The report concluded that the DPO was conducting too many concurrent tasks so that he did not sufficiently monitor the vessel speed during the time the vessel was being controlled with JSAH. Further to this, company procedure/standing instruction have been changed so that changing the position of the targeted waypoint can be avoided except in the most necessary of cases. If it is found necessary to change the waypoint position, then the ploughing operation should be temporarily suspended by stopping the vessel and selecting automatic DP.
Considerations from the above event:
- It would be of considerable benefit if plough pulling forces, which can vary greatly, were fully integrated to the DP. It is not clear if this was the case and whether the direction of forces was interfaced;
- It appears that a proper evaluation of the operation was not made: familiarity of the system is required together with adhering to company procedures;
- A proper understanding of the relationship between position reference systems and forces is required;
- Consideration should have been given to reduce speed to the operational minimum, the slower the progress of the plough the less effect it will have on the vessel’s positioning capability, as inertia becomes less effective.
The following case studies and observations have been compiled from information received by IMCA. All vessel, client, and operational data has been removed from the narrative to ensure anonymity.
Case studies are not intended as guidance on the safe conduct of operations, but rather to assist vessel managers, DP operators and DP technical crew in appropriately determining how to safely conduct their own operations. Any queries should be directed to IMCA at [email protected]. Members and non-members alike are welcome to contact IMCA if they have experienced DP events which can be shared anonymously with the DP industry.
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IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall not be liable for any guidance and/or recommendation and/or statement herein contained. The information contained in this document does not fulfil or replace any individual’s or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.