a turning moment that is equal to the force of the thrust from the thrusters  70 ,  71  multiplied by the distance on the longitudinal axis  200  from the center of mass  220  of the marine vessel  10 . 
         [0022]    The marine vessel  10  may also have more than one operator&#39;s station. For instance, a redundant set of controls could be located on a fly bridge  40 . The function of the fly bridge  40  is to give a view advantageous for navigation or pleasure viewing. Another set of controls could be located at a remote operator&#39;s station  45 . The function of the remote operator&#39;s station  45  could be to give a view advantageous for docking maneuvers. The fly bridge  40  or remote operator&#39;s station  45  could therefore have at least one of a set of control levers  36 , joystick  37 , thruster controls  38 , keypad  120 , or display  160 . 
         [0023]    A fisherman, or angler  20 , typically fishes from the deck at the stem of the marine vessel  10 . Typical angling equipment includes a rod and reel. The reel includes a fishing line with an angled hook at the end for holding bait and hooking a fish  22 . The angler  20  may fish from either a seated or standing position. 
         [0024]    The sportfishing mode is activated by pressing the sportfishing mode key  170 .  FIG. 3  shows the process for activating sportfish mode and providing an indication that the sportfishing mode is active. The process shown in  FIG. 3  is executed in master controller  150 . The process starts with box  300  and proceeds to decision box  310  where the process checks to see if sportfishing mode is already active. If yes the process proceeds to action box  320  and a light on the keypad  120  is activated. The process could also activate an icon on display  160 . If no at decision box  310 , the process proceeds to decision box  330  where the process checks to see if the sportfishing mode key  170  has been pressed. The sportfishing mode key  170  could be a key on the keypad  120  or a soft key on display  160  or an icon on display  160 . If yes at decision box  330 , the proceeds to action box  340  where a light on the keypad  120  is activated and the sportfishing mode is activated. If no at decision box  330 , the process proceeds to decision box  310 . From action box  430 , the process proceeds to decision box  350  where the process checks to see if the sportfishing mode key  170  has been pressed. If yes, the process proceeds to action box  360  where the sportfishing mode is deactivated and the light on keypad  120  is turned off. The process then proceeds to decision box  310 . If no at decision box  350 , the process proceeds to decision box  310 . The sportfishing mode key  170  may be configured to be activated when pressed for at least 100 ms and deactivated when pressed for another 100 ms. 
         [0025]      FIG. 4  shows the process for activating the thruster system  90  in response to the signals from control levers  36 . The process shown in  FIG. 4  is executed in master controller  150 . The process starts at box  370  and proceeds to decision box  380  where the process checks to see if the signals from control levers  36  are above the threshold  190 . The signals from control levers correspond to the engine speed and transmission setting requested by the operator. If yes at decision box  380 , the process proceeds to decision box  400  where the process checks to see if the left control lever  32  and right control lever  34  signals are split. If yes at  400  the process proceeds to action box  410  where the control levers  36  control both the propulsion units  68  and the thruster system  90 . The process then returns to decision box  380 . If no at decision box  380 , the process proceeds to action box  390 , where the control levers  36  control only the propulsion units  68 . The process then returns to decision box  380 . 
       INDUSTRIAL APPLICABILITY 
       [0026]    The present disclosure relates to a method and control system for steering a marine vessel  10 . The marine vessel  10  is a vessel that is specially equipped for sport fishing, or angling. The marine vessel  10  includes a small crew, including a captain, in addition to the angler  20 . The captain of the ship often serves as the operator of the marine vessel  10 . The captain operates the vessel from the helm while the angler  20  is typically located at the stern of the marine vessel  10 . 
         [0027]    The operator will typically operate the marine vessel  10  in a low speed cruise mode while the angler  20  is actively fishing. If a fish  22  is hooked, the operator will typically use control levers  36 , which control the speed of the engines  50  and the direction of the transmission  55  or pod  60 . The operator can move the control levers  36  separate from each other in order to command a turning moment for the marine vessel  10  in order to keep the stern pointed at the fish  22 . The turning moment is provided by differential thrust by the propulsion units  68 . Sportfishing maneuvers require maximum maneuverability from the marine vessel  10  and therefore require large amounts of power from the engines  50 . It can be seen that the maneuverability of the marine vessel  10  would benefit from the thruster system  90  during sportfishing maneuvers. Therefore, according to the present disclosure, command of the thruster system  90  is integrated into the control levers  36 . 
         [0028]    In order to enable control of the thruster system  90 , the operator will push a sportfishing mode key  170  on the keypad  120  or the display  160 . Once the sportfishing mode is active, the controllers  130 ,  140 , or  150  may check to determine whether any sensor faults are active. If any faults are active, the sportfishing mode will be deactivated. When sportfishing mode is enabled, the propulsion units  68  and thruster system  90  work together in order to increase the steering response of the marine vessel  10 . If sport fishing mode is active and the master controller  150  detects a split, or different signal levels, between the left control lever  32  and the right control lever  34 , the master controller  150  commands the thruster system  90  to provide a turning moment to augment the turning moment provided by the propulsion units  68 . If the signal from the left control lever  32  is greater than the signal from the right control lever  34 , the thruster system  90  will provide an additional clock-wise (CW) turning moment. If the signal from the right control lever  34  is greater than the signal from the left control lever  32 , the thruster system  90  will provide an additional counter-clock-wise (CCW) turning moment. In one aspect of the disclosure, the master controller  150  may only activate the thruster system  90  if the signal from the left control lever  32  and the right control lever  34  differ by a tolerance. The tolerance may be pre-programmed into the master controller  150  or maybe user-definable and input through either keypad  120  or the display  160 . The additional turning moment from the thruster system  90  may be accomplished by using only the bow thruster  70 . A stern thruster  71 , if equipped, may provide an additional turning moment. Table 1 below further illustrates the function of the sportfishing mode according to the current disclosure. Signals are represented as percentages and are defined as in a previous portion of this disclosure. “CW” is clock-wise and “CCW” is counter-clock-wise. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Left Signal 
                 Right Signal 
                 Bow Thruster 
                 Stern Thruster 
               
               
                   
                   
               
             
             
               
                   
                 100% 
                 100% 
                 Off 
                 Off 
               
               
                   
                 50 
                 100 
                 CCW 
                 CCW 
               
               
                   
                 100 
                 50 
                 CW 
                 CW 
               
               
                   
                 0 
                 50 
                 CCW 
                 CCW 
               
               
                   
                 0 
                 0 
                 Off 
                 Off 
               
               
                   
                   
               
             
          
         
       
     
         [0029]    If the master controller  150  detects a split, or different signal levels, between the left control lever  32  and the right control lever  34 , the master controller  150  may compare the highest of the two signals to a threshold  190 . If the highest of the two signals is above the threshold  190 , then the master controller  150  commands the thruster system  90  to provide a turning moment to augment the turning moment provided by the propulsion units  68 . The magnitude of the threshold  190  is measured by determining the distance of the signal from either of the control levers  36  from the center of the neutral position, typically 50%. For instance, a 30% signal from the left control lever  32  would be equivalent to a 70% signal from the right control lever  34 . 
         [0030]    The threshold  190  ensures that the thruster system  90  will not activate during sportfishing mode unless the speed of the engine(s)  50  requested by the operator is above a certain level. The threshold  190  may be factory programmed into the master controller  150 . The threshold  190  may also be user selectable by the threshold selector  180 . The threshold selector  180  may be an input on keypad  120 , a soft key on display  160 , or an icon on display  160  if the display  160  uses touch screen technology. The threshold  190  may therefore be set by the operator according to his confidence or preference.
A marine vessel is disclosed having a control system for automatically controlling thrusters for steering the marine vessel for the purpose of aiding an angler who has hooked a fish. The control system will automatically control the thrusters based on the positions of the propulsion unit control levers if the control levers are split. The control system may also control the thrusters if the propulsion unit control levers have moved past a predetermined threshold. The predetermined threshold can be set by the operator of the marine vessel.