Still Thinking about Rebreathers?

This is some very weird logic. The manual approach no more compels good habits than anything else and likening the risks of open circuit negligence and rebreather negligence is clearly flawed. Under the right conditions I can dive open circuit and never once glance at my gauges. I shouldn't do so but I won't die if it happens.

 

I'm following this thread with interest, but I find the argument that manual CCR forces good habits and is therefore superior to be akin to claiming that doing away with all traffic lights and stop lights improves traffic safety. It does not, of course, what it does is slow traffic to a crawl. The same effect could be had by outlawing cars. Doing away with rebreathers will "improve" their safety, too, but not in the way people want. A true improvement would be to make a system that really works better, not one that strips functionality to a minimum.

>>Under the right conditions I can dive open circuit and never once glance at my gauges. I shouldn't do so but I won't die if it happens.

OC divers die all the time when they make the basic error of not checking their gas supply.

>>I'm following this thread with interest, but I find the argument that manual CCR forces good habits and is therefore superior to be akin to claiming that doing away with all traffic lights and stop lights improves traffic safety.

I think that is a false analogy. Traffic lights coordinate the behaviour of a large number of people, which is not at all similar to this case of a single person monitoring their own gauges.

The mCCR argument is that ALL CCR divers need to be careful and monitor their pO2 level. eCCR lets you get away with not doing so as long as everything is working as it should. Given the added failure modes of an eCCR over mCCR this is risky. So if you get complacent then you can get into a very dangerous state where you just black out with no warning. (p02 very low) mCCR's have fewer points of failure (no electronics or solenoid vs an mCCR's constant flow of o2) and you have to monitor your gauges for basic operation. The reality is that you have to do this for both designs but not everyone does. Someone else mentioned a HUD, which you can add to any type of rebreather so I don't see that as a point of difference.

If you are a safety conscious eCCR diver then it is every bit as safe. I still think that mCCR is better for ME because I have witnessed to many electronics problems in the field with Inspo and Evo systems over the last 5 years or so.

What I like about hybrid rEVOs is that you use it on manual (leaky valve plus manual additions) but if PO2 goes down (distraction...) the solenoid it has will kick in automatically as a "parachute". You can also run it in eCCR mode:

http://www.zerogravitydiving.com/Documents...ybrid%20CCR.pdf

As per mCCR/eCCR safety, there have been rivers of ink writen. If I had to choose I would go mCCR as accident studies have found mCCRs are safer than eCCRs with a 250,000:1 level of confidence.

http://www.deeplife.co.uk/or_accident.php

OC divers die all the time when they make the basic error of not checking their gas supply.

No they don't. I don't think OC divers die all the time for any reason, but to the extent they do it's not because of gas monitoring.

OC divers cannot experience hypoxia and, depending on conditions, might not be at risk of oxygen toxicity either. If they are no-deco diving, even an out-of-air condition is managable if they don't panic and there's plenty of warning with modern gear. I may suffer serious injury or death if I make other mistakes like fail to monitor depth, bottom time, deco, ascent rate, etc. but I simply won't die if I fail to monitor my gas supply (subject to conditions that I know up front).

I think that is a false analogy. Traffic lights coordinate the behaviour of a large number of people, which is not at all similar to this case of a single person monitoring their own gauges.

That's not the analogy I'm making. The analogy is that both approaches claim to solve a problem by removing technology that is valuable yet is perceived to be imperfect. I'm simply saying that mCCR is throwing the baby out with the bathwater.

If you are a safety conscious eCCR diver then it is every bit as safe. I still think that mCCR is better for ME because I have witnessed to many electronics problems in the field with Inspo and Evo systems over the last 5 years or so.

I think that's a reasonable position to take. Different people respond differently and may well be better suited to different gear. I won't ride a motorcycle even though I know they can be ridden safely.

With mCCR does your dive computer know the partial pressure of the gas you are breathing?

No they don't. I don't think OC divers die all the time for any reason, but to the extent they do it's not because of gas monitoring.

 

OC divers cannot experience hypoxia and, depending on conditions, might not be at risk of oxygen toxicity either. If they are no-deco diving, even an out-of-air condition is managable if they don't panic and there's plenty of warning with modern gear. I may suffer serious injury or death if I make other mistakes like fail to monitor depth, bottom time, deco, ascent rate, etc. but I simply won't die if I fail to monitor my gas supply (subject to conditions that I know up front).

 

 

That's not the analogy I'm making. The analogy is that both approaches claim to solve a problem by removing technology that is valuable yet is perceived to be imperfect. I'm simply saying that mCCR is throwing the baby out with the bathwater.

 

 

I think that's a reasonable position to take. Different people respond differently and may well be better suited to different gear. I won't ride a motorcycle even though I know they can be ridden safely.

 

With mCCR does your dive computer know the partial pressure of the gas you are breathing?

OOA - Well, I'll have to disagree. People diving OC get OOA and Torpedo to the surface all the time resulting in drowning, embolism, or severe DCS on a regular basis. There are several people just in Seattle that have done this in recent years. Read the DAN reports some time.

Traffic Lights - Maybe a better analogy is your car's speedometer vs cruise control. When you are going straight and level with traffic you may not need to look at your gague very often (mCCR). But when you start going up a hill or into a school zone you probably need to take a look and make adjustments. Does your cruise control (eCCR in this case) know about the unexpected situation of a school zone? No, you need to pay attention and make a manual adjustment. If you are too inattentive to slow down you risk squashing an adorable toddler.

The problems that the accident studies show on eCCRs is that the electronics are crap, software is full of bugs, and the automated O2 / Dil injectors have inadequate redundany for life critical systems. Now there may be much improved systems available now or in the future, but the state of the art has a long way to go.

You can certainly get a dive computer with active loop monitoring that can be used with any mCCR system. There are at least half a dozen choices on the market that have this capability. (Liquid Vision, Shearwater, VRx, etc...)

OOA - Well, I'll have to disagree. People diving OC get OOA and Torpedo to the surface all the time resulting in drowning, embolism, or severe DCS on a regular basis. There are several people just in Seattle that have done this in recent years. Read the DAN reports some time.

I don't consider those to be deaths due to failure to monitor gas supply. There are far more problems than that. I also don't view several over a period of years to be "all the time".

The problems that the accident studies show on eCCRs is that the electronics are crap, software is full of bugs, and the automated O2 / Dil injectors have inadequate redundany for life critical systems. Now there may be much improved systems available now or in the future, but the state of the art has a long way to go.

That's not what you are arguing though. You are claiming that manual is better because it creates a user than is inherently safer in his habits. Not only is this not true for everyone, if there are problems with current automation systems that's not evidence that there shouldn't be automation systems.

You can certainly get a dive computer with active loop monitoring that can be used with any mCCR system. There are at least half a dozen choices on the market that have this capability. (Liquid Vision, Shearwater, VRx, etc...)

But then there are electronics that can fail, right? How does a manual CCR diver eliminate any dependency on electrical systems yet ensure that his computer is always modeling his actual partial pressures? Do you also dive tables to eliminate the possibility of computer error or failure?

It seems to me that there is additional risk in having a computer model that doesn't correspond to actual partial pressures. You either accept that or you expose yourself to electronics failures anyway.

I wonder what people that are afraid of CCR control electronics have against SCR.

But then there are electronics that can fail, right? How does a manual CCR diver eliminate any dependency on electrical systems yet ensure that his computer is always modeling his actual partial pressures? Do you also dive tables to eliminate the possibility of computer error or failure?

Not really an issue as the dive computer does not control anything at all with mCCR. If just provides an accurate readout and realtime dive profile. The diver is still responsible for maintaining a set point, not the electionics. With an eCCR the computer can go HAL 9000 on you start doing crazy things to your gases. With the KISS you typically have 3 redundant passive pO2 montiors, and people often supplelment this with an integrated computer. Personally I just stick with the passive readouts and wear a Cochran wrist comp.

Anyway, there are endless options all with pros and cons. At the end of the day I enjoy being able to do a 90+ minute shore dive, having increased bottom time on a wreck, the silence of CCR, and the ability to sneak up on any fish in the sea. It's added a lot to my diving experience and my understanding of dive physiology.

Dave

Thanks to the American system of litigation there have been plenty of cases tried. Can you point me in the direction of any case where the eCCR was proved to be at fault?

The outstanding popularity of one brand of CCR makes it statistically more likely to be associated with fatalities.

I think divers need all the help they can get if they are being distracted by cameras. Only my opinion.

When I began this post it was to inform Wetpixel members that KISS’s current prices against the American dollar still make the KISS rebtreather – be it the Sport or the Classic the most affordable option. Unlike some models people still waiting on which has neither a tract history or is still in the hypothetical stage of release. My main point is the KISS is here now, readily available, has a trusted, solid reputation, the price, well…

The Sport KISS starts at $4,600, with the Classic going for $5,700 Canadian.

Comparing the Canadian dollar to the US, for $3,842.25 (U.S.) will get you KISS triple PO2 displays. Or if you prefer to get fancy, for $5,204.36 US, would get the same Sport KISS with a VRx computer.

Now I find it funny how it has evolved into this heated debate over which is better ECCR or MCCR.

Craig to your statement “The analogy is that both approaches claim to solve a problem by removing technology that is valuable yet is perceived to be imperfect. I'm simply saying that mCCR is throwing the baby out with the bathwater.” Followed by your question “With mCCR does your dive computer know the partial pressure of the gas you are breathing? Tells me you little to no experience with MCCR’s, with perhaps just as much with Closed-Circuit Diving equipment in general.

Yes, VR Technologies new VRx, the Shearwater Pursuit and Dive Rites recent release of their Nitek X dive computers are designed to interface (through cable link) with the rebreather’s three Oxygen cells. When connected, these computers provide the diver the option of performing basic PO2 monitoring with the computer running its own algorithm at the set-point you have chosen, or in a mode where it both monitors and calculates your current profile based on the information it is receiving from those three cells.

O2 cells have improve quite a bit in they’re reliability over the years but a diligent CCR diver with check the cells calibration before they go diving. Really not much different checking camera’s and strobes battery levels before starting days shoot.

Granted, there are people that come to this forum who are not ready for rebreathers, just a there some that shouldn’t be trusted past a mask and snorkel. Just because some individuals, based on their own experiences, have found rebreathers to be too hard to dive, shouldn’t try to speak for everyone. The equipment is what it is, individuals are who they are, and the degree of instruction and training is usually what helps decide the out come.

If everyone want s to continue this debate, I like to invite you to come over to Rebreatherworld.com and exchange your opinions with a group that knows both systems, like you know DSLR’s.

No-one's heated. Not here at least.

It's jolly nice a KISS is so inexpensive to buy.

Why do you appear to be so partisan? Do you have shares in the company?

I was present when Stuart Ford did a try-dive on a Draeger on mv.Hurricane in the Red Sea. He went away and started RBW. It wasn't very long ago. (I originally did some development work for Draeger but I never really saw the advantage in an SCR) I did my original rebreather try-dive with Peter Readey in 1992 also in the Red Sea. I had hair then.

Now let's discuss whether it's better to have manual or auto focussing...

This is not a heated debate, at least not to me, it's an interesting discussion. Don't interpret any challenge I make as advocacy of anything. I'm merely playing devil's advocate to the pro-MCCR points here.

Craig to your statement “The analogy is that both approaches claim to solve a problem by removing technology that is valuable yet is perceived to be imperfect. I'm simply saying that mCCR is throwing the baby out with the bathwater.” Followed by your question “With mCCR does your dive computer know the partial pressure of the gas you are breathing? Tells me you little to no experience with MCCR’s, with perhaps just as much with Closed-Circuit Diving equipment in general.

Yes, I have no experience with CCR. As for that first statement, is it wrong? The purpose of my question was to lead to the following:

Not really an issue as the dive computer does not control anything at all with mCCR. If just provides an accurate readout and realtime dive profile. The diver is still responsible for maintaining a set point, not the electionics.

The computer is life support equipment even if it doesn't control anything in the CCR. In OC and SCR, the mix and depth determines partial pressures but in CCR they deliberately vary. There is a potential for problems when there is a difference between what you breathe and what the computer thinks you breathe. MCCR doesn't eliminate exposure to electronics, it either reduces them or trades them for other risks.

I'd like to understand why someone who feels strongly against ECCR because of risk and complexity, and who advocates MCCR instead, doesn't consider SCR as an alternative. I have had some experience with SCR. I agree with John that photography takes too much of my attention to devote myself to constant monitoring to solve a problem that should be solved with automation.

Here's another analogy. Imagine for a moment that someone believed that the pressure sensor in a dive computer posed and unacceptable failure risk and implemented a computer, instead, that required the diver to frequently enter current depth manually. It is inarguable that this new computer would have one less mode of failure, but is it more safe as a result? Does the mandatory user input force the diver into safer diving habits? I think the clear answer to both those questions is no, yet the logic involved is identical to that being used in support of MCCR superiority here.

Why do you appear to be so partisan? Do you have shares in the company? smile.gif[/quote}]

 

While I admit this thread stinks of commercial bias, I have to say rebreather owners are some of the most partisan people I've met.

 

I applaud the companies that are developing automated systems that have the potential of making CCR diving safer. CCRB, Deep Life, and CIS Lunar are certainly leading this charge.

 

I dive a Hybrid rEvo. If an electronics package becomes available that can more effectively monitor the loop than I can, validate what I'm breathing, and detect when my cells fail reliably I'll buy it.