Pony Bottles

[Tall Pine Divers]

use to have a pony liked it but never pushed the limits and always have a buddy close by and was abvle to sell the whole thing at a good price so the money went to my new custom trailer to pull behind the wing can get gear for 4 dives in it easyly.

[AandA]

I typically dive with a 20 cubic foot pony.  It is strapped to my primary tank.  I have never actually needed it and plan on never needing it (which is why I have it).    I used to have a 13.  I found that it would lose an unacceptable percentage of it's gas just over the course of turing it on.  When I dive with a pony I ALWAYS turn the air on BEFORE diving.  After about a half dozen dives I'd need to fill the tank.  The twenty gives me a lot more air (in case I ever do need it), and I have to fill it less frequently. 

[mrweekend]

Good to see an old thread revisited! When I did my advanced cert I had a freeflow in superior at 90' and 39 degree water.  I had my Regulator set to give me all the air I wanted and of course it did (Yes, I was as nervous as a preacher in a porn shop ).  Moisture built up and the 2nd stage froze up. This was a high perf reg/cold water reg. But it happens and will happen again.  My Buddy/Instructor had his Pony and we were able to abort safely and even complete the safety stop.  So after that incident I bought one and will always carry it on advanced Dives.  I bought the 30 as the difference in price is minimal and I'll take the air.  For mounting I started out with the back tank mount and last year switched to the staged D-Ring Method.  I won't be going back.

You do want to pressurize your pony before Diving (test it like you would your other regs.) I got sloppy and just dragged it along on a dive.  Having no pressure to the 2nd stage allowed water to creep up the hose.  While reorganizing my gear (this winter)and checking tank pressure I found out that water was still trapped behind the valve seats..  Well. thank goodness for Dive Stores and maintenance. Call it another lesson learned.

[ANewHope]

good discusion about the pony bottles.

I dive frequently in Superior and almost always bring mine on penetration dives. Personally I like mine on my back, one less thing do mess with during the dive; however it does limit the size of holes that I can squeeze through. A couple of points though.

1. Do not use it as a way to extend your bottom time. Had a buddy do this once and he said he nearly drowned.

2. When picking the size you want, get what you want. You can easily get by with a smaller tank, because you can breath for quite awhile from a free flowing reg. I don't know the details, but even from a 13cf bottle you should be able to ascend from a decent (100+ ) depth and still include your safety stop.

[arcFlash]

Maybe someone with more experiance.. but my calculation and RMV (SAC) is .9 if I'm tense and 13cf to get me from 100 has some pucker-factor.

60ft/min from 100 to 60ft and then 30ft/min to 15 +3min + 1min to surface (don't want to rush the last 15)

I calculate that I would need 13.5 cf, that's too tight for me. I'll round that up to 40cf

Did I blow the math? I did it in my head so there is a lot of rounding.