On the night between 21 and 22 December 2016, the Danish offshore supply ships MÆRSK SEARCHER and MÆRSK SHIPPER capsized and sank in the Bay of Biscay, off the French coast, while being towed by another offshore supply ship, MÆRSK BATTLER, en route to Turkey. The Danish Maritime Accident Investigation Board issued an investigation report on the accident.
The incident
MÆRSK SEARCHER and MÆRSK SHIPPER were configured in a side-by-side towing setup during the voyage. During the passage of the English Channel, the fenders between the ships on tow failed, and the ships started to interact. This caused damage to the ships’ superstructure, which eventually compromised MÆRSK SEARCHER’s watertight integrity and led to water ingress. MÆRSK SEARCHER capsized and sank, and subsequently MÆRSK SHIPPER was pulled under by MÆRSK SEARCHER. The crew on MÆRSK BATTLER carried out a controlled breakage of the towing wire and came loose of the foundered towage.
Probable Cause
The cause of the capsizing and foundering of MÆRSK SEARCHER and MÆRSK SHIPPER might seem simply to be the result of two ships being allowed to collide multiple times and a wrong choice of towing method. However, this assumption is oversimplified.
Instead, this accident calls for understanding the complex circumstances of the lengthy preparation process during a period of organisational changes, which resulted in the decision to use an unconventional towing method. In this case, the choice of towing method was made on the basis of the limitations of another tug than MÆRSK BATTLER, and there was no reason to change the towing setup to the setup recommended by external experts, as the risk connected to the side-by-side tow had been handled in the risk management system and was thereby reduced to an acceptable level.
Conclusions Actions taken DMAIB has received information from Maersk Supply Service on actions taken following the accident: Explore more by reading the full report:
