ÒÁÈËÖ±²¥

1. Summary

Fatal accident to a deckhand on board the beam trawler Cornishman (PZ 512), 44 nautical miles south-south-west of the Isles of Scilly, England on 6 February 2021.

2. Narrative

At about 0630 on 6 February 2021, the crew of the beam trawler Cornishman were repairing the port trawl gear between fishing operations when the suspended steel trawl beam suddenly fell to the deck, striking and trapping a deckhand who was working underneath. The deckhand was declared deceased 1.5 hours later by the attending helicopter paramedic.

The investigation established that a 32mm Grade 8 chain link forming part of the port trawl gear’s quick-release mechanism supporting the port beam had fractured and allowed the beam to fall. The chain was operated over a 150mm diameter fixed steel pin (Figure 1) at the top of the derrick; both the chain and its links were found to be corroded, heavily worn, and cracked.

3. Safety lessons

1. Cornishman’s chain over fixed pin arrangement resulted in side loading and bending stress of individual chain links due to the low ratio between the diameters of the 150mm fixed pin and the 32mm chain link, known as the D/d ratio (Figure 2).

2. High alloy Grade 8 chains are not recommended for offshore use due to their susceptibility to environmental cracking, resulting in loss of strength and risk of catastrophic failure while loaded.

3. Chains are primarily intended for straight line point-to-point loading. Where a change in direction is required a chain lifter, such as found on an anchor windlass, or a high D/d ratio arrangement is necessary.

4. The side loading of individual chain links on Cornishman resulted in out of plane stresses, which the chain was not designed to withstand. This caused heavy wear on the fixed pin and chain links as the links were operating under dynamic loads. Alternative quick-release designs are available and should be considered as a safety improvement to minimise the opportunity for sudden failure. A safety bulletin, issued by MAIB in February 2024, provides more details.

4. Further information

Extract from The United Kingdom Merchant Shipping (Accident Reporting and Investigation) Regulations 2012 – Regulations 5:

The sole objective of the investigation of an accident under the Merchant Shipping (Accident Reporting and Investigation) Regulations 2012 shall be the prevention of future accidents through the ascertainment of its causes and circumstances. It shall not be the purpose of an such investigation to determine liability nor, except so far as is necessary to achieve its objective, to apportion blame.

Note:

This safety flyer is not written with litigation in mind and, pursuant to Regulation 14(14) of the Merchant Shipping (Accident Reporting and Investigation) Regulations 2012, shall be inadmissible in any judicial proceedings whose purpose, or one of whose purposes is to attribute or apportion liability or blame.