A crew member saw the boat in the water and tge investigation began. It was found that the release hook was still in the locked position and safety pin was in position.
Also, the master link in the hook was in good condition. It was not understood how it could have happened. The bow of the lifeboat was damaged, after a collision with a barge moored about 20m behind the vessel. The barge was not damaged.
There had been an inspection of the lifeboat earlier in the day but nothing was noticed. The inspection team did not enter the lifeboat as the maintenance hook was disabled, but no unusual hook configuration was noticed.
The vessel had in recent days come out of dry dock, when there had been an annual inspection of the lifeboat by the manufacturer. That inspection had included a check & test of the boat and the hook. At the end of the docking period, the FFB was placed back on the vessel. Thus, the vessel had a short (calm) sea voyage (1 day) to her next port.
Investigation showed no clear root cause or technical defects which might have contributed to the incident. The lifeboat was four years old and complied with all legislation and certification.
The only possible explanation is that the master link was not properly placed on the release hook, and gradually slipped out of the hook over time, IMCA reported.
- Re-assessment and careful positioning of the master link when replacing the lifeboat;
- Temporary downgrade of lifeboat safety certificate (fewer POB);
- Assessment of risk for maintenance hook to be permanently on the lifeboat when the vessel was at sea. However, it was decided not to do so, as the risk following from a more complicated emergency procedure for the crew in emergency was considered too high;
- The maintenance hook to be used always when in port, or during maintenance at sea.