Think twice. Press once!

The DP equipment class 2 supply vessel was engaged in geotechnical drilling activities, operating in open bus configuration with two generators and four thrusters online. The weather conditions were good with a DP current registered at 2 knots, the DP system fully operational and the Bridge & DP station fully manned as per requirements. The vessel was using two DGNSS, one taut wire and one HPR for position referencing to the DP system.

The vessel had been at the location, on DP for over six hours and performing drilling operations. The SDPO had just notified the ‘Doghouse’ of the increasing water current. There were no active alarms on the DP control system and the vessel footprint was good. As the SDPO was monitoring the desk he noticed the Mode Selection turned grey and all thruster selection tick boxes went blank, as the DP alarm activated.

All thrusters simultaneously dropped out of DP and the vessel began rapidly losing position.

The Master instructed the SDPO to activate the Amber DP Alert light, which was subsequently raised to Red.

During the investigation, it was noted that a member of the Bridge Team was conducting planned maintenance on the Bridge Navigation Watchkeeping Alarm System (BNWAS). The task entailed testing all the systems alarm reset buttons, of which two are located on panels on the Bridge Wings.

• On the port Bridge Wing the crew member accidentally pressed the Mode Selector ‘Em Manual’ button rather than the Bridge Watch alarm reset button.
  
  
• The Em Manual button reverts all thrusters from DP to Manual Mode.
  
  
• The Master took command from the SDPO, attempting to re-establish DP control. It was determined that the thrusters were operational and able to be controlled using manual controls.
  
  
• Master slowed the vessel’s drift using manual controls.
  
  
• The SDPO communicated the Red DP Alert to the ECR and ETO.
  
  
• The crew member performing the maintenance spoke with the SDPO and explained which button had been depressed. The SDPO confirmed that the emergency system had been activated and reset the button.
  
  
• The DP control was reinstated but the vessel drifted 94.5 m from the DP setpoint. As a result, equipment damage occurred.

Following investigations, it was determined that the incident occurred due to lack of operational knowledge.

Only qualified and authorised personnel may operate or modify system controls. No button, switch or setting should be activated without a complete understanding of its function and impact on vessel operations.

In order to mitigate the risk of a future re-occurrence, the vessel held further training to all Bridge Team members on the BNWAS system and to all vessel members on the importance of not pressing, switching or changing controls unless they have full understanding of the function and its potential consequences.

The vessel fitted a perspex cover with additional warning labelling across the mode selector panel, to further eliminate possible accidental activation.

Remember before pressing any button, flipping any switch, or changing any setting ask yourself:

• Am I qualified and authorised to do so?
  
  
• Do I understand the exact function?
  
  
• Do I know the potential impact on the DP system or vessel?