2016-2 – External Interface with DP Station Keeping Equipment
Learning From Incidents
A DP class 2 project and construction vessel suffered a position and heading excursion while conducting coiled tubing operations. The incident had no consequences to people, assets or environment.
The following sequence of events was reported:
• The DP system displayed a “heading out of limit” alarm and a “position out of limit” alarm.
• The vessel experienced a maximum heading deviation of 6 degree and position deviation of 4 meters.
• Bow tunnel thruster’s ramped up in response to the deviation noted on the DP system and a high force warning alarm was recorded.
• Vessel crew deselected DGNSS #1 from the DP system assuming that the excursion was caused by a DGNSS jump.
o Vessel’s crew reported that GPS “jumps” were observed on the radar an hour prior to the excursion event.
o No alarms were recorded on the DP system indicating issues with the DGNSS.
o Subsequent follow up and review of the logged data by the vendor of the DGNSS’s did not reveal any issues with the DGNSS PRS.
• Yellow limits were triggered by thruster load criteria and operations were suspended in accordance with the ASOG and vessel departed the 500 m zone.