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Zero vis air management

Discussion in 'Public Safety Divers/Search and Rescue' started by muddiver, Oct 5, 2007.

  1. muddiver

    muddiver Divemaster

    # of Dives: 500 - 999
    Location: West Coast USA
    Ok, dumb question time.

    Since most PSD teams use SCUBA to do search, rescue and recovery work, how does your team train to monitor the amount of breathing gas remaining in the diver's cylinder during a zero visability dive? And I am not talking a low vis 6" to 3' dive, I am talking a "you run into things and really can't tell what they are" dive.
  2. do it easy

    do it easy Assistant Instructor

    # of Dives: 500 - 999
    Location: Chicagoland, USA
    I just grab my SPG hose and shake it a bit- if it feels limp like old lettuce- it's time to go! :D
  3. Charlie99

    Charlie99 Solo Diver

    # of Dives: 500 - 999
    Location: Silicon Valley, CA / New Bedford, MA / Kihei, Maui
    The black water or no-lights method used by some military guys is to dive a set of doubles with the isolator closed.

    When you run out of air, you know you have used up 1/2 of your air. Open the isolator a few seconds and then close it. When you run out again you are down to 1/4 of your air.

    What would be a much better system is the vibrator and bell sort of gizmo on a fireman's breathing apparatus. Is there an underwater version of that?
  4. stuck

    stuck Public Safety Diver

    About 80% of our dives are black, mostly all are under 30 ft, even in the worse vis i dont think its ever been a problem to see your gauge.Once you wipe the muck off the glass.I have had to hold it up to my aga with a light, but really were most of our bad call outs are if you run out you just stand up and switch out.
  5. Boater Dan

    Boater Dan Barracuda

    # of Dives: 100 - 199
    Location: Western PA
    There is a need for the divers to take some responsiblity for their air consumption rates and know what time period they can achieve from the cylinder size they dive. Due to thermal considerations along with stress of recoveries, our policy has been to limit divers to 20 minute intervals. (Note that our dives are at worst 40' in depth) Depending on the number of divers and conditions, they will have an opportunity to get back into rotation after a break and a fresh tank. If somone burns through an 80 in less than 20 minutes, they probably should not be participating in these types of dives.

    By implementing this time limit, it has worked out well for us.

  6. Charlie99

    Charlie99 Solo Diver

    # of Dives: 500 - 999
    Location: Silicon Valley, CA / New Bedford, MA / Kihei, Maui
    For zero viz dives where the diver cannot see a watch, I assume you are doing tethered dives and terminate the dive via line pull signals. Correct?
  7. *Floater*

    *Floater* Solo Diver

    # of Dives: 100 - 199
    Location: Here, there and everywhere
    One of those masks with an air integrated computer display, like the oceanic datamask hud, might come in handy, though they are expensive.
  8. bleeb

    bleeb Photographer

    # of Dives: 100 - 199
    Location: Ottawa, Canada
    Not a PSD and never dove absolutely zero vis, so I hope you'll excuse the noob question, but if you have a fluorescent gauge, can't you press the gauge against your mask? Or are there reasons not to do this?
  9. Yotsie

    Yotsie Public Safety Diver

    # of Dives: 500 - 999
    Location: Modesto, CA
    If we are in zero viz and using self contained, we limit each diver's bottom time to 25 mins. We usually work with surface supplied air in zero viz when we can not read our guages. We pretty much know what body of water is going to require each system.
  10. redacted

    redacted Guest

    Sounds like a good place for a J-valve or a scubapro Mk7.

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