Shackle failure on a luxury motor yacht
A large, UK registered luxury motor yacht was on charter and was berthed “stern to” in a Mediterranean port. The guests had completed their water sports for the day so the vessel’s tender was sent to collect them. They were then disembarked onto the diving platform on the vessel’s stern. The tender was then positioned immediately below the vessel’s crane, which was used to hoist the tender and transfer it to its stowage position on the sun deck.
The eye of the three-legged strop (Figure 1) was connected to the crane hook and the coxswain attached each of the spring hooks (Figure 2) to the tender’s lifting points. The coxswain remained in the tender as it was hoisted about 500mm clear of the water. This was to ensure that the spring hooks were correctly positioned as the crane took the weight.
He then prepared to disembark into another of the vessel’s small boats so that the tender could
be hoisted the remaining 8 metres to its stowage position. As he was about to leave the tender,
one of the spring hooks catastrophically deformed (Figure 3). The tender, now supported
by only two hooks, became unbalanced and the coxswain was thrown into the sea. The coxswain was uninjured.
The crane and lifting strop arrangement were all in date for test. However, the combined weight of the tender and the coxswain put the arrangement close to its Safe Working Load
(SWL). The situation was likely to have been further exacerbated by wash from other vessels
causing the tender to “snatch” at the strop and probably prompting the deformation process.
None of the yacht’s team had conducted or were familiar with risk assessment procedures.
However, precautions were taken: surplus weight had been removed from the tender, and the
custom and practice was for the crew to leave the tender as it was hoisted.
The Lessons
Although not documented, a mental risk assessment had been undertaken, and some of the risks associated with hoisting the tender with crew on board had been recognised. However, no one appeared to realise how close to the SWL they had been operating, and what effect the additional “snatching” would have on the system. Had the snap hook failed when the tender was at its highest lift of 8 meters, with someone onboard, the outcome would have been very different.
1. Risk assessments are an essential mechanism in identifying those activities that require control measures to be put in place to prevent the likelihood of an accident. They should be regularly reviewed to ensure their currency.
2. Crew should not be permitted to remain in a lifeboat for any longer than necessary during the lowering or hoisting procedures.
3. Regular examination and testing of lifting equipment is an essential element of safety management and risk reduction.
4. Due account should be taken of the likely additional weights on board boats/tenders and the “snatching” effect of the boat’s motion when considering
the suitability of the SWL of related lifting equipment.
Reproduced by kind permission of the Marine Accident Investigation Branch. Originally published in MAIB Safety Digest 2/2005.
www.maib.dft.gov.uk
