Accidental activation of emergency stop during saturation diving operations

What happened?

Emergency stop buttons were accidently activated on a vessel engaged in Saturation Diving Operations in the 500m Zone.  This caused the Starboard Voith Schneider Propulsion (VSP) System to trip out. 

Much happened in a single minute: at 09:27:00 DPOs noticed that a warning light on the Starboard Voith Control Station and Engine Room Control were immediately informed.  At 09:27:05 the Starboard VSP System stopped working but the vessel maintained its position.  At 09:27:14 there was a DP “Yellow” alarm.  At the same time, Dive Control was informed and started to return their Divers to the bell, and the Vessel Master and the client came to the Bridge.

Divers were safely recovered, and the vessel moved off-site and outside the 500m Zone.  There were no injuries or harm done.  The Starboard VSP System took a little under an hour to bring back online.

What went wrong?

The VSP tripped out because both lube oil pumps stopped.  Investigation revealed that the pumps were found to have stopped because both the emergency stop buttons for the pumps had been activated. 

What were the causes?

There were no protective covers on the emergency stop buttons.  The buttons were inadvertently pressed by engine room crew lacking situational awareness.  In this case, the control panels were located in a narrow access passageway.

What actions were taken?  What lessons were learned?

  • Improve situational awareness of all crew and improve/reiterate shipboard familiarisation;
  • Be reminded of position of emergency stop buttons, especially in small alleyways or spaces where there are risks of accidental activation;
  • Install covers on all emergency stop buttons;
  • More thorough job safety analysis (JSA) and toolbox talks (TBT) to be carried out covering any routine maintenance activities in Engine spaces.