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Teric takes 2 mins to clear 1 min of deco

Discussion in 'Shearwater Research' started by Steyr, Jul 4, 2020.

  1. Steyr

    Steyr Nassau Grouper

    # of Dives: 200 - 499
    Location: Melbourne, Australia
    75
    38
    18
    Yesterday on a dive I had 12 minutes of deco to clear at 6m. Even though my buoyancy had me sticking bang on 6m the entire stop (give or take .3m either side), it took 24 minutes to clear that 12 minutes of deco.

    I suspect I've had similar issues with this computer before. I normally have my last stop at 3m but sit at around 4-4.5m, so I always figured it took longer to clear because I was a bit deeper. But perhaps part of it is the issue that became clear at 6m.

    Has anyone else encountered this, or have any ideas on what might be the problem?
     
    markmud likes this.
  2. grantctobin

    grantctobin ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Chicago
    733
    423
    63
    When on the dive did you “have” 12 minutes of deco? When you left the bottom to begin your descent? After you were at 6m? Which glasses are programmed into the computer and “on” vs what gasses you used on that day?
     
    couv, markmud and NAM001 like this.
  3. runsongas

    runsongas Great White

    # of Dives: 500 - 999
    Location: California - Bay Area
    4,230
    1,894
    113
    most likely a 2nd richer gas was enabled which you did not switch to
     
    rsingler, couv, markmud and 2 others like this.
  4. Steyr

    Steyr Nassau Grouper

    # of Dives: 200 - 499
    Location: Melbourne, Australia
    75
    38
    18
    12 minutes when I reached the 6m stop. (13 when I left the bottom).
    I did have a 21, 32 and 60 mix "on", though wasn't carrying them. My only carried and active gas was 27%, and checking the logs shows it stayed on that the entire dive.
     
  5. grantctobin

    grantctobin ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Chicago
    733
    423
    63
    Because you had the gas as “on”, the computer will assume you could have switched to 60% when it became the appropriate mix.
     
    Robbyg, markmud and rjack321 like this.
  6. Steyr

    Steyr Nassau Grouper

    # of Dives: 200 - 499
    Location: Melbourne, Australia
    75
    38
    18
    Ah, so with the 60 mix "on", the deco would have been calculated assuming I was going to switch to that? But of course I didn't. That would make sense.

    Note to self - always turn off gases not in use.
     
  7. Steyr

    Steyr Nassau Grouper

    # of Dives: 200 - 499
    Location: Melbourne, Australia
    75
    38
    18
    Thanks guys! Makes sense, and lesson learned. :thumb:
     
    JimBlay and lynnpartridge like this.
  8. tmassey

    tmassey Manta Ray

    # of Dives: 500 - 999
    Location: Shelby Township, MI USA
    611
    792
    93
    This was a lesson my instructor mentioned in my Trimix class: He strongly suggested not only turning the gas off, but *deleting* them (set them to 00/00) when you were done with them. When they're programmed, you can accidentally turn them on. Deleting them means you can't even accidentally turn them on.

    Review: TDI Normoxic Trimix with John Chatterton, November 2019

    12 minutes of deco turning into 24 is bad enough, but I imagine with longer decos that could become deadly, especially if you're reliant on your computer for a dive plan... (Which was a topic in my class described in that link above.)
     
    markmud and wnissen like this.
  9. Steyr

    Steyr Nassau Grouper

    # of Dives: 200 - 499
    Location: Melbourne, Australia
    75
    38
    18
    Yes, same.
    And of course I've had this same "problem" when I've done the classic mistake of switching gases and not switching my computer to the new gas, only to realise when my deco stop starts extending out longer than it should. I should have put two and two together over this latest example, and known the cause. I feel a bit foolish over this. I really should have known better (and really I do!).:facepalm:

    Oh well. An embarrassing stuff up is a good way to counter overconfidence. :thumb:
     
    James79 and JimBlay like this.
  10. al248005

    al248005 Solo Diver

    # of Dives: 200 - 499
    Location: Bridgeport, Ohio
    748
    145
    43
    This shows up in the dive planning mode too I've noticed. If you have more than one gas on it will show a switch midway through the dive. You have to turn everything off except what you are using for it to plan correct as well.
     
    markmud likes this.

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