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Rob Stewart Investigation

Discussion in 'Apps, Book and Media Reviews' started by Rosborne, May 14, 2020.

  1. wedivebc

    wedivebc CCR Instructor ScubaBoard Supporter

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    Why would someone switch off a functioning rebreather to a bailout gas?
     
  2. Rosborne

    Rosborne Nassau Grouper

    # of Dives: 500 - 999
    Location: Canada
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    All very relevant questions.
     
  3. wedivebc

    wedivebc CCR Instructor ScubaBoard Supporter

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    How do you even blend 10/20?
     
  4. Protondecay123

    Protondecay123 ScubaBoard Supporter ScubaBoard Supporter

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  5. KenGordon

    KenGordon Rebreather Pilot

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    The SI of 25 minutes between the second and third dives looks to me to drop them in with considerable bubbling going on. They’d all be squashed to get past the lungs and distribute them throughout the arterial system.

    They did several things that increase the likelihood of a bend. High GF (more than 90 due to the lying to the computer about the helium - that alone would be an extra 10 minutes of stops), very fast ascent to the (relatively shallow) first stop, three long deco dives in a day, and that extremely short SI before the final bounce.

    Given nothing else that was clearly the cause (bad gas, broken kit, hit by a boat etc) it seems to me that they were bent.

    My normal settings (50/80) would have given me another half an hour (so 85 minutes rather than 55) of deco/ascent time.
     
    Rosborne and Protondecay123 like this.
  6. Tassi Devil Diver

    Tassi Devil Diver Barracuda

    # of Dives: 1,000 - 2,499
    Location: Tasmania, Australia
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    If I did the first dive according to my usual parameters 70m for 35min with TX 15/60 (I don't lie to my computer) and GF 50/80 my run time will be 142min a whopping 50min more deco!!
     
    shoredivr and Protondecay123 like this.
  7. KenGordon

    KenGordon Rebreather Pilot

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    I assumed 65m rather than 70 as they didn’t spend long at max depth. I mostly did it to see how the helium lies changed the runtime.
     
  8. Protondecay123

    Protondecay123 ScubaBoard Supporter ScubaBoard Supporter

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    Do you know the content of Oxygen? I'm thinking his CNS O2 may have been much greater than the computer calculated.
     
  9. KenGordon

    KenGordon Rebreather Pilot

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    The computer was measuring ppO2 so the CNS numbers ought to have been ok. In any case people get away with taking much worse liberties with O2 exposure that they do shortening deco.
     
  10. Protondecay123

    Protondecay123 ScubaBoard Supporter ScubaBoard Supporter

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    Well Ken, I was looking at their mix and they had 10/20 entered which I figured was a little on the hypoxic side for 218 fsw. Rob says that the Helium content was actually 50% not 20%. So I thought that maybe the Oxygen content was more like 18% or 15%? Which should push up the CNSO2
     

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