Mark,
I have spoken to Howard about this. His recollection which I use as a case study for Human Factors in Diving Incidents was different to what you recount.
He didn't have a CO2 hit but was working hard and was still having head games from his CO2 hit 3 weeks previously. He bailed onto his Al80 as he thought he was having a CO2 hit and made the rapid ascent when he realised that he was going to run out of gas. He didn't use the reg that his buddy offered to him. He ran out of gas approximately 30m and changed to 50% knowing he was going up quickly. He lost control of the ascent and flooded his loop to stop him hitting the surface (good move).
Sending a bag up to get more gas was a good thing.
AFAIK, he and his buddy have a much more conservative view on buddy skills now.
You keep saying that people can't keep up that level of breathing and yet there are those who have.
The consensus appears that if you are going to ignore CO2 hits, then you can carry enough bailout at depth for you because you are unlikely to have elevated breathing rates. However, if you are going to try and mitigate CO2 hits, then you are not going to have enough gas once you get down much past 60-70m.
Regards
Let me give you a few facts about the dive and perhaps you can possibly have a re think on the case.
Howard and j were diving as a pair and i was diving with George. George had a scooter failure so we ended fining. Howard and j were scootering.
We all met up on the bottom and were looking for the big guns but viz was poor and we only found one of the small ones. Howard and I had an underwater hand signal discussion about where we should be looking and he at that time seemed perfectly lucid and happy. I had dived over 100 dives with Howard at that time and I noticed nothing about him at that moment to suggest he was in trouble. J can confirm but apart from a course we all did together I don’t think J had more than 5 -10 trimix dives with Howard before this trip.
We separated and George and I headed for the shot. Only on ascent when we discovered Howard and Js tag still on the line did I realise there was a problem.
After the event I talked in great detail to Howard about what happened. He was bunking with me and George with J. The over whelming thing was his feeling of impending danger, his stress and his feeling of being overloaded by the scooter and the dive in general. Classic paranoia symptoms of narcosis. But he had a shed load of He in his mix so narcosis shouldn’t have been an issue. Add to this that for some time he’d been complaining about the WOB of his Mk1 Golum BOV. These Mk1 units were truly awful. I was told that in testing (so you can guess who told me) that the Mk1 Golum was 200% higher WOB than than the JJ BOV in CCR mode.
I had got the Golum Low Work of breathing kit for my BOV and it had made a significant difference which you didn’t need a machine to notice. I had tried to convince Howard to get one.
Have a chat with Rob Dobson about his feelings of WOB on the Mk1
J told me that he was trying to end the dive but Howard wasn’t following him back to the shot. Howard was in fact scootering off out into the blue. Repeated attempts to get Howard to come back to the shot failed and it was decided to go up. In the attempt Howard did a rapid ascent and J lost contact with him.
So now we have an overview of the incident.
J for reasons which baffle me, is convinced it wasn’t a C02 event. Howard didn’t remember much about the end of the incident prior to the rapid ascent when we talked about it at the time.
Personally I see it as odd that a diver I have dived with for years and one I’d describe as being positively chilled out under water even in extreme conditions, suddenly has a panic attack.
The previous trip to Malin Howard and I dived together every dive and as usual he was relaxed. On the last dive of the trip we did a freighter in 65m on the Scottish side and Howard and I went down the shot together fighting against the current all the way. Conditions were incredibly tough and most of the other divers aborted the dive. Once at the bottom Howard was panting hard and also decided to bin the dive. He went back up and I carried on solo. No drama no big issue but then that year Howard didn’t have the Golum BOV he had the standard Inspo mouthpiece.
From Js description of events Howard became unresponsive to suggestions and was scootering erratically off in the wrong direction. When offered help he didn’t take it.
J had very little experience of deep diving with Howard so perhaps this is why his conclusions are different from my own but I can tell you Howard is in the water as he appears to you and I on land, a calm diver who’s not easily flustered and treats most situations as a laugh. Possibly his recent run in with C02 (missing 0 ring on the scrubber) had a significance but id suggest that was to induce the bad narcosis trip rather than the happy mermaids narcosis.
The only explanation I can offer for Howards reaction under water is narcosis as a result of elevated C02 levels brought on by working too hard at depth against a Golum BOV with a very poor CCR WOB.
Scootering is supposed to be less work than fining but anyone who’s tried scootering for the first time will tell you that its bloody hard work till you get it right.
Nothing about the incident suggests a panic attack. The loss of buoyancy could, but not the erratic behaviour leading up to this event. I was adamant then it was a retained C02 event and j was adamant that it wasn’t, but I don’t know what he’s basing his premise on.
As for the revision of buddy skills since this incident? I love to know what j could have done differently? Short of going up with Howard I am sure he did his best.
This was in September 2009 and I very much doubt if j has dived with Howard more than a dozon times since then. Howard usually dives as a three with J and I and he’s done 4 trimix dives with us in the last three years. On all of those dives I have no knowledge of any change in our working practices.
ATB
Mark
is because; 1) high CO2 pre-disposes to oxygen toxicity and 2) it allows for simplicity through diluent matching (simply computer switch to OC, no gas swap).
