• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Pony bottle ascent schedule?

Discussion in 'Advanced Scuba' started by dstrout, Mar 30, 2010.

  1. svs

    svs Solo Diver

    # of Dives: 200 - 499
    Location: Philadelphia, PA US
    151
    12
    I would go:
    130 -> 15 @ 30 ft/min
    15 – 5min+ stop
    There is one question though. What if I am 5-7 min (hard to imagine more then 7) away from the ascent line. I have to make pretty fast decision: to go to the line and may be accumulation few deco minutes, or to go up and surfacing away from the boat, or inflating sausage (if I also have 150 ft line on me) before ascent.
     
  2. Blackwood

    Blackwood DIR Practitioner

    # of Dives: None - Not Certified
    Location: Southern California
    5,535
    318
    Not much of a question to me. If you're bailing to a small source of gas (i.e. a pony bottle), you shouldn't be dilly-dallying at depth.

    Is coming up a known upline a concern? It absolutely can be. But again, drowning is almost certain death. If you get blown off the line, you have a chance of being recovered.
     
  3. dstrout

    dstrout Registered

    # of Dives: 50 - 99
    Location: Edgewater, MD
    56
    0
    Cool - thanks to all. Doh! Saying 32% is what I get for posting first thing in the morning. 28% is PPO2 of 1.4. Sorry! I do know better. :)

    So I guess the bottom line is that since you're on the way up, the difference between 21% and 28% isn't going to matter that much.

    I do have a gas switching computer, but since it's hoseless, I wasn't planning on putting a $400 transmitter on a pony bottle.

    thanks,
    dave.
     
  4. SkimFisher

    SkimFisher Contributor

    831
    33
    It's one button push on mine...easily done on the fly. But I digress.
     
  5. SkimFisher

    SkimFisher Contributor

    831
    33
    Your bottles don't need the transmitter for your computer to work. My other DC is hoseless but I don't use it with the transmitters. The transmitters do one thing - monitor how much gas you've got. They don't care what's in the bottle, just that there's something in the bottle.
     
  6. Blackwood

    Blackwood DIR Practitioner

    # of Dives: None - Not Certified
    Location: Southern California
    5,535
    318
    Fair enough. All the computers I've used have been fairly... cumbersome.
     
  7. SkimFisher

    SkimFisher Contributor

    831
    33
    I can relate. My other one is a PIA.
     
  8. TSandM

    TSandM Missed and loved by many. Rest in Peace ScubaBoard Supporter

    36,349
    13,623
    1. I would always be sure that the pony bottle I was carrying would permit a normal ascent, with normal stops. The gas in it, as has already been explained, doesn't matter in the scenario given.

    2. If you are diving where you MUST get back to the upline to do a safe ascent, your gas planning has to take that into account. The pony must contain enough to return from the further point contemplated on the dive, or you dive with a buddy, and dive thirds on usable gas. These are not beginner dives.

    The bottom line is that, in my opinion, PLANNING should mean that you should never face a situation where you have to make an abrupt and possibly unsafe change in your procedures because of a gas failure.
     
  9. Web Monkey

    Web Monkey Omniheurist ScubaBoard Supporter

    # of Dives: I just don't log dives
    Location:
    6,921
    17
    You need to plan your dive using the gas you're bringing.

    If it's a no-deco dive, then you can fill your pony with air and do a normal ascent if you lose your main cylinder.

    Since a normal ascent from recreational depths shouldn't take more than a few minutes from the bottom up to your safety stop if you were respecting the no-deco limits, it shouldn't be a big deal if you were breathing 32% for the last hour and are now breathing 21% for the last 3 minutes.

    If this is a deco dive, you need to have already planned for this contingency and have prepared an ascent plan that takes into account whatever mix is in your pony (at this point it's a deco bottle).

    If it's a deco dive and you lost your back-gas and don't have a good buddy and a good plan, you're on your own.

    Terry
     
    Last edited: Mar 30, 2010
  10. muddiver

    muddiver Divemaster

    # of Dives: 500 - 999
    Location: West Coast USA
    2,630
    105
    My computer will switch to a second mix if I stop breathing off the primary (yes, it's intagrated). The only fumbling is trying to find that darn pony regulator when the primary goes dead. :shocked2:
     

Share This Page