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Thread: Deep Stops (rebreather dive charts)

  1. #251
    RebreatherWorld Sponsor rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh's Avatar
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    Re: Deep Stops (rebreather dive charts)

    Quote Originally Posted by djd  View Original Post
    The A2 (deep stops) schedule was produced by the BVM(3) bubble model, and resulted in an observed DCS incidence consistent with the bubble model prediction.



    And yet the profiles resulted in 13 cases of DCS (and not thermal injuries).

    David Doolette
    Your BVM(3) model is unique and is NOT represent a VPM-B model. They are very different and you confirmed this.

    The ZHL, VPM-B and NMRI(98) models, all predicted the nedu result correctly - for both A1 and A2 profiles. Only the BVM(3) failed to predict correctly - it was completely wrong on the direction of risk - it failed. We don't care about the failed BVM(3) out here, and I wish people would stop trying to pretend that nedu testing represents the tech models we use here today - they do not.

    All dive pressure injuries fall under the DCS umbrella - including those from thermal stress origins.

    The injuries from both the A1 and A2 profiles came from high thermal stress basis (the desired nedu test method). The diver subject results showed susceptibility to the randomness of thermal issues.

    The injuries do not represent those from the traditional high gas pressure stress that is the normal type diving risk. The gas analysis has little relevance, as it fails to show the randomness of thermal stress that caused the injuries.

    .

  2. #252
    RebreatherWorld Sponsor rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh is just really nice rossh's Avatar
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    Re: Deep Stops (rebreather dive charts)

    Quote Originally Posted by UWSojourner  View Original Post
    For reference, I've reposted the basis for the claim below. All four deco methods shown in the chart have identical run times.

    Your denial of the usefulness of supersaturation-time as an important decompression metric is odd. Time spent in a supersaturated state seems so universally accepted as an indicator, or index, of decompression stress or bubble formation potential. It seems worthy to me to consider it in evaluating profiles of the same run time. Dr. Doolette's post here dealt with the issue, but if you read the NEDU report you'll see these concepts everywhere (as well as in VPM as Dr. Mitchell pointed out in his last post).

    So, the basis of the claim is simple math. At the surface, the time exposure to supersaturation (i.e. integral supersaturation) for VPM-B+4 is 555.1k mb-min. For the exact same dive and for the exact same run time, GF 40/74 has a time exposure to supersaturation at the surface of 423.8k mb-min. VPM's deep stops allow continued on gassing in the slower compartments that result in exposing the diver to about 31% higher supersaturation stress at the surface when those slower compartments are off gassing. That's the basis of the statement. I'll leave it to others to decide for themselves the merit.

    Diving risk is far more complex that your simple mb-mins. If it was that simple, then we would not need decompression models.


    The mb-mins is not validated, calibrated, defined, or recognized as any kind of stress measure in diving. Its just a made up number, without any worthwhile relevance. It cannot distinguish between high stress conditions or harmless residual off gassing, or any other aspect.

    As I showed before, a 10 hour flight, a 2 day trip to a ski mountain, or a car trip to Calgary, has a higher mb-mins than the dive example.

    Which makes your stress graphs just meaningless nonsense - eye candy. You keep posting these over - like it's an advertising or a PR effort.


    .
    Last edited by rossh; 17th February 2014 at 20:11. Reason: removed personal attack

  3. #253
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    Re: Deep Stops (rebreather dive charts)

    Quote Originally Posted by Simon Mitchell  View Original Post
    Addressed here:


    __________________________________________________ ______________



    And how on earth would you know this??? You have no outcome data for VPM-controlled dives. The pattern of late slow-tissue supersaturation favored by VPM (Kevin's analysis) and shown to be disadvantageous in the NEDU study may be hurting way more people than you think.
    __________________________________________________ ______________



    An analysis of mb-mins is the only plausible explanation for the NEDU study outcomes. And there is the minor technical detail that integral supersaturation is a fundamental component of the VPM model.
    __________________________________________________ ____________



    Addresssed here:


    The link post you refer, that contains your summation of my criticism and the faults I find of the nedu test, explanations and conclusions - is not accurate.

    The contrived answers you provided do not address the faults correctly.

    You keep referring too your own expert answers in that post. But it amounts to nothing more than you quoting yourself - Self-citing.

    .

  4. #254

    Re: Deep Stops (rebreather dive charts)

    Well, to say we're rehashing the same thing would be an understatement. I had really not meant to retry the NEDU study here. This thread was meant to consider a real CCR dive using some of the same metrics that were discussed in the NEDU deep stop thread. I think we've done that.

    As a summary I'll direct future readers to the following:

    1. Heat map and integral supersaturation for CCR 270ft 20min dive can be found here.

    2. Peak gradient factors and integral supersaturation by compartment can be found here.

    That was the primary data for the CCR dive that was the topic of the thread.

    Many seemed to like the discussion and pull some good things from the topic, including a very helpful post by Bruce here. The clear dissenter on all topics and ideas discussed was Ross. I'll leave it to others to decide motive or merit of any of his posts.

    Thanks to Dr. Mitchell and Dr. Doolette for participating.

  5. #255
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Deep Stops (rebreather dive charts)

    OK Guys, thanks to all for coming out. It's been a blast but I really think we're done here. I learned a lot.
    Cheers,

    Dave....

    www.wedivebc.com

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