Dynamic positioning control

An offshore vessel comprising a drive-off prevention controller for a dynamic positioning system, a communication system, and a propulsion system of the offshore vessel, wherein the drive-off prevention controller is configured to:

• determine a position of a vessel relative to a target position and to control a propulsion system of the vessel based on the determined position of the vessel relative to the target position;
• communicate via the communication system with at least one remote server or weather service to determine one or more indicative conditions that depend (based on page 21, line 4) on weather or environmental conditions;
• and
• selectively adjust the control of the propulsion system determined by the dynamic positioning system, based on the one or more indicative conditions;
• and
• wherein at least one of the indicative conditions comprises a demand of the propulsion system being greater than a first conditional threshold while the weather or environmental conditions received by the drive-off prevention controller indicates that there has been no corresponding change in weather or environmental conditions.

A drive-off prevention controller controlling a dynamic positioning system of a vessel, the drive-off prevention controller being configured to:

• determine a current position of the vessel;
• determine a difference between the determined current position and a target position;
• communicate with at least one remote database, at least one remote server, or a weather service to predict weather conditions;
• estimate power demand for a propulsion system of the vessel based on the determined difference between the determined current position and a target position;
• estimate a time window when a rise in power demand occur;
• operate the propulsion system:
• in a normal mode to minimize the difference between the determined current position and a target position, or
• in a limiting conditions procedure mode, wherein the limiting conditions procedure mode is applied when the estimated power demand for the propulsion system exceeds a power threshold, and the predicted weather conditions do not show a significant change during the time window when a rise in power demand occur.

A method for dynamically positioning a vessel, the method comprising:

• determining a current position of the vessel;
• determining a difference between the determined current position and a target position;
• communicating with at least one remote database, at least one remote server, or a weather service to predict weather or environmental conditions;
• estimating power demand for the propulsion system of the vessel based on the determined difference between the determined current position and a target position;
• estimating a time window when a rise in power demand occur;
• operating the propulsion system:
• in a normal mode to minimize the difference between the determined current position and a target position, or
• in a limiting conditions procedure mode when both a estimated power demand for the propulsion system exceeds a power threshold, and a predicted weather conditions do not show a significant change during the time window when a rise in power demand occur.