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Recommended Pony Bottle Size

Discussion in 'Advanced Scuba Discussions' started by Wolver, Jul 21, 2010.

  1. Wolver

    Wolver Nassau Grouper

    # of Dives: 100 - 199
    Location: Sylvania, Ohio
    73
    4
    0
    Just wondering what you all think. I just acquired a 50 cubic foot tank to be used as a pony. I see alot of divers using the 40 cft pony tanks. I plan on side slingin it. Do you think there will be any noticeable difference between those 2 tanks while underwater besides the difference in the amount of air. The 50 is much shorter and wider than the 40. I dont have any experience diving with ponies. Thanks for any help.
    Wolver
     
  2. String

    String Master Instructor

    # of Dives: I just don't log dives
    Location: Grand Cayman
    8,509
    365
    83
    You're doing this the wrong way. The only sensible way to know what size pony bottle is needed is to work out your own air consumption THEN work out what maximum depth that pony will get you to the surface safely from.

    Then you now how deep you can safely go while relying on one of those for bailout.
     
  3. Wolver

    Wolver Nassau Grouper

    # of Dives: 100 - 199
    Location: Sylvania, Ohio
    73
    4
    0
    I plan on staying within Rec depths, I know that a 50 or a 40 will get me to the surface from 120ft. I am more concerned with the rigging, and drag underwater? I am thinking a 40 might be easier to sling and swim with but I dont know. Thanks.
     
  4. deepwater

    deepwater Solo Diver

    # of Dives: I'm a Fish!
    Location: San Antonio
    257
    1
    0
    If you know your scr I would do the math, or find the spreadsheet that's over in the solo divers section. Staying within rec limits, I sling a 20cf. The pony is meant to be a bailout not an additional air source, take only what you need.

    dw
     
  5. packman

    packman Manta Ray

    # of Dives: 200 - 499
    Location: southeast of disorder
    716
    0
    16
    Only way to really know is to rig it and dive somewhere controlled like a quarry or pool to see how it feels. Borrow a 40 as well, if you can, to see if there's any noticeable difference for you.
     
  6. Wookie

    Wookie Secret Field Agent ScubaBoard Business Sponsor

    29,295
    47,472
    113
    As others have said, detirmine how much air you'll need to make the surface. A 50 is absolutely the wrong cylinder for a pony. Remember, a pony is an emergency air source, not an extend-a-dive kit. A 50 will not sling easily or comfortably (too short and fat) and you'll find it more of a pain in the butt to dive with than leaving it ashore. It won't do you any good onshore.

    I dive with a 19 cf, my wife uses a 9 cf (argon bottle) tank. Either will get us to the surface comfortably doing an NDL dive. Hers is carried n an argon bottle rig on her backplate, so it is not detachable. Mine is rigged with a tiger gear mount to my HP-100 so I can hand it off if someone else needs it.
     
  7. mksmith713

    mksmith713 Solo Diver

    # of Dives: I just don't log dives
    Location: Jupiter,Fl
    991
    6
    0
    Yeah, a 50cf isn't the way to go.
    My daughter dives with 50's....they're not designed to be slung.
    If you're staying within NDL's I can't see needing anything bigger than a 30cf and that's if you're an air hog.
    More than likely you'll use a 19cf.
    Do the math and you'll know.
     
  8. Wolver

    Wolver Nassau Grouper

    # of Dives: 100 - 199
    Location: Sylvania, Ohio
    73
    4
    0
    Well, it looks like I will be looking to sell it or trade to a smaller tank. At first I was thinking just use it for bailout, then if I decided to go tech, it could serve as a deco bottle. It was a spur of the moment purchase cause I will probably not go tech. Thanks for all your input. Really helps.
     
  9. lowviz

    lowviz Solo Diver ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Northern Delaware or the New Jersey Turnpike
    7,239
    4,130
    3

    With a SAC of 1.5 (huffing REALLY hard) I get:

    at 130' dive goes bad
    30 sec to figure out what happened
    30 sec to find and signal buddy
    60' / min ascent
    1 min safety stop

    23 cuft. and 500 psi of air left in the bailout



    Which is why I really like my tidy 19cuft.
     
  10. lowviz

    lowviz Solo Diver ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Northern Delaware or the New Jersey Turnpike
    7,239
    4,130
    3
    -not so fast, you already took the financial hit. Keep it filled with air, buy a transfill whip and use it to top-off your bailout bottle. Also nice to have that size around if you want to do a quick dive (a recovery, repair somebody's pool) and not partially drain your primary tank(s).
     

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