Dynamic Positioning vessel (DP-1/2/3)

A dynamic positioning vessel holds its position and heading automatically using computer-controlled thrusters and propellers fed by position references such as DGPS, taut-wire, and acoustic beacons, instead of anchors. IMO MSC/Circ.645 grades the system by redundancy into three equipment classes. DP1 has no redundancy, so a single fault can cause loss of position. DP2 requires the power, thruster, and control systems split so that no single failure stops position-keeping, with automatic bus-tie separation on a fault. DP3 adds physical and fire separation by A-class divisions and separate spaces, so a fire or flood in one compartment leaves the vessel in control. Class notation rises with the criticality of the work, from supply runs to diving and drilling.