According to UK MAIB’s latest Safety Digest, a davit failed catastrophically as two cadets were filling a water bag to carry out a weight test.
The incident
A ship’s workboat davits were being recommissioned after many years of lay up. The ship manager had arranged for a manufacturer’s representative to attend and oversee the davit testing process.
The ship’s C/O and the representative agreed on a weight test with a water bag suspended from the davit. The bags were to be filled to the davits’ 12t safe working load (SWL), which was 6t per bag.
Two cadets, supervised by the C/O, filled the bags using hoses from a nearby hydrant and monitored the weight with load cells on each davit head.
The water bag on the aft davit had been filled to 5.8t when the davit failed catastrophically. Fortunately, there were no injuries and the davit was later removed from the ship for examination.
Probable cause
The metallurgical examination could not conclusively determine the reason for the failure. It found that part of the davit had suffered almost 15% wastage due to rust near its failure point.
One of the sheaves at the davit head was also seized.
The examination concluded that wastage and the seized sheave may have contributed to the failure and noted that the davit structure and associated gear had not been maintained for many years.
Lessons learned
- Risk: The crew demonstrated good working practices and were standing clear of the accident site. The davit failed at less than its SWL and for indeterminate reasons. Equipment can fail without warning despite checks and precautions, which is worth considering in risk assessments.
- Margin of safety: Not standing under or near a suspended load, or its lifting gear, is good seamanship.
- Maintain: Equipment that has not been maintained for a long time may require rigorous inspection by a metallurgical engineer before being recommissioned. The equipment might need nondestructive testing as part of this process.
