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Thread: Are mCCR's safer than eCCR's?

  1. #41
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by chrismc  View Original Post
    This isnt quite true, just for constant flow, and therefore unbalanced 1st stages. Variable units e.g. Pelagian do not have this restrcition, others will likely do similar.
    Or....people add another source of O2 (not by leaky valve but completely manual instead) which adds complexity so these guys dive deeper and even then 'fail to die' ? I think it is yet another clue (and no more than that) pointing towards the diver being a very important element in the diver/rb combo.

  2. #42
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by cramerdn  View Original Post
    Cool, 100 more accident free hours on my unit and I ought to be stupid enough to make similar comments.

    The diver is the majoriy of the issue in any accident. There are plently of human factors in accidents other than just "human error". Rebreathers are certainly less forgiving than OC but its the divers that are more safe or less safe.

    So the question really should not be what type of unit is safer but what type of diver is safer.
    From reading this i deduce you have no experiance diving a MCCR?

    Ill try and phrase the point another way for you.

    What has diving an inspo taught you about 02 consumption on critical phases of the dive?

    How does the Inspo go about reminding you over and over again about such critical points?


    In the 400+odd hours I had on the inspo it taught me bugger all.


    On a kiss you look down at the hand set and its says 0.6ppo2 and you think s#it s#it s#it I wasent paying attention again. You find some spidge and bag it up and check your hand set and think s#it s#it s#it that took longer than i thaught and used more 02 than i thaught.

    It constantly reminds you how incompitent you are and sets chalanges for you to imporve and do better next time. It forces you to be mentaly in tune with the unit and its performance. It forces you to be aware of everything.

    A ECCR does nothing it just says 1.3 1.3 1.3

    It does this for hundreds of hours quietly lulling you into a false sense of security. Till in the end you just don't bother worrying about it any more.


    Then it kills you.

    I have seen ECCR divers eyes glued to their hand sets in the early days and then a couple of years later thay hardly ever check them during a dive.

    This fact has sadly been proven over and over again in the reports covering the deaths of ECCR divers.

    The fact that MCCR's force their owners to be on their game at all times has also been proven by the lack of MCCR fatalities.


    ATB

    Mark

  3. #43
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    Re: Are mCCR's safer than eCCR's?

    I think Marks post summs up most of the reason behind my line of thought.

    On an eCCR you dont have to monitor things, it does it for you. You check, its still 1.3 etc. you become complacent. Somehting goes wrong, you hope you pick it up and remember.

    On a mCCR, you have to check, act, review and repeat. You learn to be responsible for the unit yourself. When it goes wrong its just an extension of a cycle you have repeated countless times. I dont think you can get this experaince unless you have done it.

  4. #44
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by chrismc  View Original Post
    I think Marks post summs up most of the reason behind my line of thought.

    On an eCCR you dont have to monitor things, it does it for you. You check, its still 1.3 etc. you become complacent. Somehting goes wrong, you hope you pick it up and remember.

    On a mCCR, you have to check, act, review and repeat. You learn to be responsible for the unit yourself. When it goes wrong its just an extension of a cycle you have repeated countless times. I dont think you can get this experaince unless you have done it.
    For me, there's one critical difference that isn't mentioned often, if at all. Distraction on an eCCR won't kill you unless it happens at a time that the unit happens to have packed up, regardless of how long you are distracted. Frankly, on most current units, that's a statistical risk.

    Distraction on an mCCR will kill you if you leave it long enough (and at critical phases of the dive, that may not be long). Regardless of what you do, that's a real risk.

    I've read a few posts about people nearly going hypoxic on or near the surface on mCCR units, apparently through distraction. I'd also be concerned about the same thing happening in an emergency where you are helping others, such as a CBL.

    I'm absolutely sold on the idea that mCCRs sharpen your wits (though I don't accept the apparent corollary that the opposite is necessarily true for eCCR , but the real distraction (vs complacency) risk is one that put me off mCCR.

    A small point - if I'm wrong, I'm sure everyone will tell me.

    Cheers,

  5. #45
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by andrespp  View Original Post
    First, think that probably there is no basis to say that a mccr is safer than an eccr from the statistical point of view, as there are far more of eccr than mccr. My Ckiss bought two months ago is serial nr. 332, and it is my understanding that AP has sold at least 10.000 units of its models.
    Uhmm, time to butt in here:

    What AD and others have collected data for shows:
    Is the fatality rate on eCCR higher than the fatality rate on mCCR for perdive-year?
    Answer: Yes
    Confidence: 1000:1

    This means that even when taking the low no of mCCR units into account, AND the low no of fatalities occured on mCCR the chance of the answer being wrong is 1:1000!

    Statistics are a tool, but you have to read the question, and understand the confidence - It does not correct for:

    * The very high incedence on the early Classic YBOD, so one could argue that this skews the result, compared with todays CCRs. Theres no published results without the Classic.

    * It does not include Needle-valve mCCR, only the KISS-types.

    * It does not say that the mCCR are x2-times or x100-times safer. Ie. it does not quantify how much safer mCCRs are, only that they *are* safer. It would however be an interesting question if its say x10 or better....

    * It does not tell us why they are safer, only that they are.....

    So to answer the OP: Yes
    Reason: See all the post in the thread

    Nicolai

  6. #46
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by PhilSiswick  View Original Post
    ...
    I've read a few posts about people nearly going hypoxic on or near the surface on mCCR units, apparently through distraction. I'd also be concerned about the same thing happening in an emergency where you are helping others, such as a CBL.

    I'm absolutely sold on the idea that mCCRs sharpen your wits (though I don't accept the apparent corollary that the opposite is necessarily true for eCCR , but the real distraction (vs complacency) risk is one that put me off mCCR.
    ...

    In that case isn't the real question whether the risks of distraction is more dangerous than the risks of complacency. It is really the same issue, just stated a little differently. What would the best available accident information suggest on that question?


    Sincerely,

    -paul
    Last edited by PaulTG2; 18th August 2008 at 18:53.
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  7. #47
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by PhilSiswick  View Original Post
    I'm absolutely sold on the idea that mCCRs sharpen your wits (though I don't accept the apparent corollary that the opposite is necessarily true for eCCR , but the real distraction (vs complacency) risk is one that put me off mCCR.
    Phil makes a good point and he made another when we discussed this previously (but not on here) which I think bears repeating.

    Numerous "MCCR is safer than ECCR" debates are fueled by ECCR diver who've not dived an MCCR (turning your setpoint down and running manually doesn't count) and MCCR divers who've not dived ECCR's...

    An ECCR probably can't visualize the sublte rise and fall of PPO2 and the coresponding adjustments in depth, workrate and manual injections the same way a Leaky valve diver might, by the same token an MCCR diver won't understand the fun and games ECCR diver play with their solenoids an ascents and descents (for a rough example of somewhere the two systems differ strongly)

    Hence why posts by people like Chasey who've experience of both should carry weight IMO.

    Better, Worse? or just Different.... its not a competition ;)

  8. #48
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    Re: Are mCCR's safer than eCCR's?

    I cannot speak for anyone else diving an eccr, but I can speak from my personal experience.

    I hate to dissappoint you nay sayers and put a hole in your theory, but an eccr diver is quite capable of developing the same consitent monitoring habits, as an mccr diver - I know, because I have!

    Just as you have to inject your O2 manually, I instead chose to frequently and regularly monitor my primary handset, my HUD and my 4th cell connected VR3.

    I know, I know - Us lazy and undisciplined eccr divers are incapable of chewing gum and walking at the same time, because we opted to go with an eccr instead of an mccr, and we're all going to kill ourselves, but I respectfully disagree.

    And as far as not being capable of understanding how our O2/PO2 is affected at critical points of the dive - Sorry to again dissappoint you, but our small minds can understand that as well, as it's too difficult to figure out why our PO2 is dropping much faster and our selenoid is firing much faster. As for myself, I know you think it's not possible, but I do monitor my PO2 much more frequently than usual at those critical times - Sorry again!

    The bottom line is, that each diver needs to make the personal decision whether he/she feels as though he/she has the self-discipline required to monitor his/her rebreather with the diligence and frequencly needed to dive it safely. If not, than they should go with an mccr, or perhaps go back to open-circuit.

    If you feel you do not possess the self-discipline required, and subsequently made the personal decision to dive an mccr instead, that's great, and I applaud you for making a wise decision, but don't now point the finger at others who feel as though they do possess the self-discipline needed to do it safely.

    Sure I know, blah, blah, blah, now you're going to again repeat that the statistics prove otherwise, and tell me all about the divers who have had problems on a eccr, but those divers perhaps didn't possess the ability to make the correct decision and got themselves into trouble because of their lack of adequate self-analysis, but I suspect those very same divers might of probably gotten themselves into trouble on an mccr, because a lack of self-analysis will always get you into trouble. Perhaps those divers had no business diving a rebreather at all, mccr or eccr? Perhaps that's a training issue due to instructors not evauating the self-disciplinary habits of their students? Or perhaps Darwin's Theory holds true and they didn't survive? I'm not trying to belittle anyone who unfortunately lost their life diving a rebreather, but I'm also not going to play mom & dad and tell someone what they should do and what kind of unit they should dive - Again, personal choice, and each of us should be prepared to live with the consequences of our decision!

    And btw, even though I dive an eccr, yesterday, I dove an entire dive on mccr mode, while taking pictures with a pretty large camera and dual strobes, fighting the current and towing a reel with a float ball attached at the surface, and let me assure you, it's an over-rated experience; consequently, just as I traded in my bicycle for a BMW, I'm going back to eccr mode, because I'd rather monitor closely, than have to monitor and use a free hand to inject!

  9. #49
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by PhilSiswick  View Original Post
    Distraction on an mCCR will kill you if you leave it long enough (and at critical phases of the dive, that may not be long). Regardless of what you do, that's a real risk.
    True if you leave it long enough. My own two scares where it concearned two lows (although not critically low) were when just browsing for fish near the surface, in other words when dead calm. If the orifice had clogged that moment the outcome might have been determined by my buddy only . However when really busy it is more important than anything else.
    I had two uncontrolled ascents when learning to dive my drysuit. On both occasions I injected like crazy. That's the funny thing about mCCR it teaches you to be razor sharp when you are busy. Checking the hand set is both event driven (check when you have ascended/decended a bit or swam hard) and time driven. The latter one is needed when your dive is litterally uneventfull. I find the latter one harder but the mCCR allows for many minutes of breathable gas in such a case (UNLESS of course your orifice blocks)...
    I hope that makes sense...

  10. #50
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    Re: Are mCCR's safer than eCCR's?

    Quote Originally Posted by sfldiver  View Original Post
    IAnd btw, even though I dive an eccr, yesterday, I dove an entire dive on mccr mode, while taking pictures with a pretty large camera and dual strobes, fighting the current and towing a reel with a float ball attached at the surface, and let me assure you, it's an over-rated experience; consequently, just as I traded in my bicycle for a BMW, I'm going back to eccr mode, because I'd rather monitor closely, than have to monitor and use a free hand to inject!
    Define "MCCR mode"? As far as I know the stock optima doesn't have a leaky or needle valve O2 add system... so you where not diving as most MCCR divers dive- you where diving a "simulated broken ECCR" which is a different beast entirely.

    Under the situation you suggested a Needle valves MCCR diver might up his O2 flow rate, a Leaky valve diver might lay on the MAV for longer and go up to 1.4 or so to allow for the workrate increase and allow a longer drop before adding more O2 thus maintaining a reasonable average with similar manual interventions.... and I would dare to suggest an ECCR diver playing at manual injections might be tempted to use his rebreather as intended and enjoy the dive rather than pretend its something its not!

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