Case Study: Improper securing arrangement of sea strainer cover leads to vessel capsizing

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Whilst double banked alongside another tug for four months awaiting a placement in dry dock, a harbour tug suddenly developed a list to port. Crew on board at the time quickly investigated to try and determine the point of water ingress, but struggled as the water level reached approximately 1 metre in height in the flooded engine room. As the engine room crew tried to establish and stop the source of ingress, the deck crew were adjusting the mooring ropes to keep the vessel safely alongside as the vessel listed further to port. Eventually, the master took the decision to abandon the vessel as it was no longer safe to remain on board.
A salvage operation was completed, and upon investigation, the point of water ingress was identified as a loose port side sea strainer cover.


Fuel and other oils had been removed from the vessel in preparation for the upcoming dry docking, consequently, there was no pollution from the vessel.
The deck crew were able to release the mooring ropes from the neighbouring vessel prior to abandoning, avoiding additional damage.
No personal injuries resulted from the incident.
On the port side sea strainer, only one of the eight wing nuts was found to be in place and standard nuts had been used on the other seven bolts, therefore the securing arrangement had lost most of its integrity. The bolts were also found to be rusty and general condition of the sea strainer was poor.


Completion of tasks such as securing of the sea strainer covers should be suitably supervised by a competent person as required by company procedures and the relevant task risk assessment.
Replacement spares used on critical equipment should be as-per their original design to ensure fitness for purpose.


Prompt notification of the incident allowed the Club to closely assist the Member in monitoring the claim to prevent it escalating into a wreck removal.