Both DP operating stations stopped communication – DP incident

Considerations from the above event:

• It is possible that as the vessel was only recently set up on DP, field arrival trials had not yet been completed.
• The use of DGNSS as the only position reference system for DP equipment class 2 operations is not good practice, however it is recognised that deployment of the CTD beacon could be in preparation for initiating a DP acoustic system.
• It is not clear, from the information provided, of the exact sequence of events: sensors and position reference systems are hard wired to the DP controller or Fieldnet connections, located in the DP controller cabinet, they are not connected directly to the DP OS and therefore position keeping capability should not have been affected by the OS not communicating.
• One possibility is that it was the DP controllers that stopped communicating and caused the problem; if this was the case the question should have been asked how this single point failure could have happened.
• The vessel would probably be controlled better using the independent joystick rather than individual manual control of the thrusters.
• The report suggests the possibility that the vessel returned to operations without sufficient testing to find the root cause of the problem.