From where is Sway data primarily derived on a DP vessel?

Sway data on a Dynamic Positioning (DP) vessel is primarily derived from Position Reference Systems. These systems are essential for determining the movement and position of the vessel in relation to its intended position. Sway refers to the lateral movement of the vessel, which can be caused by environmental forces such as wind, waves, and currents.

Position Reference Systems include various technologies, such as Global Navigation Satellite Systems (GNSS), laser systems, and acoustic positioning systems, all of which provide critical data to the DP system. By processing this information, the DP system can determine the extent of sway and make necessary adjustments to maintain the vessel's position.

Other potential sources of information, like navigation charts, thruster output readings, and environmental sensors, provide different types of data that can assist the DP system, but they do not primarily focus on measuring sway. Charts give a static view of the area and obstacles, thruster output reflects the vessel's thrust capabilities, and environmental sensors monitor external conditions but do not directly measure lateral movements. Hence, the primary source for sway data is indeed the Position Reference Systems.