One embodiment of the invention comprises a method for controlling a marine vessel having a first steerable propulsor, a corresponding first reversing device, a second steerable propulsor and a corresponding second reversing device. The method comprises receiving a first vessel control signal corresponding to a rotational movement and no translational movement command, generating at least a first actuator control signal and a second actuator control signal in response to the first vessel control signal, coupling the first actuator control signal to and controlling the first steerable propulsor and the second steerable propulsor, and coupling the second actuator control signal to and controlling the first reversing device and to the second reversing device. The method creates rotational forces on the marine vessel with substantially no translational forces on the marine vessel.

One embodiment of the invention comprises a method for controlling a marine vessel having a first steerable propulsor, a corresponding first reversing device, a second steerable propulsor and a corresponding second reversing device. The method comprises receiving a first vessel control signal corresponding to a rotational movement and no translational movement command, generating at least a first actuator control signal and a second actuator control signal in response to the first vessel control signal, coupling the first actuator control signal to and controlling the first steerable propulsor and the second steerable propulsor, and coupling the second actuator control signal to and controlling the first reversing device and to the second reversing device. The method creates rotational forces on the marine vessel with substantially no translational forces on the marine vessel.

A system for a marine vessel includes a controller in signal communication with a marine propulsion device and controlling operation of the marine propulsion device to produce thrust to propel the marine vessel at a vessel speed. A user interface receives user inputs and is in signal communication with the controller. A first sensor determines the vessel speed and is in signal communication with the controller. A second sensor determines a non-speed condition of the marine vessel and is in signal communication with the controller. In response to a given user input from the user interface, the controller controls operation of the marine propulsion device based on feedback from the first sensor to prevent the vessel speed from exceeding a maximum speed limit. The controller reduces the maximum speed limit in response to determining that the non-speed condition of the marine vessel meets a predetermined criterion.

A system for a marine vessel includes a controller in signal communication with a marine propulsion device and controlling operation of the marine propulsion device to produce thrust to propel the marine vessel at a vessel speed. A user interface receives user inputs and is in signal communication with the controller. A first sensor determines the vessel speed and is in signal communication with the controller. A second sensor determines a non-speed condition of the marine vessel and is in signal communication with the controller. In response to a given user input from the user interface, the controller controls operation of the marine propulsion device based on feedback from the first sensor to prevent the vessel speed from exceeding a maximum speed limit. The controller reduces the maximum speed limit in response to determining that the non-speed condition of the marine vessel meets a predetermined criterion.

A catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames arc spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. Each of the frames provides a space under the frame and in between the barges that enables a package to be lifted and/or a marine vessel to be positioned in between the barges and under the frames. In this fashion, an object that has been salvaged from the seabed can be placed upon the marine vessel that is positioned in between the barges and under the frames.

A catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames arc spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. Each of the frames provides a space under the frame and in between the barges that enables a package to be lifted and/or a marine vessel to be positioned in between the barges and under the frames. In this fashion, an object that has been salvaged from the seabed can be placed upon the marine vessel that is positioned in between the barges and under the frames.

A speed control device which is satisfactory in response and tracking to a speed setting, and can adjust an acceleration-and-deceleration feel according to preferences, is provided. The speed control device 6 controls a speed of a ship so that the speed automatically follows a speed setting set by a ship operator. The speed control device 6 includes a target speed setting module 63 and a change rate adjusting module 64. The target speed setting module 63 sets a target speed that is a target of the speed of the ship to follow, for every unit time, according to the speed setting, to change the target speed based on a given rate of change. The change rate adjusting module 64 decreases the rate of change by adjusting the rate of change at multiple stages, when the target speed set by the target speed setting module 63 approaches the speed setting.

A ship speed control device is provided, which includes a calculator and a throttle command value setter. The calculator calculates a throttle calculation value based on a difference between an actual ship speed and a target ship speed. The throttle command value setter sets, when the actual ship speed is below a first threshold determined based on a given throttle upper limit and the throttle calculation value is at or above the throttle upper limit, a throttle command value to the throttle upper limit.

A marine vessel control system comprises a propulsion unit and a steering actuator for steering the propulsion unit. There is a shift actuator for shifting gears in the propulsion unit and a throttle actuator for increasing or decreasing throttle to the propulsion unit. There is an input device for providing user inputted steering commands to the steering actuator and for providing user inputted shift and throttle commands to the shift actuator and the throttle actuator. There is a sensor for detecting a global position and a heading direction of the marine vessel. A controller receives position and heading values of the marine vessel from the sensor. The controller compares the received position value to a pre-programmed position value to determine a position error difference. The controller also compares the received heading value to a pre-programmed heading value to determine a heading error difference.

One embodiment of the invention comprises a method for controlling a marine vessel having a first steerable propulsor, a corresponding first reversing device, a second steerable propulsor and a corresponding second reversing device. The method comprises receiving a first vessel control signal corresponding to a rotational movement and no translational movement command, generating at least a first actuator control signal and a second actuator control signal in response to the first vessel control signal, coupling the first actuator control signal to and controlling the first steerable propulsor and the second steerable propulsor, and coupling the second actuator control signal to and controlling the first reversing device and to the second reversing device. The method creates rotational forces on the marine vessel with substantially no translational forces on the marine vessel.