What input is necessary for automatic control of surge or sway movements on a DP system?

The correct input necessary for the automatic control of surge or sway movements on a DP system is a Position Reference System. This system provides critical information about the vessel's position relative to a fixed point on the seabed or another reference point. The accuracy of position data is essential in dynamic positioning operations, as it allows the DP system to maintain the vessel's desired position despite environmental forces such as wind, waves, and currents.

Having a reliable position reference enables the DP system to accurately calculate the necessary thrust and direction of the thrusters, thereby effectively controlling the surge (forward and backward movements) and sway (side-to-side movements) of the vessel. Without such positioning information, the DP system would not be able to compensate correctly for any movements and would struggle to maintain station, leading to potential drift from the intended position.

The other options still play a role in the overall functionality of a DP system but do not directly provide the necessary input for controlling surge and sway movements. For instance, speed feedback might provide information on the vessel's movement, but it does not directly inform the DP system regarding its precise position. Weather condition data is important for assessing operational safety and performance but is not a direct input for controlling movements. Similarly, a current measurement system can help