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”

Case narrative A DP2 platform supply vessel (PSV) was set up on auto DP whilst conducting trials in open water after extensive upgrades.  The redundancy concept was based on two redundant groups with power generation, thruster supplies, and all DP consumers equally split between them.  Bow thruster 1 was supplied from a dual drive which … Continue reading “Software update caused loss of generators in separate redundant groups”

  Comments from the report: A leaking seal was observed on the Port ME cooling water pump; it was replaced, and the engine tested prior to returning to operations. Considerations of the IMCA Marine DP Committee from the above event: The event report did not detail the application of any decision support tools such as … Continue reading “Leaking cooling water pump leads to – DP undesired event”

Comments from the report: The oil level gauge was not reading the actual level.  The duty Engineer did not inform Bridge/DPO`s of maintenance on the header tank of stern thruster.  Future instruction was that the engine room would inform the bridge of scope of work of any maintenance to be carried out whilst the vessel … Continue reading “Maintenance during DP operations leads to – DP undesired event”

Comments from the report: A partial blackout of the centre high voltage (HV) switchboard at 11.04am caused by No. 2 generator.  This caused the loss of the 440V distribution board and thrusters No. 3 & 6.  The centre generator No. 1 started and connected onto the switchboard, there was no loss of power to the … Continue reading “Loss of one redundant group – DP undesired event”

Comments from the report: An AVR problem in diesel generator No. 1 engine caused an over voltage in the system.  Due to increased voltage, the standby machine could not be brought online, and the switchboard required a controlled blackout.  After this, many alarms from Network B were observed due to the supply being interrupted.  An … Continue reading “Planned investigation resulted in DP incident”

Comments from the report: When the vessel was confirmed stopped and on the setpoint, the operator checked the auto track setting to find the cause of the track change.  Upon checking, it was verified that the ‘waypoint for radius turn’ had changed to ‘operator’ a pre-set value of 200m; the vessel standard setting is ‘waypoint … Continue reading “Specialised pipe laying DP mode – DP undesired event”

Comments from the report: During diving operations in open water, tunnel thruster No. 1 tripped offline.  Investigation showed that the cause was due to tripping of the thruster hydraulic pump because of voltage instability.  The voltage instability was caused by a spike load on an unrelated circuit breaker on the same switchboard which tripped.  Because … Continue reading “Loss of tunnel thruster – DP undesired event”

The IMCA Marine DP committee has identified a trend of DP station keeping events relating to the incorrect use or selection of PRSs.  Events reported to IMCA include incidents, where station keeping capability has been lost and undesired events where redundancy has been compromised. Recent Events Reported to IMCA Include the Following Learnings: Incorrect selection … Continue reading “Position reference systems – a timely reminder”

Comments from the Report The UPS and the DGNSS source does not fall under the vessel’s planned maintenance system (PMS), as this is owned by the survey company.  The equipment is maintained and tested before it is installed on a vessel.  While the testing of signal dropout and UPS function is part of the vessel’s … Continue reading “Use of third-party equipment leads to DP undesired event”