From: Steven Bliim
Date: Tuesday, August 31, 1999 11:40 PM
Subject: Rebreather problems?

The following is reported to have occurred in Sydney, Australia in early August. One might say that Barry should buy a lottery ticket after this one.

What a weekend! In Sydney to start my trimix course with Barry Hallett at Southern Cross, Saturday was dead flat so bugger the course we did two 48m dives with a fairly hefty surface interval, 20m viz on the Coollooli and the Dee Why.

Did some theory and mixing that afternoon, then Sunday did another 48m dive on the wreck next to the Dee Why (Meggol), on 21.5/22 Trimix, I had a lovely dive.

Barry on his Buddy Inspiration fully closed circuit rebreather however had a less than happy day (See below for the full details). At almost 50m, Barry's 'breather gave him pure O2, yup, 6.0 atm, needless to say he suffered major nausea, visual disturbances, and what he describes as like being hit with 240v, twice. He suffered two big hits but was able to make it to the surface on open circuit, negating almost 30min of deco, no signs or symptons experienced - he's a very lucky man.

Not to be outdone, his other instructor, Kosta, also on a Buddy Inspiration surfaced after a normal dive and deco, and took a mild shoulder hit of DCS, so he went down for another 20min of deco, surfaced with no other problems.

This is also after their new girl in the shop took a foot hit on Wed after a 48m dive, normal profile with the only contributing factor being she had cold feet - she's now going to buy a drysuit!

My dive went uneventfully, trimix is a lovely gas for clearing the head and focussing clearly, and completing tasks much more quickly. Looking forward to using it on the 70m dives next month, then......!

Barry's big day out: (don't read on if details bore you!)

Barry's Inspiration uses three separate electronically controlled O2 sensors and a polling method. Near the start of the dive and on the bottom at nearly 50m, one sensor went u/s, and the computer asked him if he wanted to recalibrate all three, and in his self admitted complacency, he answered yes.

He later realised the computer was asking him a question akin to "Do you want to suffer an enormous CNS O2 seizure and die, or not?" As the O2 set point for the dive was 1.4, and as he had just told the sensors that he was now only at 1 atm, and therefore PO2 of 0.21, the 'breather then commenced adding pure o2 into the loop, with the expected results of two major seizures.

He should not be alive to tell this story, as on the ascent, having bailed to open circuit, his bailout gas supply exhausted (he suspects it wasn't full to start with - error #2), luckily he had made it to the ascent line and was able to receive gas from another diver, but he continued to the surface fearing another major hit, which actually occurred. He was also not cognitive of one divers efforts to give him air, despite being right in his face.

Barry will freely admit he f___d up, due to complacency. He still has faith in the rebreather, and is not shy to tell people what he did wrong in order to let other people learn from his mistakes. Here endeth the lesson.

Steven Bliim