Experienced diver Andrew Thwaites, 44, was found dead by police divers the day after he had failed to resurface from a dive at Cherubs Cave, off Moreton Island.
Brisbane Coroner's Court heard that Mr Thwaites' cylinder contained 2366 parts per million (ppm) of carbon monoxide compared to the Queensland statutory limit of 5ppm, according to a report of the proceedings in the Sydney Morning Herald. The cylinder also contained unusually high levels of carbon dioxide.
Thwaites had signalled to his partner Kelly-Anne Masterman that he had stomach problems, and they had started to make a slow ascent, but he failed to follow her to the correct line and was thought possibly to have made a rapid ascent.
A medical expert testified that it was likely that nothing could have been done to save Thwaites once he started inhaling water, because of the damage already done by the CO gas.
Thwaites was said to have filled the tank the previous month from the compressor at the private social club of the Underwater Research Group of Queensland. Checks allegedly revealed that the cylinders of other members filled from the same compressor also contained elevated levels of the CO and CO2.
Compressor expert Bill Hunt testified that the compressor was not properly maintained and showed poor workmanship, and that ventilation in the room where it was kept was inadequate.
The inquest was told that six people were nominated as operators and could teach members how to use the compressor on their own.
The “dive captain” was said to be responsible for maintaining the compressor but according to one operator it was usually carried out by the member with the most experience. Three operators testified they were not aware of the compressor’s air quality being tested since before its last full service in 2011.
The club had no maintenance manual, the inquest heard, and some checks that should have been daily were carried out monthly, and parts that should have been replaced monthly being changed on an annual basis.
Broken gaskets were said to have been replaced with home-made seals and the compressor was sometimes run for longer than the maximum recommended time.
The compressor was said to have permanently broken down on 8 August, 2016 – two days before Thwaites’ death.
Coroner Christine Clements was expected to hand down her findings at a later date.
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