A Comparison-contrast Of Available Rebreathers

[Gill Envy]

Additionally, the doggie came through with flying colors regarding his "rebreather" exercise.

X

I can’t help but to ask… was your doggie diving an mCCR? Part joke- part serious. I can pretty much guarantee he was. My father in law is an anesthesiologist MD and when I posed the question to him about weather rebreather technology in medicine is going in the direction of automation, he said that while there are advancements in the monitoring systems occurring constantly, that the actually maintenance of gas balance is still left to the judgment of the operator. He believes that that is unlikely to ever change because no machine is better at maintaining the life sustaining mix. Could the same apply to rebreathers for diving? Food for thought.

Just adding to the piece above...safety should be the focus of all rebreather education. Vetting a student is an important first part of the process, as is coursework which ensures a consistent level of proficiency. In my recent experience, the vetting and fulfillment of standards is somewhat variable. No surprise there as the pool grows, gets diverse and standards diluted.


MCCR accidents will grow as more users enter this niche of the RB diving, and as some push their units harder. I also believe that MCCR users are far more cognizant of the nuances in oxygen addition and their metabolism...which translates to being aware most of the time. ECCR guys can get complacent. I know I do when it comes to video work. This is why I choose to have someone supervise me, as I become myopic.

Since I dive all sorts of RB units I have no favorites. Each one does what its supposed to, and I try to keep pace with each of the units needs. I do fly the ECCR manually most of the time, as a result of using an MCCR. I think its good practice.X

What I think is missing is an objective third party review board that has no connections to the industry or financial gain to be made from their stance. Getting an impartial analysis of risk factors, accidents and design would be a big step forward.

Reported experience of divers themselves, experience and opinions of instructors and certifying agencies and of course the innovations of manufacturers, while all are valuable, all are biased by their very nature.

Some examples: Divers have a tendency to praise the particular unit they have and put down the last one they had. It’s in the best interest of instructors to be as open to multiple styles and brands as possible to attract the broadest base of students in this very small and competative niche market of rebreather instruction … and Manufacturers are obviously beholding to their proprietary interests.

We need a way to see past all the partiality and develop an objective system for data collection and analysis and manufacturers need to get over themselves and open their books for a real numbers comparison.

Until we have a unbiased, impartial source of analysis and a standard for data collection we are left to extrapolate and speculate. For now we are left with a pile of numbers that I’m tempted to treat as a type of outcome study for lack of anything better to go on. I’ve done my best to identify patterns but in reality I know they are inconclusive.

So far the most attractive logic all too often seems very paradoxical and potentially misleading when it comes to rebreathers. Those wanting to determine risk factors must look deeply below the surface.

For an example of just one instance of the convoluted, anti intuitive state of things, you suggest that the risk of accidents on mCCR will go up as people push them more. That seems very logical but I’d don’t see support for that in outcomes, not so much even for eCCR’s. the number of mCCR divers and the level of challenge of dives performed on them appears to have been going up for some time now and still, no increase in fatalities. And While it seems logical that the more one pushes their unit, the more at risk one would be, but the numbers seem to suggest a counter force in trends. As is the case in so many aspects of rebreather diving there is a surprising twist that seems to turn the equation on it’s head… from what I can see many of the accidents occur on relatively routine dives by relatively experienced divers (and on eCCR’s nearly exclusively), not in the envelope pushing zone or much by beginners either. Some even happen in swimming pools. I would suggest that the more challenging a dive is perceived to be, the more attention gripping it is, and that could be leading to the added risks being overcompensated for by the added vigilance (before and during the dive)…conversely lowering the fatality rate on more demanding dives.

To extrapolate further, it would seem more logical that as mCCR’s are used in more envelope pushing dives that the risk of fatality goes down even further, not up, on such dives since they inspire greater vigilance all the more. Inspiring vigilance on a routine dive is harder to build into the system of an eCCR where a diver tends to be more relaxed. Relatively routine dives are where the fatalities seem to happen most and where I believe being forced to remain vigilant will save lives more effectively than trying to remind ones self to remain vigilant when there is not a consistent need. If there is a better way of achieving that than manual injection than I’m all ears.

g

 

[Mr.X]

I can’t help but to ask… was your doggie diving an mCCR? Part joke- part serious. I can pretty much guarantee he was. My father in law is an anesthesiologist MD and when I posed the question to him about weather rebreather technology in medicine is going in the direction of automation, he said that while there are advancements in the monitoring systems occurring constantly, that the actually maintenance of gas balance is still left to the judgment of the operator. He believes that that is unlikely to ever change because no machine is better at maintaining the life sustaining mix. Could the same apply to rebreathers for diving? Food for thought.



What I think is missing is an objective third party review board that has no connections to the industry or financial gain to be made from their stance. Getting an impartial analysis of risk factors, accidents and design would be a big step forward.

Reported experience of divers themselves, experience and opinions of instructors and certifying agencies and of course the innovations of manufacturers, while all are valuable, all are biased by their very nature.

Some examples: Divers have a tendency to praise the particular unit they have and put down the last one they had. It’s in the best interest of instructors to be as open to multiple styles and brands as possible to attract the broadest base of students in this very small and competative niche market of rebreather instruction … and Manufacturers are obviously beholding to their proprietary interests.

We need a way to see past all the partiality and develop an objective system for data collection and analysis and manufacturers need to get over themselves and open their books for a real numbers comparison.

Until we have a unbiased, impartial source of analysis and a standard for data collection we are left to extrapolate and speculate. For now we are left with a pile of numbers that I’m tempted to treat as a type of outcome study for lack of anything better to go on. I’ve done my best to identify patterns but in reality I know they are inconclusive.

So far the most attractive logic all too often seems very paradoxical and potentially misleading when it comes to rebreathers. Those wanting to determine risk factors must look deeply below the surface.

For an example of just one instance of the convoluted, anti intuitive state of things, you suggest that the risk of accidents on mCCR will go up as people push them more. That seems very logical but I’d don’t see support for that in outcomes, not so much even for eCCR’s. the number of mCCR divers and the level of challenge of dives performed on them appears to have been going up for some time now and still, no increase in fatalities. And While it seems logical that the more one pushes their unit, the more at risk one would be, but the numbers seem to suggest a counter force in trends. As is the case in so many aspects of rebreather diving there is a surprising twist that seems to turn the equation on it’s head… from what I can see many of the accidents occur on relatively routine dives by relatively experienced divers (and on eCCR’s nearly exclusively), not in the envelope pushing zone or much by beginners either. Some even happen in swimming pools. I would suggest that the more challenging a dive is perceived to be, the more attention gripping it is, and that could be leading to the added risks being overcompensated for by the added vigilance (before and during the dive)…conversely lowering the fatality rate on more demanding dives.

To extrapolate further, it would seem more logical that as mCCR’s are used in more envelope pushing dives that the risk of fatality goes down even further, not up, on such dives since they inspire greater vigilance all the more. Inspiring vigilance on a routine dive is harder to build into the system of an eCCR where a diver tends to be more relaxed. Relatively routine dives are where the fatalities seem to happen most and where I believe being forced to remain vigilant will save lives more effectively than trying to remind ones self to remain vigilant when there is not a consistent need. If there is a better way of achieving that than manual injection than I’m all ears.

g

Very interesting set of arguments. As mentioned, impartiality & time would give us a better look at these niches of CCR diving & the establishment of trends. I can only speak for myself...in those dives where task loading, and "s__t" hits the fan scenarios occur it's advantageous (in my book) to have a parachute. This parachute would be a autonomous system firing a solenoid.

While highly developed MCCR skills may act as preventative measures overall, diving is a "live" activity and no one can ever determine an outcome in the water. I've been lucky in over 30 years of diving hard, to come out mostly unscathed. However, there are times when accidents will occur, no matter what you do. I know this very, very well. Also, as an instructor, I never take risks where my student well being is paramount. Even with vetting, lots of training and supervision - things happen, and when they do...Holy Enchilada! Backups, contingency plans are crucial for a best outcomes. In all, it all points again to selection, education, not pushing the edge and development of a systematic method of keeping that PO2 at life sustaining levels. Most, incidences will relate to the afore mentioned categories.

That being said, in dives where that "boom" scenario looms, I do like to have the option of somewhat "autonomous" monitoring, with injection. There have been a few instances where active monitoring and injection have been really useful. Rescuing someone, when stuff collapses on you, or getting trapped are a few of the scenarios I've lived through with the ECCR. I am happy to say that the ECCR's that I was using took away some responsibility of manual injection and monitoring during times of extreme duress. Very thankful for it. My worst scenario came deep inside a wreck, buddy gone and in zero viz.

As you've mentioned, some incidents have happened in pools. This is always perplexing to me; an ugly phenomenon likely attributable to lax preparation and zero monitoring by someone . Sadly, I have been directly, or peripherally involved with some of the individuals who have had difficulties in pools. If anything, both were sloppy and egotistical. Never a good combination. In fact, it points specifically to the learning domain that controls MCCR, or ECCR operations - ATTITUDE.

In all, it's an interesting conversation and the areas of this discussion/debate will yield results over time. In the meantime, I will continue to fly my kit manually 85% (ECCR) - (MCCR) with all my units.

Good diving

X

p.s. about the doggie...I don't really know what occurred behind the scenes, but I would imagine that there was a high level of human monitoring for all the critters under anaesthesia. I can't see how it could be mechanical...given the high degree of variability and tolerance to gases. However, it is an interesting supportive corollary to this discussion. Additionally, I'll have to check your conversations on that "flame-fest" called RB world. It has to be interesting!

 

[Gill Envy]

In all, it's an interesting conversation and the areas of this discussion/debate will yield results over time.
X

Indeed, and the clock is ticking and the fatality ratio between m+eCCR's is only further diverging even though the number of mCCR's is exponentially increasing. How long do you think the industry should wait till drawing an actionable conclusion or even taking the apparent difference seriously? My fear is that unwitting consumer demand and profit minded manufacturers are driving the market for eCCR's, not science.

 

[TSandM]

Going back to the original post in this thread, people who found it interesting might also enjoy reading Underwater Journal #6. They did short essays on about 20 different rebreathers that were featured at DEMA. Although I know next to nothing about the units and am not in the market for one, I still found the articles quite interesting and educational reading.

 

[Mr.X]

Going back to the original post in this thread, people who found it interesting might also enjoy reading Underwater Journal #6. They did short essays on about 20 different rebreathers that were featured at DEMA. Although I know next to nothing about the units and am not in the market for one, I still found the articles quite interesting and educational reading.

Thanks for posting that. It's very interesting (for me) to see the variety that is now offered. Having written and produced some early documents related to CCR diving, it's just terrific to see the range available to everyone, not to mention the creative paint schemes & wealth of written resources.

As stated in the article, the offerings (a mere ten years ago) were limited to the CIS Lunar, MK's and some early Inspirations. At 15,000 and a year long wait for the CIS, RB's are now so readily available that a mouse click will do ya.' Ten years makes quite a difference., and thank heaven for that.

X