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CCR Selection priorities

Discussion in 'Rebreather Diving' started by kierentec, Sep 29, 2020.

  1. kensuf

    kensuf Cave Instructor

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    Why would anyone only open a valve partway? It's not 1975 man, open the valves all the way and quit that quarter turn bs.
     
    NothingClever and evandroairton like this.
  2. Heat Miser

    Heat Miser DIR Practitioner

    # of Dives: 100 - 199
    Location: Perth
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    Honestly I'm a newb asking is this a real problem?

    I have only trained on rEvo > 3 turns only... learning lot's from this thread though ... didn't understand helium leakage. Although why wouldn't you disassemble tanks after a dive?

    Still keen to learn.
     
  3. CptTightPants21

    CptTightPants21 Solo Diver

    # of Dives: 200 - 499
    Location: NY/NC/FL
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    Ken has some photos from a previous thread

    Just ordered my FATHOM!


    Golem Gear, Inc. - LOLA Universal DIN Valve
     
  4. rddvet

    rddvet DIR Practitioner

    # of Dives: 50 - 99
    Location: Florida
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    They definitely roll off very easily. I'm not a fan of that for sure.

    That's kind of my issue. I go back and forth from bm to sm to ccr, then ccr with 3L and 50s. The lola's are the funkiest valves I own, so my muscle memory from other valves doesn't necessarily transfer over and makes me extra cautious since I don't dive the lola valves very regularly at all.
     
  5. sea_ledford

    sea_ledford Captain

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    Completely agree. I haven't taught that way since 1997? Still happens though! I've had probably a dozen people swim up to me at 40 feet freaking out about their SPG doing the windshield wiper.

    Amazingly, yes. Generally at the recreational level, but there have been plenty of fatalities on CCR due to O2 not turned on. And probably some due to no having the dil on and losing suit inflate/ breathing volume on descent.


    Makes sense if you are a hard overhead diver. What does "rotate toward the right post" mean? Is the side of the handwheel closest to your head going toward the right post? Or is it the back of the handwheel that goes toward the right post? And what if I'm dyslexic and get left and right mixed up, especially under stress? If you are unsure of which direction the isolator is supposed to go, how do you check it?

    And how is any of that easier than something like this?
    Screen Shot 2020-10-08 at 1.22.07 PM.png
    I know, I know... line trap. not perfect

    Right, you just have to do it right to make sure you don't do it wrong.

    Human Factors and Ergonomics: Looking Back to Look Forward

    During the second world war, the United States lost hundreds of planes in accidents that were deemed ‘pilot error’. Crash landings were a particular problem for the Boeing B-17 ‘Flying Fortress’. The planes were functioning as designed, and the pilots were highly trained, but made basic errors. In 1942, a young psychology graduate, Alphonse Chapanis joined the Army Air Force Aero Medical Lab as their first psychologist. Chapanis noticed that the flaps and landing gear had identical switches that were co-located and were operated in sequence. In the high-workload period of landing, pilots frequently retracted the gear instead of the flaps. This hardly ever occurred to pilots of other aircraft types. Chapanis fixed a small rubber wheel to the landing gear lever and a small wedge-shape to the flap lever. This kind of ‘pilot error’ almost completely disappeared.
     
    stuartv likes this.
  6. sea_ledford

    sea_ledford Captain

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    Oh, and thanks for proving my point about the public shaming. :)
     
  7. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: Alabama
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    I'm not sure what this is supposed to mean.

    But as to the rest, it comes down to practice. That's why valve drills are part of any intro to tech or fundamentals course. You get used to the way valves turn and where on and off are located. It becomes second nature to confirm position.

    Regarding isolators, it seems kinda self explanatory to me. If I told you to turn a doorknob to the right to open, you wouldn't get confused because the bottom of the knob moves left...
     
    NothingClever likes this.
  8. sea_ledford

    sea_ledford Captain

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    It was supposed to be a bit tongue-in-cheek. Sorry.

    But yes, it does come down to practice and learning how to do it correctly. That is my fundamental issue with it. I probably spend 10-15 minutes on land running though how to do a valve drill, then another 10-15 minutes in water the first time out (depending on the number of students) while they are learning how to do the drill and figuring out how they need to contort themselves to reach the isolator. Then I spend probably 5 minutes of every training dive doing valve drills.

    So in an AN/DP class that is about an hour of training time just learning how to turn their gas on and off! Probably more time than any other single skill. There are a lot of examples of an equipment solution to a training problem, this is one of the few situations of a training solution to an equipment problem.

    Taking your door knob example, turning the door knob to the right is turning it clockwise. But if you are saying "turn your isolator toward the right post to turn it on" that is turning it counterclockwise. So directions of "to the right" while rotating a round thing is only relative to your point of observation. This is why there is port and starboard, and why gas and plumbing valves have direction indicating valves.

    If anyone knows a solid way to teach valve directions to new doubles divers, I'm all ears. All the ways I have heard are dependent on the students having the same spatial orientation as the instructor. I had one instructor that used "Fingers and thumbs" which never made sense to me. Turn toward fingers on one side and thumbs for the other? That doesn't help, how am I supposed to remember which one is which? I'm left with "do it a bunch of times, you'll figure it out." Which is lame.
     
  9. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: Alabama
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    I dunno, sometimes do it a bunch of times until it feels normal is fine. That's how I teach my students to hover. I can throw little tricks in here and there, but ultimately, they just need to do it until they can do it on their own. Valves aren't overly complicated, they just require the right muscle memory to be developed.
     
    NothingClever, grantctobin and PfcAJ like this.
  10. Brad_Horn

    Brad_Horn ScubaBoard Business Sponsor ScubaBoard Business Sponsor

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    There's a readily implemented engineered solution for resolving that risk Open Safety Equipment Ltd
     

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