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Burning the O2 clock

Discussion in 'Advanced Scuba' started by Meister481, Oct 16, 2010.

  1. Meister481

    Meister481 Tech Instructor

    # of Dives: 0 - 24
    Location: Greenwood, Indiana
    642
    4


    A ScubaBoard Staff Message...



    Sounds like a pretty standard 3 hour Jackson Blue dive.

    Double 125's at 3900= 368 cubes
    3 AL 80 stages at 3300= 254 cubes
    40 of O2 at 3000= 40 cubes of deco gas
     
    Last edited by a moderator: Oct 17, 2010
  2. ucfdiver

    ucfdiver DIR Practitioner

    # of Dives: 500 - 999
    Location: Orlando, FL
    3,338
    501
    That sounds like a ton of bottom gas and slim deco gas to me...
     
  3. Meister481

    Meister481 Tech Instructor

    # of Dives: 0 - 24
    Location: Greenwood, Indiana
    642
    4
    If you follow a deco program, yes, but when you do the actual dive, you don't need much more than half the deco gas. Lost deco gas and you've got tons of back gas to compensate.

    I'd rather have too much BG on a scooter dive than not enough. That dive is pushing the pulmonary O2 limit so I do long BG breaks and it works out fine. Can't stay on O2 for long with this dive, so why carry extra O2 you can't use?

    I use a weird deco schedule at times.
     
  4. ucfdiver

    ucfdiver DIR Practitioner

    # of Dives: 500 - 999
    Location: Orlando, FL
    3,338
    501
    Just curious, but how far do you plan to swim in the case of a scooter failure or siltout?

    At Manatee Springs, we brought almost 2x the deco gas needed, because swimming for a bit could rack up more deco than can be dealt with if we planned it scootering both ways.

    I only ask because I know it's commonly overlooked to carry enough deco gas to swim out of the cave. Everyone carries enough bottom gas. Not sure why that is.
     
  5. Meister481

    Meister481 Tech Instructor

    # of Dives: 0 - 24
    Location: Greenwood, Indiana
    642
    4
    Think of it this way, No matter how much deco I carry, I can only use about 30 cubes before I burn my O2 clock.

    Planning is done properly, I've done all the math, empirical testing and I can make it out in a full silt out with the loss of half my backgas. Including Deco with lost gas. I don't breathe much, so that helps.
     
  6. ucfdiver

    ucfdiver DIR Practitioner

    # of Dives: 500 - 999
    Location: Orlando, FL
    3,338
    501
    Do you actually believe that? (o2 clock that is)
     
  7. Cave Diver

    Cave Diver Divemaster

    17,866
    2,518
    Can you elaborate on that?
     
  8. Meister481

    Meister481 Tech Instructor

    # of Dives: 0 - 24
    Location: Greenwood, Indiana
    642
    4
    Not really the venue.

    If I hit around 90% on the O2 clock, I get the chokes and my lungs burn. I guess I'm sensitive to O2. No matter what you believe in or if it differs to how you dive. It works for me. I have to be careful with my O2 consumption. Why carry gas that will cause me to be uncomfortable after the dive. I'll trade a longer deco with extended air breaks for crispy lungs.
     
  9. LiteHedded

    LiteHedded Contributor

    4,075
    920
    what ppo2 are you running on the bottom?
     
  10. Meister481

    Meister481 Tech Instructor

    # of Dives: 0 - 24
    Location: Greenwood, Indiana
    642
    4
    Try to stay between 1- 1.2

    Best trade off I have found between deco time and O2 exposure.
     

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