How great is the risk (in your perception)?

[tbone1004]

to follow up on what @KenGordon you also have to look at when the rebreather reduces overall risk even though it adds some risk on the equipment side.

How does it reduce the overall risk of a cave dive by allowing you to wait out a silt out vs having the time pressure of open circuit and "having" to get back?
How does it reduce lung stress and overall thermal stress by giving you warm and moist air vs cold/dry air?
How does it reduce the risk of ICD by easing the transition in gases that you are breathing vs the sudden shocks of gas switches on OC?
How does it reduce the logistics stress and make the overall dive safer by carrying less equipment?

sure it adds some inherent risk, but it has a lot of benefits and when those benefits outweigh the inherent risk, you should consider going to ccr?

 

[Capt Jim Wyatt]

I have read all of @tbone1004 posts here. I think he has hit the proverbial nail on the head on all of his statements.

Understanding O2 cells, how they work, how they fail and the ability to determine when one is beginning to fail is of the utmost importance- perhaps the most important aspect of CCR safety.

 

[Wookie]

I'd love to be able to use one, but they are illegal for us spearos to use.

Not in federal waters.

 

[RyanT]

I'm not a ccr diver, so I don't have anything personally to add to this discussion. However, I came across these this morning and enjoyed reading them.

East Coast Wreck Diving Long Island Dive Boat Tempest rEvo Rebreathers

East Coast Wreck Diving Long Island Dive Boat Tempest rEvo Rebreathers

 

[KevinNM]

2) User error: This suggests that the technology is not any more risky (or prone to malfunction) than open circuit but in the hands of humans it becomes riskier because it is less "monkey proof." Since more people have died using CCR (within the same depth parameters as OC) it should beg the question how come human, the same specie who is surviving OC with a higher success rate is not surviving CCR with the same success rate?

If you can breath, and didn't do something amazingly dumb, you have a safe gas mixture you can breath on OC. Particularly true when dealing with divers not running deco mixtures. There are many more subtle things that can kill you with a CCR. CO2 buildup is one, and it can be very subtle and essentially remove the ability of the diver to recognize that something is very wrong. Hypoxia can do the same thing.

I had an instructor describe a CO2 hit they took that had them lose buoyancy control and then bouncing off the ceiling a floor but didn't alarm them, it was teammates shoving regulators at them that got them to bailout. Without that the gas would have become unable to support life in short order.

There was a different diver here who years ago experienced that same effect. Solo diving rebreathers appears to me to be significantly more dangerous that solo OC.

People have died due to forgetting to turn on their eCCR. People also have gone diving without their scrubber installed. In both cases, unlike OC diving with your valve closed, there is no blatantly obvious indication that something is horribly wrong. You can breath just fine.

There are just more things that can kill you, things that you just can't have happen to you on OC. CCR allows dives that are impractical or impossible to do on OC, but there are risks.

 

[2airishuman]

I am not a CCR diver either and so it with due humility and deepest respect to other posters that I weigh in on any of this. That said, a couple of thoughts.

It is my opinion that there are many capable OC divers who do not have the aptitude to become capable CCR divers. Diving is a social equalizer in the sense that people come to the activity from all walks of life. Scubaboard is biased towards the more intellectual and articulate end of the diving community -- doctors, engineers, teachers. CCRs appeal to and are comparatively safe for this subgroup of divers. People who approach diving from a more experiential and phenomenological angle, rather than an intellectual one, are at a safety disadvantage. To @tbone1004's point, not everyone has the intellectual capacity to really understand how an oxygen cell works and why they fail the way the do. Not everyone can memorize the large decision trees that reacting to CCR emergencies require.

I think a good deal of CCR risk comes from divers having motives at odds with safety. Cost is a consideration -- are you really going to replace those 13 month old O2 cells? Are you going to replace the scrubber cartridge even though it only has xyz hours on it? Are you going to save money by packing your own scrubber? Are you going to call a day of dives on your last day of diving in tropical paradise because some yellow LED came on? It takes enormous discipline and compartmentalization to make wise choices in these areas, and not everyone can do it. I recall a couple of fatalities and lawsuits in Florida that are as much about chronic disregard for such factors as anything else.

On statistics a fact to consider is that if CCR enables dives that are not feasible on OC, and performing such dives is part of the CCR culture, then perhaps it makes sense to consider these dives part of the inherent risk of CCR in the same way that some of the hazardous bucket-list tech dives and cave dives pose risks that are part of the tech diving and cave diving landscape.

One of the shortcomings of the statistics is that CCR dives are ordinarily so much longer than OC dives that comparing accidents per completed dive is not a meaningful measure. Better to compare accidents per minute of bottom time.

 

[nadwidny]

I am not a CCR diver

Should have stopped there.

That said, a couple of thoughts.

And then you didn't.

 

[RainPilot]

Should have stopped there.


And then you didn't.

The irony....

I think @2airishuman contribution was substantially more than yours. Hell, it was more than mine.

 

[northernone]

I am not a CCR diver either and so it with due humility and deepest respect to other posters that I weigh in on any of this. That said, a couple of thoughts.

It is my opinion that there are many capable OC divers who do not have the aptitude to become capable CCR divers. Diving is a social equalizer in the sense that people come to the activity from all walks of life. Scubaboard is biased towards the more intellectual and articulate end of the diving community -- doctors, engineers, teachers. CCRs appeal to and are comparatively safe for this subgroup of divers. People who approach diving from a more experiential and phenomenological angle, rather than an intellectual one, are at a safety disadvantage. To @tbone1004's point, not everyone has the intellectual capacity to really understand how an oxygen cell works and why they fail the way the do. Not everyone can memorize the large decision trees that reacting to CCR emergencies require.

I think a good deal of CCR risk comes from divers having motives at odds with safety. Cost is a consideration -- are you really going to replace those 13 month old O2 cells? Are you going to replace the scrubber cartridge even though it only has xyz hours on it? Are you going to save money by packing your own scrubber? Are you going to call a day of dives on your last day of diving in tropical paradise because some yellow LED came on? It takes enormous discipline and compartmentalization to make wise choices in these areas, and not everyone can do it. I recall a couple of fatalities and lawsuits in Florida that are as much about chronic disregard for such factors as anything else.

On statistics a fact to consider is that if CCR enables dives that are not feasible on OC, and performing such dives is part of the CCR culture, then perhaps it makes sense to consider these dives part of the inherent risk of CCR in the same way that some of the hazardous bucket-list tech dives and cave dives pose risks that are part of the tech diving and cave diving landscape.

One of the shortcomings of the statistics is that CCR dives are ordinarily so much longer than OC dives that comparing accidents per completed dive is not a meaningful measure. Better to compare accidents per minute of bottom time.

Quality posts like this are why I'm glad we have open forums.

Cheers,
Cameron

 

[Diver0001]

I think rebreathers carry a lower DCS risk than a comparable dive on OC. That's what I see on the deco schedules when I dive with my buddies who have RB's. Moreover, your gas supply isn't as limited as OC so with respect to certain aspects of RB diving I think they have advantages.

That said, The issues I see when I observe my buddies is that it takes a tremendous amount of discipline to maintain them as opposed to OC. I also see my buddies cancelling a relatively larger number of dives because the damned thing isn't working properly. If (my assumption) other people are less careful than my buddies and try to jury rig them when there is a problem that the potential risks in that are hard to assess. I personally think that many of the accidents with vague reasons we read about have to do with this kind of thing.

As for myself, I won't dive one. It just seems to be too much work for not enough gain in relation to the type of diving I do.

R..