Method for maneuvering a marine vessel in response to a manually operable control device

A method for maneuvering a marine vessel, comprising the steps of:

• providing a first marine propulsion device which is rotatable about a first vertical steering axis which extends through a lower surface of a hull of said marine vessel;
• providing a second marine propulsion device which is rotatable about a second vertical steering axis which extends through said lower surface of said hull of said marine vessel;
• providing a first internal combustion engine disposed within said hull of said marine vessel and connected in torque transmitting relation with said first marine propulsion device;
• providing a second internal combustion engine disposed within said hull of said marine vessel and connected in torque transmitting relation with said second marine propulsion device;
• resolving a desired movement of said marine vessel into a target linear thrust and a target moment about a preselected point of said marine vessel;
• determining a first rotational position of said first marine propulsion device about said first vertical steering axis, a second rotational position of said second marine propulsion
• device about said second vertical steering axis, a first magnitude and first direction of thrust for said first marine propulsion device, and a second magnitude and second direction of thrust for said second marine propulsion device which will result in achievement of said target linear thrust and said target moment about said preselected point of said marine vessel;
• rotating said first and second marine propulsion devices to said first and second rotational positions about said first and second vertical steering axes, respectively;
• causing said first and second marine propulsion devices to produce said first and second magnitudes and directions of thrust, respectively, said first and second rotational positions resulting in said first and second marine propulsion devices producing first and second thrust vectors which intersect at a point located on a centerline which extends from a bow to a stem of said marine vessels,
• wherein one of said directions of thrust is forward thrust produced by a first rotating propeller, and the other of said directions of thrust is reverse thrust produced by a second rotating propeller, and wherein the absolute magnitudes of said forward and reverse thrusts are unequal when said propellers rotate at the same rotational speed, due to hydrodynamic effects of a propeller between forward and reverse directions of rotation,
• and comprising performing a calibration procedure comprising:
• determining a distance of length L between a line connecting said first and second steering axes and an initially presumed center of gravity of said vessel;
• aligning said first and second propulsion devices along respective thrust direction axes which intersect at said initially presumed center of gravity;
• applying said first and second thrusts to achieve expected sidle movement;
• if rotation of said vessel occurs, then assuming said length L is incorrect, and changing L to a new currently assumed center of gravity, and
• repeating the above procedure until said sidle movement occurs without rotation of said vessel about said currently assumed center of gravity, whereupon it is concluded that said currently assumed center of gravity and the magnitude of length L are correct.

A method for maneuvering a marine vessel, comprising the steps of:

• providing a first marine propulsion device which is rotatable about a first steering axis;
• providing a second marine propulsion device which is rotatable about a second steering axis;
• resolving a desired movement of said marine vessel into a target linear thrust and a target moment about a center of gravity of said marine vessel;
• determining a first rotational position of said first marine propulsion device about said first steering axis, a second rotational position of said second marine propulsion device about said second steering axis, a first magnitude and first direction of thrust for said first marine propulsion device, and a second magnitude and second direction of thrust for said second marine propulsion device which will result in achievement of said target linear thrust and said target moment about center of gravity of said marine vessel;
• rotating said first and second marine propulsion devices to said first and second rotational positions about said first and second steering axes, respectively;
• causing said first and second marine propulsion devices to produce said first and second magnitudes and directions of thrust, respectively, said first and second rotational positions resulting in said first and second marine propulsion devices producing first and second thrust vectors which intersect at a point located on a centerline which extends from a bow to a stern of said marine vessels,
• wherein one of said directions of thrust is forward thrust produced by a first rotating propeller, and the other of said directions of thrust is reverse thrust produced by a second rotating propeller, and wherein the absolute magnitudes of said forward and reverse thrusts are unequal when said propellers rotate at the same rotational speed, due to hydrodynamic effects of a propeller between forward and reverse directions of rotation,
• and comprising performing a calibration procedure comprising:
• determining a distance of length L between a line connecting said first and second steering axes and an initially presumed center of gravity of said vessel;
• aligning said first and second propulsion devices along respective thrust direction axes which intersect at said initially presumed center of gravity;
• applying said first and second thrusts to achieve expected sidle movement;
• if rotation of said vessel occurs, then assuming said length L is incorrect, and changing L to a new currently assumed center of gravity, and
• repeating the above procedure until said sidle movement occurs without rotation of said vessel about said currently assumed center of gravity, whereupon it is concluded that said currently assumed center of gravity and the magnitude of length L are correct.

A method for maneuvering a marine vessel, comprising the steps of:

• providing a first marine propulsion device which is rotatable about a first generally vertical steering axis which extends through a lower surface of a hull of said marine vessel;
• providing a second marine propulsion device which is rotatable about a second generally vertical steering axis which extends through said lower surface of said hull of said marine vessel;
• providing a first internal combustion engine disposed within said hull of said marine vessel and connected in torque transmitting relation with said first marine propulsion device;
• providing a second internal combustion engine disposed within said hull of said marine vessel and connected in torque transmitting relation with said second marine propulsion device, said first and second internal combustion engines being the sole provider of torque to said first and second marine propulsion devices, respectively;
• providing a manually operable control device which is configured to provide an output signal which is representative of a desired movement of said marine vessel;
• resolving said desired movement of said marine vessel into a target linear thrust and a target moment about a center of gravity of said marine vessel;
• determining a first rotational position of said first marine propulsion device about said first steering axis, a second rotational position of said second marine propulsion device about said second steering axis, a first magnitude and first direction of thrust for said first marine propulsion device, and a second magnitude and second direction of thrust for said second marine propulsion device which will result in achievement of said target linear thrust and said target moment about said center of gravity of said marine vessel;
• rotating said first and second marine propulsion devices to said first and second rotational positions about said first and second steering axes, respectively;
• causing said first and second marine propulsion devices to produce said first and second magnitudes and directions of thrust, respectively, said first and second rotational positions resulting in said first and second marine propulsion devices producing first and second thrust vectors which intersect at a point located on a centerline which extends from a bow to a stern of said marine vessel, said first and second thrust vectors intersecting at said center of gravity of said marine vessel when said target moment is equal to zero, said first and second thrust vectors intersecting at a point on said centerline other than said center of gravity of said marine vessel when said target moment has an absolute value greater than zero, said first marine propulsion device being located on a port side of said centerline and said second marine propulsion device being located on a starboard side of said centerlines,
• wherein one of said directions of thrust is forward thrust produced by a first rotating propeller, and the other of said directions of thrust is reverse thrust produced by a second rotating propeller, and wherein the absolute magnitudes of said forward and reverse thrusts are unequal when said propellers rotate at the same rotational speed, due to hydrodynamic effects of a propeller between forward and reverse directions of rotation,
• and comprising performing a calibration procedure comprising:
• determining a distance of length L between a line connecting said first and second steering axes and an initially presumed center of gravity of said vessel;
• aligning said first and second propulsion devices along respective thrust direction axes which intersect at said initially presumed center of gravity;
• applying said first and second thrusts to achieve expected sidle movement;
• if rotation of said vessel occurs, then assuming said length L is incorrect, and changing L to a new currently assumed center of gravity, and
• repeating the above procedure until said sidle movement occurs without rotation of said vessel about said currently assumed center of gravity, whereupon it is concluded that said currently assumed center of gravity and the magnitude of length L are correct.