Case narrative A DP2 cargo vessel was working close to a pipelaying vessel conducting cargo operations in a drift off position.  The current at the time of the event was 2.5 knots which, in conjunction with 10 knots of wind, resulted in an external force of 30 tons acting on the port quarter. The port … Continue reading “Steering motor failure leads to loss of both aft thrusters – DP incident”

Comments from the report Whilst pressurising the fire main for helicopter operations, a gasket failure occurred on the pipework valve under the engine room floor in front of transformers 690V/440V T3 and T4.  The spray created a water fog and favourable atmosphere for an electric arc on T3 and T4 transformers, leading to a loss … Continue reading “Pipe leak leads to loss of all thrusters – DP incident”

Case narrative A DP2 ROV support vessel was working close to a metrological (met) mast within a wind farm.  With ROV work completed, the project instructed the vessel to be relocated from the East to the West side of the mast for further ROV duties. The current at the time of the event was around … Continue reading “Vessel rotation leads to loss of position – DP incident”

Comments from the report Only 2 DGNSS were online, with poor signal quality due to the location and environmental conditions.  The end effect was that the deviation from the set point in surge and sway were increasing for each oscillation. Considerations of the IMCA Marine DP Committee from the above event For DP2 operations, the … Continue reading “Unreliable position reference systems leads to DP incident”

Case Narrative: A DP 3 6th generation drillship was set up on automatic DP engaged in plug and abandonment operations in field.  The DP design concept of the vessel was such that there were two redundant groups and the vessel was set up with power generation and thruster supplies equally split across each redundant group … Continue reading “DP3 drillship switchboard blacked out – DP undesired event”

Comments from the Report: It was considered that the movement towards the drill ship could have been caused by a combination of position reference system degradation and interaction from the Drill ship’s thrusters.  There was an advisory regarding service disruption from the DGNSS supplier in force at the time.  It was stated that the DPO … Continue reading “Mix of absolute and relative position reference systems – DP incident”

Comments from the Report: The vessel was experiencing heavy rolling and pitching.  The watch keeping engineer lost his balance and his hand made contact with the No. 2 shaft generator breaker push button, thus opening the breaker and causing the loss of power.  The vessel has installed transparent covers over vulnerable breaker push buttons to … Continue reading “Accidental breaker trip – DP undesired event”

Comments from the Report: The vessel maintained position but DP equipment class 2 capabilities were compromised.  It was noticed that there was a strong burning smell from the UPS.  The UPS was still powered up from the ships supply but it was in internal bypass.  Tests were carried out and it was noted that there … Continue reading “Failure of DP UPS – DP undesired event”

Comments from the report: Although DP checklists were completed, the availability of the standby operator station was not confirmed.  The most probable cause for DPOS2 to freeze and not auto changeover was traced to a faulty IO controller on DPOS2.  The vessel replaced the controller with a spare held on-board.  At the time of the … Continue reading “Operating outside DP equipment class 2 requirements – DP incident”

Comments from the report: Both DPOs had several years’ experience but with a different DP control system where it is common to stop the vessel during a move by reducing speed to 0.0kts.  However, on the system fitted to this vessel a retardation factor is used so speed is reduced automatically when the stop request … Continue reading “Unfamiliarity with DP system leads to – DP undesired event”