gianaameri -
I believe you have to allow divers the opportunity to come to their own conclusions. The data and data quality concerns have run rampant on the forums for years.
You decided rebreathers are outside of your risk tolerance except when it makes sense for you to use it in a very hostile environment. If I understand your position correctly, you believe using a CCR in a cave is okay for you because logistics (read the CCR diving advantages) warrant CCR technology and you mitigate the risk (read eventuality of failure) by bringing copious OC gas on the dive. Not to be rude, but that’s the whole strategy of CCR diving for the majority of us, too. I do see value in less intense CC dives as a means of practice in OW and we seem to diverge on the topic of practice, which I find intriguing. You seem to argue less time on the loop is less likely to die, whereas I feel that I benefit from workup dives in OW before taking on overhead environments. Noted.
While it's compelling to read "Study A", "Article B", and "NEDU Result C", and anecdote Q from paragraph seven page 143, it's also reasonable [necessary] to understand [realize] people with money and time will find ways to off themselves. Anyone attaching a rebreather to their respiratory system should fully comprehend they have essentially left planet Earth. The diver has fundamentally mechanically extended their body and will be the only person anywhere breathing the precise atmosphere they're blending. We could agree that two rebreather divers on the same dive will have slightly different gas fractions, humidity, etc. in the loop at all times.
Properly trained CCR divers know what they should do to mitigate risks, the real issue here becomes are they doing it. If not, can we cause that change in the community via peer-pressure, best practices, or perhaps more fatalities - whatever else motivates change. I think what you’re asking for is everyone to agree with, "These things are as dangerous as I say they are." /pound table If that’s your objective, we get it loud and clear. Rebreathers are dangerous, especially when coupled with inadequate training, bad behaviors [plural on purpose], and lack of recent experience. You can’t decide how people will use a gizmo, or more importantly misuse a widget.
I remain interested in your thoughts, ideas, and opinions, but I think you're finding resistance here when you say - I dive a rebreather in [arguably] the most hostile environment possible, and its okay for me because I accept the risk for logistics purposes. A sentence or paragraph later you somewhat condemn your fellow divers for accepting the risk of selecting a rebreather in a less harsh environment. I recognize you may have a training/experience advantage, but these two factors, even when paired have not prevented previous fatalities as you repeatedly point out. We know that diver behaviors and disciplines have been factors in many accidents. As a community of CC divers, let’s agree to at the bare minimum eliminate bad behavior and bad discipline root causes from the list of fatalities. I acknowledge best practices will not eliminate a diver being overcome by a problem s/he could not have reacted to, or anticipate, but I do believe we can stem the tide of divers overcome by overall poor execution.
I don't want to see anyone off themselves, and I would prefer to live without ever having to pull a lifeless body out of the water again. Because of this, I take your position seriously, and with consideration, but please allow me the opportunity to make my own decisions about risk and my pursuit of diving enjoyment much as you've done. You’re not the only diver who has turned to a CCR because of logistics or environmental considerations.
If rebreathers were not as damn risky as they are, I'd dive them anywhere anytime.
As a matter of fact, I used to.
As a risk manager, however, once taking into account the information which I had been previously denied, I cannot (I owe it to myself and my 3 kids I like to play with and kiss good-night) now that I have this new information, not take it into account.
When I did my Mod 1 and purchased my first rebreather, I thought I was buying "state-of-the-art" and "EN14143:2003" technology.
It neither performed like state-of-the-art nor EN14143:2003.
I made enquiries, and discovered that it was neither of what I had based my purchase decision upon and upon which my risk assessment was based.
Then, upon further enquiries I learned more and more about the hidden risks of rebreather diving which no one explained to me and I had not understood.
It was thanks to diving doctors like Dr. Lucarini and Dr. Mitchell who went public with the knowledge that I understood - well after my Mod 3 - the "silent killer" of rebreather diving: "CO2 retention."
Rebreather diving is more risky than cave diving. Rebreather diving at any depth in any environment is more risky than cave diving. Using a rebreather in cave diving raises the risk of cave diving.
So, I do not advocate using a rebreather for cave diving either.
Logistically, and this is the key, in some caves, and this is the key, for some longer penetration dives, and this is the key, for consecutive days of diving, and this is the key, as a rare exception, and this is the key, I use a rebreather (highly modified to mitigate the residual risks inherent in out-of-the-box products).
...but I am much happier cave diving side-mount OC.
Rebreather is a tool. It is to be used where it is appropriate - that is where the benefits outweigh the risk.
I could not do the same diving on OC which I do on rebreather because of logistical constraints.
To dive a rebreather, for example, where you could do the same dive on one bottle of Air or Nitrox is simply put not appropriate (crazy risk, needless fatalities) - neither to sell it or teach it for that use or use it for that use is appropriate - till some improvements in the technology comes along.
Of course, if the user is ignorant of the true risks, than I fully understand why one would use a rebreather for recreational dives.
It is about risk management, suitability, and appropriateness.
