Comments from the report:
The error was traced to a serial interface module for DP Controller A and confirmed that the red error lamp on this module was illuminated. Whilst indicating an error, the module was still performing correctly in so far as there was no effect with its data feeds. The decision was made to replace the module with a new one, dive control was requested to recover the bell to surface and hold it there whilst replacement was carried out.
Considerations of the IMCA Marine DP Committee from the above event:
- The actions taken were all in accordance with good practice.
- 40m water depth only provides for a small envelope for seabed based position reference systems (PRS).
- In these depths of water, it is advisable to make use of surface based PRS, in this instance DGNSS was used.