A method of maintaining positioning between vessels includes monitoring a relative position between a storage tank vessel and a shuttle tanker with a control system in operative communication with the vessels. Also included is inputting physical property data relating to the storage tank vessel and the shuttle tanker to the control system. Further included is processing environmental condition data with the control system. Yet further included is controlling at least one positioning action to be taken by the storage tank vessel and the shuttle tanker with the control system in response to positioning calculations conducted by the control system based on the physical property data and the environmental condition data. Also included is maintaining an angular differential within a predetermined limit with the at least one positioning action.

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 are 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 are 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.

Disclosed are a canister type thruster for implementing smooth upward/downward movement and improving productivity and an installation method thereof. The canister type thruster includes a guide module for guiding upward/downward movement of a canister. The guide module includes: a guide unit that is installed on an inner surface of a trunk so as to support a rack installed on an outer surface of the canister in parallel with a lifting direction to guide the upward/downward movement of the canister; a sliding pad that relieves an impact or a fiction applied to the guide unit; and a support protrusion that is provided between the guide unit and the sliding pad to support the sliding pad.

Disclosed are a canister type thruster for implementing smooth upward/downward movement and improving productivity and an installation method thereof. The canister type thruster includes a guide module for guiding upward/downward movement of a canister. The guide module includes: a guide unit that is installed on an inner surface of a trunk so as to support a rack installed on an outer surface of the canister in parallel with a lifting direction to guide the upward/downward movement of the canister; a sliding pad that relieves an impact or a fiction applied to the guide unit; and a support protrusion that is provided between the guide unit and the sliding pad to support the sliding pad.

A method for maintaining a marine vessel at a global position and/or heading includes receiving measurements related to vessel attitude and estimating water roughness conditions based on the measurements. A difference between the vessel's actual global position and the target global position and/or a difference between the vessel's actual heading and the target heading are determined. The method includes calculating a desired linear velocity based on the position difference and/or a desired rotational velocity based on the heading difference. The vessel's actual linear velocity and/or actual rotational velocity are filtered based on the roughness conditions. The method includes determining a difference between the desired linear velocity and the filtered actual linear velocity and/or a difference between the desired rotational velocity and the filtered actual rotational velocity. The method also includes calculating vessel movements that will minimize the linear velocity difference and/or rotational velocity difference and carrying out the calculated movements.

A method for maintaining a marine vessel at a global position and/or heading includes receiving measurements related to vessel attitude and estimating water roughness conditions based on the measurements. A difference between the vessel's actual global position and the target global position and/or a difference between the vessel's actual heading and the target heading are determined. The method includes calculating a desired linear velocity based on the position difference and/or a desired rotational velocity based on the heading difference. The vessel's actual linear velocity and/or actual rotational velocity are filtered based on the roughness conditions. The method includes determining a difference between the desired linear velocity and the filtered actual linear velocity and/or a difference between the desired rotational velocity and the filtered actual rotational velocity. The method also includes calculating vessel movements that will minimize the linear velocity difference and/or rotational velocity difference and carrying out the calculated movements.

The present application relates generally to a control arrangement for controlling at least two azimuthing propulsion units of a ship. The control arrangement comprises a crash stop activation member for activating a crash stop procedure, after which the crash stop procedure is executed in which the orientation and propulsion speed of the azimuthing propulsion units are controlled until the propagation speed of the ship has at least been reduced from the moment when the crash stop procedure was activated.

A method for positioning two or more trimmable marine propulsion devices coupled to a transom of a marine vessel includes identifying two propulsion devices located one on each of a port side and a starboard side of a centerline of the transom and spaced symmetrically with respect to the centerline. The two propulsion devices are defined as a first set and are associated with a first target trim position. The method also includes defining a second set of propulsion devices and associating the second set with a second target trim position. When in auto-trim mode, each propulsion device in a set of propulsion devices is actuated to its target trim position only if the actual trim positions of all propulsion devices in the set differ from the target trim position by at least a given amount. The propulsion devices may be actuated individually in response to a user sync command.

A method for preserving electrical power in a marine vessel having a marine propulsion device. The method includes operating a variable operating device according to an original setting, measuring an actual system voltage for the marine propulsion device, and comparing the actual system voltage measured to a target system voltage. The method further includes adjusting the operation of the variable operating device from the original setting based on the comparison of the actual system voltage to the target system voltage, where adjusting the operation changes the electrical power usage in the marine propulsion device.