A DP System is a computer-based control system used to automatically maintain a vessel’s heading and position without the use of mooring lines and/or anchors. Horizontal movement of the vessel is controlled on 3 separate axes:

  • Surge (fore and aft)
  • Sway (side-to-side)
  • Yaw (heading)

System computers receive input from various sensors to determine the external forces being applied to the ship. This information is then processed to determine the amount and direction of force that must be applied by the vessel in order to maintain the required position and heading. Thrusters then execute the commands given from the system and exert the desired force.


Finally, a vessel’s DP system uses 7 onboard elements in order to control horizontal movement of the vessel:

  • Position Reference Systems: The PRS identifies the vessel’s current location and compares it to the desired location.
  • Environmental & Motion Sensors include: Motion sensors; Wind sensors; Compass; Tension Sensors
  • Power System: An arrangement of mechanical and electrical equipment that provides power to the Thruster/ Propulsion system in order to maintain position.
  • DP Controller: The “brain” of the DP system
  • Thrusters/Propulsion System: Thruster/Propulsion systems are arranged to provide adequate thrust for maneuverability and maintaining position.
  • Human-Machine Interface: Here the operator is capable of commanding the DP system, monitoring for alarms, as well as manually controlling thrusters if necessary.
  • Human Element (DP Operator): He or she inputs the desired course/ heading/location in the system and monitors the system’s ability to execute the desired command.