A hydrodynamic system which controls or maintains the position and heading of the vessel by centralized manual control or by automatic response to the variations of the environmental conditions within the specified limits. DP system comprises the sub-systems:
- power system,
- thruster system, and
- DP-control system.
DP systems are divided into three classes:
DP1 has no redundancy. Loss of position may occur in the event of a single fault.
DP2 has redundancy so that no single fault in an active system will cause the system to fail. Loss of position should not occur from a single fault of an active component or system such as generators, thruster, switchboards, remote controlled valves etc., but may occur after failure of a static component such as cables, pipes, manual valves etc.
DP 3 also has to withstand fire or flood in any single compartment without affecting the system. Loss of position should not occur from any single failure including a completely burnt fire sub division or flooded watertight compartment.
Further reading: IMCA Guidelines for The Design and Operation of Dynamically Positioned Vessels, ABS Guide for Dynamic Positioning Systems