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Wishlist: how can rebreathers be improved to make them even safer ?

Discussion in 'Rebreather Diving' started by Roger Hobden, Sep 2, 2018.

  1. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
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    Great post, that answers many questions that I had !

    Thanks a million !
     
    Fibonacci likes this.
  2. Wookie

    Wookie Secret Field Agent ScubaBoard Business Sponsor

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    You know, you ask questions that have been asked here a thousand times, and a little research would keep you from asking them again. Then someone comes along and answers your questions, but you don't like their answers, you want answers to a different question.

    A little advice I like to give to new members is to watch the interactions here. Do some searching. See if someone has already asked the question, and see if the answers are still valid. See if the answers are valid for your purpose. Then, come up with a well thought out question that gets to the root of what you want to know, instead of having to come up with 2 polls because you didn;t get the answers to the first one that you wanted. Or rejecting a well respected member's well thought answer because your question was not as well thought out.

    We all like to see enthusiastic new members, and of course, you are welcome to come here and ask the same questions that have been asked and answered before, ad nauseam. But sometimes it is better to look and listen first.....
     
    rjack321, ajtoady, sunnyboy and 2 others like this.
  3. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    "Rechargeable" CO2 absorbent in a fixed matrix and didn't fail or turn costic when exposed to saltwater -- no channeling, packing, or buckets.
     
    _Slacker_, MichaelMc and northernone like this.
  4. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
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    Point taken.

    I am a teacher in my own area of occupation. I find that one of the common "problems" in many fields of knowledge, is that beginners often don't know which and how to frame pertinent questions in the first place.

    Thank you for all of your comments, though.

    I will keep them firmly in mind.
     
    RainPilot likes this.
  5. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
    376
    111
    43
  6. Wookie

    Wookie Secret Field Agent ScubaBoard Business Sponsor

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    No one is right, or wrong. Or in authority. Well, Pete owns the board, and his rule is “be kind to each other, and if you can’t be kind, at least don’t be a dick”. But the answer is that scuba diving is anarchy. Then when you die we all point our fingers and say “it was the split fins and spare air. We told him not to do that” regardless of the thousands of successful dives made every day with split fins and spare air.
     
    TTPaws, rjack321, muzikbiz22 and 2 others like this.
  7. Roger Hobden

    Roger Hobden Barracuda

    # of Dives: 50 - 99
    Location: Montreal
    376
    111
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    OK, thanks again . :)
     
  8. lv2dive

    lv2dive Formerly known as KatePNAtl Staff Member

    # of Dives: I'm a Fish!
    Location: Lake City, FL
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    I read hundreds of posts before I even created a ScubaBoard account. There is a wealth of knowledge here and after reading dozens of threads, it’s easier to get a feel for the pontificators vs the people who know what they are taking about.

     
    elgoog, RainPilot, joshk and 2 others like this.
  9. KevinNM

    KevinNM DIR Practitioner

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    It’s just a matter of time if you do that. Unless you can back kick in the split fins, then it’s Ok. :)
     
    rjack321, StefinSB and Wookie like this.
  10. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
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    A couple thoughts...

    First let me also stress that you are not a rebreather diver, and thus might be missing some of the subtle nuances that are involved.

    Second, Fock based this statement on some very broad generalizations:

    "With the caveat that they are “best guess numbers,” Fock concluded that rebreather diving is likely five to 10 times as risky as open circuit scuba diving, accounting for about four to five deaths per 100,000 dives, compared to about 0.4 to 0.5 deaths per 100,000 dives for open circuit scuba. This makes rebreather diving more risky than sky diving at .99/100k, but far less risky than base-jumping at 43 deaths/100k."

    Beyond "best guessing" Fock also makes the assumption that all OC diving carries equal risk. That is not the case. As a result to get accurate numbers you have to parse the OC data to get a subset that translates well to CCR use, which for the most part is still strongly biased in the technical and cave diving end of the spectrum. Then within technical and cave diving you have to look at the risks in various types of dives. 300' deep dives are dangerous in both CCR and OC, as are dives with extreme linear penetration . The risks can be different, but depending on the dive OC can be more or less safe than CCR.

    Interestingly Fock identified 43 deaths per 100,000 base jumps. What isn't mentioned is that the accident rate per 100,000 people per year is a nearly identical 42.7 per 100,000 people. In other words, just surviving a year is statistically as dangerous as making 1 base jump per year.

    Let's also quantify 4 or 5 deaths per 100,000 CCR dives. Few divers, OC, SCR, or CCR, have 5,000 dives period. But lets assume a diver has 5000 dives and that ALL of them are SCR or CCR dives. That carries just 1/20th the risk 100,000 dives and similarly the "4 to 5" deaths per 100,000 dives, equates to a .20 to .25 probability of dying in the course of 5,000 rebreather dives.

    Then we also have to consider that the average CCR dive is a lot longer than the average OC dive, especially when we consider the average 20 to 40 minute pretty fish dive. We average about 240 minutes per dive on CCR, compared to about 90-120 minutes per OC dive in some of the same caves. In other words we make one dive on CCR when we used to make 2 dives on OC. That increases the OC risk for us by a factor of 2 - just based on our OC versus CCR dive numbers per day, and if we compare our 240 minute dive time figure to an average 40 minute open water OC pretty fish dive, the corrected OC risk is 6 times greater.

    Again the risks are different but OC divers dies because they did something stupid - and so do CCR divers. But the way Fock presents the risk is in very general numbers with no consideration for context and differences in conditions and relative dive time.
     
    TONY CHANEY, hroark2112 and tbone1004 like this.

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