Some questions for all you rebreather pilots...

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Spoken like someone without much understanding of the topic. What's your CCR experience, again? And who's going to be getting down to an OC diver at 260' even? You're just as easy to assist on a CCR as on OC: either you can get off the bottom and maybe signal someone on the boat to assist with extra deco bottles via a note on your SMB, or, you can't and you're beyond help.

The main safety advantage of a CCR is time. Short of the loop failing, you have time to solve problems and time to decompress from that overstay. Read the account (pretty sure it was in Bernie Chowdhurdy's book) of a NE wreck diver who became lost in a large wreck (maybe the Stolt, I don't recall) due to a silt out.

Rather than bumble around in the dark and likely getting lost even deeper, he hunkered down on his RB and waited it out. For hours. When he could see well enough to exit, he did. On the loop, the whole way.

I have stated before that I do not dive CCR. I am very familiar with the technology and science behind it, so take that for what's it worth I guess.


Yes CCR does give you time, and people use that time as a license to go deeper. The question I answered was why nobody thinks CCR makes diving safer. I'm saying it's because it doesn't make diving safer as a whole because people tend to use the extra time as a license to do unsafe things in deep water.

No matter how much bottom time that rebreather gives you, it doesn't bring you any closer to the surface or make your body decompress any faster. Keep that in mind.
 
I have stated before that I do not dive CCR. I am very familiar with the technology and science behind it, so take that for what's it worth I guess.


Yes CCR does give you time, and people use that time as a license to go deeper. The question I answered was why nobody thinks CCR makes diving safer. I'm saying it's because it doesn't make diving safer as a whole because people tend to use the extra time as a license to do unsafe things in deep water.

No matter how much bottom time that rebreather gives you, it doesn't bring you any closer to the surface or make your body decompress any faster. Keep that in mind.

I'm very familiar with the technology and science behind a pacemaker - you won't catch me commenting on the risks involved in installing one.

You're not wrong that CCR enables going deeper, though you fail to qualifiy that with "more easily"...the depth record is still deeper on OC than CCR. Nor are people saying that CCR dives past 100m are especially safe--nothing that deep is--though they're probably safer. Realistically speaking, for what you mentioned, it doesn't matter what you're on: nobody in the non-military/commerical diving world who's going outside recreational depths is "safer" because they can be reached more easily.

Where are you getting this idea that RB divers are just dropping past the 200' range willynilly? The question you answered strongly implied that for the same dive, they felt safer on CCR vs. OC. Try answering that, not some fantasy world where people decide they'll just fill up on helium-rich hypoxic dil (usually not that simple) and drop down into serious depths because a CCR means they only have to carry 70lbs of CCR and 4-5 BO tanks, rather than doubles, 3-4 deco tanks, and a few stages.

The whole 'license to go deeper' thing is often used as a claim against non-tech certified divers carrying doubles of large HP tanks, and it's equally silly here. The dangers of a CCR involve its complexity and greater chances for human error and/or unit failure, combined with non-obvious failure modes that can kill a diver without them ever knowing something's wrong...not an magical inclination to dive super deep vs. OC tech divers.
 



1. I understand that CCR’s basically come in three flavors - eCCR or mCCR or hybridCCR… what kind do you choose to currently dive and why? Also what brand of CCR do you use?

I've been diving the MK16 (military eCCR) professionally since 2006 and currently own a Revo III Mini hCCR for personal use. The hybrid is the way to go, gives you options and redundancy. I use the solenoid as backup to my manual gas management.

2. How different do you find CCR to Open Circuit in terms of the actual diving technique ? was it a huge learning curve?

Buoyancy control is not intuitive as it is with OC. On CCR, buoyancy control is entirely dependent on equipment and not lung volume. As a result, manipulations to your equipment (adding/venting gas to drysuit/wing) are constantly required. In general this means maintaining good buoyancy/trim is less responsive and more task intensive. It can be difficult, and the learning curb is steeper relative to OC.

3. Is there anything that you still prefer in open circuit over CCR?

High current or any cardio intensive dives.

4. Finally… how safe do you find CCRs in general? are there any brands or types (electronic vs. manual) that you find safer over the other?

C
asualties resulting from CCRs are almost always human error. CCRs can be an easy ticket to a darwin award. Do your research, dive a good rig, dive smart, and maintain your equipment and you'll be fine - usually.

 
I agree with most of what Dreamdive and Dr. Lecter have said. And I wish OC divers like 2cold4california would stop opining on the technology he says he understands but has no practical experience.

Personally, I have the same rebreather that they both dive, but prefer an eCCR to the hybrid. And Claudia knows about the "refrigerator on my back" syndrome. These are all very personal preferences. The best you can do is try different ones, read the forums like RBW and CCRX, and ask questions. Contact Rod Abbotson, owner of Dive Aqaba and a real rebreather diver who is active on the forums.
 
I agree with most of what Dreamdive and Dr. Lecter have said. And I wish OC divers like 2cold4california would stop opining on the technology he says he understands but has no practical experience.

Personally, I have the same rebreather that they both dive, but prefer an eCCR to the hybrid. And Claudia knows about the "refrigerator on my back" syndrome. These are all very personal preferences. The best you can do is try different ones, read the forums like RBW and CCRX, and ask questions. Contact Rod Abbotson, owner of Dive Aqaba and a real rebreather diver who is active on the forums.
So I guess we should have to present CCR cert before we post in this forum?


What part of "practical experience" with CCR would change my perception that it is often unsafe? Using it and NOT dying? Because that is the evidence being presented in this thread is more or less "I use it all the time and I'm fine!" All the people who died were just TOO DUMB right?


The Darwin awards are often mentioned. And the sad part is somebody from this board will one day screw up, and Lecter and friends will be in here saying "no no he was just an idiot"


I'm just saying that it's dangerous. Doesn't mean you can't take the risk. And I answered a specific question posed about the public's perception of CCR as unsafe. I am perfectly qualified to answer that question, as I am part of everyone.
 
What part of "practical experience" with CCR would change my perception that it is often unsafe? Using it and NOT dying? Because that is the evidence being presented in this thread is more or less "I use it all the time and I'm fine!" All the people who died were just TOO DUMB right?


The Darwin awards are often mentioned. And the sad part is somebody from this board will one day screw up, and Lecter and friends will be in here saying "no no he was just an idiot"

If I die as a result of blatantly ignoring a faulty component, not turning on the gas supply, or not carrying adequate bailout I give you, Dr. Lecter, and all others full license to say I was dumb - and before you ask, yes all three of those instances have occurred and resulted in deaths...
 
So I guess we should have to present CCR cert before we post in this forum?

You're going a long way towards making that case, yes. But I suppose that what T2T is for.

I'm just saying that it's dangerous. Doesn't mean you can't take the risk.

You're speaking in absolutes where qualified language is necessary to avoid looking like a fool.

Anytime you go diving, you are taking signficant risks; any dive to depths deeper than that from which one can ascend on a single breath and/or where there's a deco obligation precluding direct ascent adds more risks; any dive with a hard overhead adds its own unique set of risks. None of those dives are inherently safe, or, inherently dangerous.

As between OC and CCR, the former system tends to have fewer failure points, be simpler to prepare and operate without human error, and has more obvious failure modes. The latter tends to have more things to go wrong, more steps involved in preparing for/more things to monitor and control during operation, and has multiple failure modes that can kill the user without providing an obvious problem that would draw the attention of even the most oblivious diver. Your belief they're "more dangerous" isn't without basis, but it is without context or experience -- both of which matter a lot when deciding what's relatively "more dangerous."

For a simple air dive to 200', I would agree that as between CCR with OC bailout and OC doubles/deco gas, CCR is probably more dangerous (though OC has risks CCR does not, such as greater risk of catastrophic gas loss). For the same dive inside a wreck, there is a strong argument that the smaller, bubbleless, 9+ hour duration potential CCR is safer. For ever deeper and more complicated dives, CCR offers a fixed quanitity of failure points, while OC multiplies its rather low number times every stage bottle carried...plus the complexity of the OC system as a whole increases with each added bottle/reg system, while CCR remains the same.

It all depends, which you'd know if you knew anything about CCR diving.
 
I’ve been seeing quite a few Closed Circuit Rebreathers on boats lately and finding the technology and diving approach quite fascinating. I know very little about rebreathers except for a very basic understanding of the concept and designs. I've done a search but couldn't really find any specific threads or answers to some of these questions, so perhaps some of you rebreather pilots can share your knowledge:


1. I understand that CCR’s basically come in three flavors - eCCR or mCCR or hybridCCR… what kind do you choose to currently dive and why? Also what brand of CCR do you use?
I dive an Inspiration Vision - an eCCR - for a number of reasons. It was recommended to me as a unit that demonstrably (because they were used for extended periods in Vanuatu) survive the electronics-hostile conditions in the South Pacific. It's been around for long enough to be a proven, reliable loop. And lots of people are getting rid of them and upgrading to fancier units, so you can pick one up for a decent price… Although it's an eCCR, I mostly dive it manually and use the electronic setpoint control as a back-up if I get distracted. I'm only a baby CCR diver, but I've found that my brain is much better at predicting what the loop ppO2 will be in a moment or two than the unit is, since I know what I'm about to do, so manual addition of O2 is more efficient. The electronics are handy if you're doing three things at once during an ascent, though, or get completely side-tracked by the half-dozen curious sharks circling you.


2. How different do you find CCR to Open Circuit in terms of the actual diving technique ? was it a huge learning curve?
Monstrous learning curve, as others have said. Gone - at least for the moment - are the days of unthinking, pinpont buoyancy control. And there's a lot more to monitor than just depth, time and gas: now I'm doing the rounds of cell readings, is controller 2 in synch with controller 1, do any of the cells appear to be falling out of step, am I breathing too hard, do I feel normal or is that CO2 bypass/breakthrough, why did the solenoid just fire for longer than I expected, is that gurgling noise coming from the exhale hose or counterlung (ok) or from the scrubber can (very not ok), oh, and depth, time and gas. And still having the odd buoyancy catastrophe, although they're getting further apart.


3. Is there anything that you still prefer in open circuit over CCR?
Once I get proficient enough with the CCR to just do the dives I bought it for - deep mixed-gas and overhead diving - I'll be more than happy to go back to OC for anything shallower than 180 feet or so (in the tropics), NDL diving, etc. Other than keeping motor memory current, practising skills or photographing skittish animals, I'm a bit bemused as to why anyone would want to dive CCR (relatively) shallow when they could just grab a tank or three and jump in. Especially given that post-dive care for OC is… Rinse. As opposed to sterilise, rinse, repack scrubber, dismantle head to work out why battery 2 is showing low voltage when you know it's good, etc etc.

4. Finally… how safe do you find CCRs in general? are there any brands or types (electronic vs. manual) that you find safer over the other?
As others have said, CCR safety is user-dependent. There are more ways for it to go wrong than there are with OC, but careful set-up, doing the pre-dive checklist by the numbers, carrying sufficient bailout and monitoring the system properly during the dive all help to ameliorate those risks. The kind of diver who so overestimates their abilities as to strap on a CCR and plummet off to 200 feet without proper training and experience is just as likely to put themselves in an unsurvivable position on OC, in my opinion. Arrogance and/or complacency are more likely to kill you than your chosen system for delivering breathing gas.

I merely pose these questions for my own better understanding of CCR’s and am not looking to start any debates… just interested in your own personal experiences.


Many thanks


cheers,
nasser

Answers above...
 
So I guess we should have to present CCR cert before we post in this forum?

No but those who don't know what they are talking about should maybe lose the heavy sarcasm when posting. Most of the people who have replied to did so to educate those who are following the thread. Being belligerent and condescending adds nothing to the thread.
If you just want an argument you will find a few players here but if you want to actually learn something there are also those who can help as well.
 
Thanks again to those of you have shared your first hand experience and knowledge.

I would kindly request that unless you actually have first hand experience and either own or use a CCR that you please refrain from posting your perceived impressions based on heresay rather than first hand knowledge and experience. I think there's some valuable and credible information here for people like myself looking to learn more about CCRs.

Hopefully this thread won't degenerate and go south... just don't take the bait!


cheers,
nasser
 
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