Dynamic positioning (footprint)

A dynamic positioning footprint is the scatter of position excursions a DP vessel holds around its setpoint under a given environment, usually quoted as a watch-circle radius or an ellipse of the position cloud. It results from the thrust the propulsion can muster against wind, current, and wave drift, mediated by the DP controller and reference systems such as DGNSS and taut-wire. A tight footprint of a few meters is needed for diving and drilling; the footprint widens with environmental load until thrust saturates and station-keeping is lost. Footprint plots are a standard acceptance deliverable for DP capability and FMEA trials.