Systems and methods for orienting a marine vessel to enhance available thrust

1. A system for orienting a marine vessel, comprising:

a plurality of marine propulsion devices for orienting the marine vessel;

a control device having a memory and a programmable circuit, the control device programmed to control operation of the plurality of marine propulsion devices to maintain orientation of the marine vessel in a selected global position;

wherein the control device is programmed to calculate a direction of a resultant thrust vector associated with the plurality of marine propulsion devices that is necessary to maintain the vessel in the selected global position;

wherein the control device is programmed to control operation of the plurality of marine propulsion devices to change the actual heading of the marine vessel to align the actual heading with the thrust vector; and

a user input device that provides the control device with a signal that is representative of an operator desired movement;

wherein in a first mode the control device is programmed not to control operation of the marine propulsion devices to change the actual heading of the marine vessel to align the thrust vector with the actual heading and in a second mode the control device is programmed to control operation of the plurality of marine propulsion devices to change the actual heading of the marine vessel to align the thrust vector and the actual heading;

wherein in both of the first and second modes the control device is configured to control operation of the marine propulsion devices to maintain the selected global position of the marine vessel; and

wherein the control device is configured to determine, with a global position sensor, that the first mode is unable to maintain the global position of the marine vessel and thereafter to automatically activate the second mode.

2. The system according to claim 1 , wherein in the second mode the control device is programmed to actively maintain the actual heading of the marine vessel in alignment with the thrust vector by repeatedly calculating the direction of the thrust vector and changing the actual heading of the marine vessel to align with the thrust vector.

3. The system according to claim 1 , wherein in the second mode, when the actual heading and the thrust vector are not aligned, the control device is programmed to control operation of the plurality of marine propulsion devices to create a moment arm that causes rotation of the marine vessel about its center of gravity to thereby align the actual heading with the thrust vector.

4. The system according to claim 1 , wherein in the second mode, the control device is programmed to calculate a rotational position of each propulsion unit in the plurality of propulsion units, and a respective magnitude of thrust output by each propulsion unit in the plurality of propulsion units that are necessary to cause the marine vessel to rotate until the actual heading of the marine vessel and the thrust vector are aligned.

5. The system according to claim 1 , wherein the user input device is configured to allow an operator to select between the first and second modes.

6. The system according to claim 5 , wherein the user input device comprises a joystick.

7. The system according to claim 5 , comprising a compass device that provides a signal representative of actual heading of the marine vessel to the control device.

8. The system according to claim 5 , wherein the actual heading is the longitudinal direction in which a bow of the vessel is directed.

9. The system according to claim 5 , wherein aligning thrust vector and the actual heading causes an output thrust of each of the plurality of marine propulsion devices to be aligned with the actual heading.

10. The system according to claim 5 , wherein the plurality of marine propulsion devices comprises first and second marine propulsion devices.

11. A method for orienting a marine vessel, comprising:

providing a plurality of marine propulsion devices coupled to the marine vessel;

selecting a global position of the marine vessel;

determining an actual heading of the marine vessel in the global position;

providing a control device having a memory and a programmable circuit, wherein the control device controls operation of the plurality of marine propulsion devices in first and second modes;

operating the control device in the second mode to

(a) control operation of the plurality of marine propulsion devices to maintain the global position of the marine vessel;

(b) calculate a direction of a thrust vector associated with the plurality of marine propulsion devices, which is necessary to maintain the global position of the marine vessel; and

(c) control operation of the plurality of marine propulsion devices to change the actual heading of the marine vessel to align the direction of the thrust vector and the actual heading;

selecting between the first and second modes of operation wherein in the second mode the control device controls operation of the plurality of marine propulsion devices to change the actual heading of the marine vessel to align the thrust vector and the actual heading and in the first mode the control device does not control operation of the plurality of marine propulsion devices to change the actual heading of the marine vessel to align the thrust vector and the actual heading;

controlling operation of the marine propulsion devices in both of the first and second modes to maintain the selected global position of the marine vessel; and

determining with a global position sensor that the control device in the first mode is unable to maintain the global position of the marine vessel and thereafter automatically activating the second mode.

12. The method according to claim 11 , comprising, in the second mode, controlling operation of the plurality of marine propulsion devices to create a moment arm that causes rotation of the marine vessel about its center of gravity to thereby align the actual heading with the thrust vector.