Rebreather diver dies in 6 feet of water - Cyprus

[Dan]

A comment made by GLOC of Andrew Fock's CCR Fatalities Paper - Published and Downloadable [Archive] - The Dive Forum

"Andrew Fock's CCR Fatality paper finally published. The data is not perfect but the best we have

http://www.dhmjournal.com/files/Fock-Rebreather_deaths.pdf

There is no one unit worse than another and the increased risk is somewhere between 4 and 10 times for CCR diving."

 

[KevinNM]

IIRC, they are comparing people diving reefs in 40 ft of water (the typical OC diver) to guys diving rebreathers in 200-300 feet in the North Sea or 5000+ feet back in a cave (more typical tech rebreather diver). So not great statistics. Rebreather diving is clearly more dangerous than diving OC at 40 feet on a reef, but is it more dangerous than diving long and deep on OC?

 

[Pinecube]

The diver was using a new closed-circuit rebreather that he had bought just before his departure. An ISC Pathfinder, it replaced an ISC Megalodon that he had used for the past nine years

What caught my eye from the news article was that he had used a new (different model) rebreather after nearly a decade of diving on his old one. I know this is a crude example but after driving my own car for years, switching to a new car has a, albiet very small, learning curve. It only takes a drive or two to get rid of some habits I developed for my old car and get used to the intricacies of the new car, but I still sometimes catch myself falling into the old habits. So I guess my question is, not being a rebreather diver, would the change in the rebreather require any significant change to habits/procedure?

 

[fsardone]

. So I guess my question is, not being a rebreather diver, would the change in the rebreather require any significant change to habits/procedure?

You have a very valid point.
I do not know the specific model(s) and how many differences there are between the two. In my case being qualified on APD inspiration vision, keeps me qualified on all APD vision machines but not on the classic.
He might as well be he was not qualified on the reb he was diving. Maybe somebody qualified on ISC rebreathers could shed some light here.
Speaking about habits, in aviation you are required a checkout on every and each different aircraft for that specific reason. For aircraft below 12,500 pounds gross weight, it is an insurance requirement, for those above and on all jets becomes a type rating required by FAA.
A very formal approach to operations is required for planes and rebreathers IMHO.

 

[reefrat]

If this guy descended only for a minute and then swam off there could have been a problem with his RB assembly or prep that had not manifest itself yet! In any case I spend as little time as possible on or near the surface when using my explorer, the solenoid is firing constantly and the unit burping frequently as it tries to maintain PPO2. As soon as I descend to 30ft it starts to settle down and then improves more with greater depth. If I am planning to do a very shallow dive (less than 30 ft) I use OC instead.
Most RB divers I know are very wary of hypoxia near the surface- especially on initial entry and then again on ascent.

 

[cathal]

Do we know was the O2 turned on?

 

[fsardone]

... In any case I spend as little time as possible on or near the surface when using my explorer, the solenoid is firing constantly and the unit burping frequently as it tries to maintain PPO2. As soon as I descend to 30ft it starts to settle down and then improves more with greater depth. If I am planning to do a very shallow dive (less than 30 ft) I use OC instead.
Most RB divers I know are very wary of hypoxia near the surface- especially on initial entry and then again on ascent.

I share the feeling that being near surface is the most dangerous place for a reb but not sure why you would have the solenoid fire continuosly and the overpressure burp.
The way to drive a CCR near surface is to shut the ADV and do an oxy flush. So the whole volume is Oxygen. When ppO2 goes below ambient means that sone nitrogen has washed out the diver body and you need a further oxy flush. At that point you keep volume by manually injecting oxygen.
When you approach 6 meters, you do a diluent flush and descent...

 

[reefrat]

"I share the feeling that being near surface is the most dangerous place for a reb but not sure why you would have the solenoid fire continuously and the overpressure burp.
The way to drive a CCR near surface is to shut the ADV and do an oxy flush. So the whole volume is Oxygen. When ppO2 goes below ambient means that sone nitrogen has washed out the diver body and you need a further oxy flush. At that point you keep volume by manually injecting oxygen.
When you approach 6 meters, you do a diluent flush and descent..."

The Hollis Explorer is an ESCR. It uses a premix of up to 40% nitrox so O2 or diluent flushes, or using a higher set point when shallow, are not options. Also, as a consequence there is no real advantage in staying on the loop on the surface so when I hit the surface on ascent I establish very positive buoyancy and get off the loop.
I only use an Explorer because logistically it makes sense where I live (no RB, no technical or even nitrox local support) and import all my own O2 then use my nitrox stick/compressor to make the gas. All my dives are with OC buddies- there are no other RB users in the country that I am aware of and all my dives are recreational depths/profiles. If the situation was different I would probably be using a Prism2 or JJCCR.

 

[fsardone]

The Hollis Explorer is an ESCR. It uses a premix of up to 40% nitrox so O2 or diluent flushes, or using a higher set point when shallow, are not options.

Sorry,
I suffer of tunnel vision. When I think rebreather I think of fully mixed gas CCR very often hCCR or eCCR.
This is because I arrived to CCR after technical path and the need to support dives in the 60-80 meters range. Threads like this remind me the there are SCR and other species of rebreather, although I am pretty sure that the casualty was on a CCR ...

 

[Kay Dee]

Sad indeed. However, OC can go wrong as quick as an rebreather, don't think OC is much safer.

No offence meant, but you can't be serious with that statement?

If I may ask do you dive OC or CCR?

As you said, whats between your ears can make you safe or unsafe, but it is a confirmed fact that CCR's are MUCH less forgiving than OC, vis a vis more 'dangerous'.

And yes, I dive a CCR, and have almost excusively for the last 18 years (and love it), and dabbled in SCR for four years before that, so although I do not profess to know everthing, I believe I have some, if only some, idea of what I am talking about.

However you of course may continue to believe whatever you want. ;-)