A computer-controlled system that automatically maintains a vessel's position and heading using thrusters, without anchoring.
In practice
Class 2 DP is required for operations where a loss of position would be catastrophically hazardous, such as pipe-laying or diving support near a subsea wellhead. Class 3 adds fire and flood separation between redundant DP systems. Marine engineers on DP vessels must maintain all thrusters, power management systems, and position reference systems to the standard required by the DP class notation, and any failure to maintain the prescribed redundancy must be recorded in the DP incident log and reported to the client and certifying authority. Annual DP trials witnessed by an independent DP assurance body are normally required to maintain the DP class notation.
Regulatory detail & full definition
Dynamic positioning is an automated station-keeping system that uses a computer to process position reference signals from GPS, differential GPS, acoustic transponders, and taut-wire sensors, together with environmental inputs from wind sensors, motion reference units, and gyrocompasses, to calculate and apply thrust commands to propellers and thrusters so that the vessel maintains a preset position and heading without anchoring. DP systems are classified by the IMO in MSC/Circ.645 into Equipment Class 1, 2, and 3, based on the level of redundancy provided against equipment failure during critical operations.
Class 2 DP is required for operations where a loss of position would be catastrophically hazardous, such as pipe-laying or diving support near a subsea wellhead. Class 3 adds fire and flood separation between redundant DP systems. Marine engineers on DP vessels must maintain all thrusters, power management systems, and position reference systems to the standard required by the DP class notation, and any failure to maintain the prescribed redundancy must be recorded in the DP incident log and reported to the client and certifying authority. Annual DP trials witnessed by an independent DP assurance body are normally required to maintain the DP class notation.