A young fisherman was decapitated after key safety rules weren't followed, an investigation has found.
Leighton Muir, 24, was decapitated aboard the purse seine fishing boat Captain M. J. Souza on August 14, 2014, and the Transport Accident Investigation Commission (TAIC) today released its findings into the accident.
The findings come months after the vessel's owner, Talley's Group was fined $73,520 and ordered by the Nelson District Court to pay $21,000 reparations to Muir's family.
The report said the vessel was operating in the Pacific Ocean, 650 nautical miles north of Samoa, when a nylon rope sling securing one end of the fishing net to the vessel broke.
The weight of the net was then transferred to an approximately 48mm-diameter nylon rope called a safety choker line, which was designed to retain the net end if the rope sling failed.
The crew rigged another rope to reduce the load on the safety choker line, then continued to close the net around the tuna catch.
Soon afterwards the safety choker line broke at a bowline knot that had been tied in the rope. It recoiled and struck Muir in the head.
He died instantly.
TAIC found that the safety choker rope broke because it was deteriorated, and was further weakened by the bowline knot that attached it to the net end.
It found that the broken rope was as likely as not to have begun its life in service at a lower-than-typical breaking load for a rope of that size and construction.
"However, it could not be determined why, because the rope management plan on board was not effectively managing the purchase, storage, inspection and retirement from service of the ropes on board," TAIC found.
The commission also concluded the safety management system on board the vessel provided good guidelines for the management and use of ropes on board.
"However, neither the crew nor the skipper nor shore management were ensuring that the safety management system was being adequately followed."
TAIC recommended that the vessel's operator improve its internal auditing procedures onboard.
Key lessons included tying a knot in a fibre rope to reduce its strength.
"It is therefore important to factor in this reduction in strength when tying a knot in a rope for a specific operation."
Fibre ropes could fail due to cyclic tension loading, a form of fatigue damage that could be difficult to see in braided ropes, TAIC concluded.
"Mariners must look beyond rope surface appearance alone when deciding whether to retire ropes from service."
In June, Talley's Group pleaded guilty to failing to take all practicable steps to ensure the safety of its employees while at work.
At the time, Talley's general manager Tony Hazlett said the guilty plea recognised that they were liable for the "acts of crewmen" during the course of their work.
Blame was placed on crew members for not splicing the primary line correctly and failing to assess the adequacy of the rigging.
"Neither of these officers have worked for the company since Leighton's death and have both refused to return to New Zealand and cooperate with the investigation, company, or relevant authorities," Hazlett said at the time.
Last year, Talley's was found guilty of the same charge after crewman Cain Adams died after falling 6.9m through an open hatch on the Souza when the vessel was in port in Nelson.
The company was fined $48,000 and ordered to pay $35,000 in reparations.