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Default Nitrox Setting for Perdix AI in OC Mode

Discussion in 'Shearwater Research' started by g2, Apr 13, 2019.

  1. g2

    g2 Divemaster

    # of Dives: 500 - 999
    Location: Port Townsend, WA
    558
    83
    28
    I'm shopping around for dive computers and have a quick question that I haven't yet found in the manuals...

    When you turn on the Perdix AI, what is the default gas mix setting? Is it the same as the last time you used the computer, i.e., if I dove EAN 32 last week does it come up the same, or reset to air?

    I typically dive the same mix over and over again, whether it's an hour or a month between dives. I've been burned by other computers that reset the mix after some non-diving interval.
     
  2. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    7,103
    4,500
    113
    It stays on your last-entered info, just like it should!:)
     
    rongoodman and g2 like this.
  3. TerryC

    TerryC Master Instructor

    # of Dives: 2,500 - 4,999
    Location: St Kitts, West Indies
    186
    93
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    Last active gas is what it stays set at.
    Whatever you used the last time is always what it defaults to on turn on.
    Nice thing is you can set up your gases, then switch them on or off at will.
    So an easy, quick, switch if your last active gas is not the one you are diving with now.
     
    g2 likes this.
  4. rongoodman

    rongoodman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Albany, NY
    4,799
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    Recreational computers resetting gas mixes behind divers' backs might be the number one cause for lock-outs on liveaboard trips, truly an awful idea!
     
  5. Brules

    Brules Loggerhead Turtle

    # of Dives: 200 - 499
    Location: Oklahoma City
    1,724
    654
    113
    So I have been arguing with SW's CS about the issue of in REC mode - if you go into DECO and have more than one gas on, the computer may switch to one of the other gases as since you have the other gases (up to 3) ON - it assumes you are carrying them.

    My argument is - in OC recreational mode, you should not ever assume/allow that to happen as they is a technical dive and NOT rec (carrying multiple bottles/gases).

    They stand by their argument that its a "tech" based computer / where they came from. My point is in REC mode it shouldnt be allowed to auto switch.

    Heck even in tech mode I dont think I would ever want it to even think about auto switching..........

    Whats everyone think? Should a rec mode allow for auto gas switching like that? I think in Rec you should be able to program 3 gases and switch between them only when on surface. If you want to switch at any dive it should have to be in TEC mode.

    Thoughts?
     
  6. rabe

    rabe Barracuda

    # of Dives: I'm a Fish!
    Location: Brisbane
    426
    195
    43
    No it doesn't...
     
  7. TerryC

    TerryC Master Instructor

    # of Dives: 2,500 - 4,999
    Location: St Kitts, West Indies
    186
    93
    28
    You are mistaken
    There is no auto switching.
    Nothing is done "behind the divers back"
    The Shearwater indicates at the correct MOD that you have a better gas available if you have one turned on.
    Any gas switching has to be done manually.
    The only point to note is that your TTS is based on you switching gases as they become available at MOD.
    Your actual deco time is not affected by the gases available. Deco time changes only if you select a different gas.
    Best practice on any dive computer is to check that the mix set on the computer agrees with the gas in your tank. Basic part of gear check.
     
  8. TerryC

    TerryC Master Instructor

    # of Dives: 2,500 - 4,999
    Location: St Kitts, West Indies
    186
    93
    28
    Most stay on last setting.
    I have seen a couple of models of basic computers that will switch back to air when no fly time clears.
    Sorry, can't remember what they were.
     
  9. g2

    g2 Divemaster

    # of Dives: 500 - 999
    Location: Port Townsend, WA
    558
    83
    28
    Do you mean it switches automatically (which would be a huge safety issue), or simply permits a rec diver to switch manually (desirable behavior)?

    @TerryC and @rabe think it doesn't switch automatically.
     
    rabe likes this.
  10. outofofficebrb

    outofofficebrb HARRO HUNNAYYY

    # of Dives: 200 - 499
    Location: San Francisco, California
    2,175
    1,390
    113
    Stays at last one you were using. It will also remind you what it is - the default bottom row I have shows it as Air/NX%, T1 pressure remaining, and sac rate.

    So when I turn it on it’s the same and I can visually confirm it’s what I need it to be. If not, it’s an easy change.
     
    rabe likes this.

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