list your pony bottle size options / reasons

[DetectorGuy]

Good conversation in this post. Someone should put together a list (or find a list online) of diver slang/acromyms/euphanisms. "pony bottle", "stage bottle", "bail-out bottle", "spare air", "EBS (Emergency Breathing Systems for Helicopter Evacuation)", "HEED (Helicopter Emergency Egress Device)", and the like... They are all congruent in that they are similar but different. I am still pretty green in the diving community, but "pony bottle" means different things to different people. I thought a pony bottle was just a redundant air source and not an additional air source to extend a dive. I thought the stage bottle was just that, a bottle of gas to breath on during a decompression dive on the ascent. I thought the spare air (EBS and HEED type) was just a placebo that gave a diver a false sense of security that in the event of an out of gas situation that the diver would be alright and everything would be rosey...  it doesnt matter if the glass is half full or half empty if your in the bottom of it with no air...

[Shooter]

             I agree with the Dog on this one, but on deeper dives like on Isle Royale, or most overhead enviorments, usually like to wear doubles. I carry a 30cf pony, have a decent breathing rate, and have found it sufficient, small enough to not be in the way too much, still easy enough to hand off. Would'nt ever invest in a "spare air" WAAAAY too little in volume for anyone in ANY emergency at 100' leaving nothing for the depth (above 30') requiring the slowest assent. (Seriously first breath at 100', second at 60' YIKES!!!! for someone who might be on the verge of panic) Cylinder cost on this group of pony's is typically the same, so would recommend a pony on the larger end of the scale.
[/quote]

I also use doubles when diving deep or on a planned decompression dive. It's really nice not having to worry about running out of air. I carry a 30 ft.³ stage bottle. When I am ice diving locally, I use a single steel 120 and carry my stage bottle. The stage bottle does get in my way when I'm loading my speargun. :-\

I can print my own nitrox stickers  ;D  . I usually just jump in and go  > I monitor my computer of course. When I am doing a planned decompression dive I plan out my entire dive and even have 2 backup plans. It's nice having it written out on your wrist, and not having to do complicated math problems under water while experiencing narcosis. Most of the time it's jump in and go. Why dive air when you can dive voodoo gas! Mamma says voodoo gas is the devil! My sac rate always changes depending on the size of the fish I see,current, or how narced I am at the time.  Here is a simple calculator for those of you who would like to figure out your sac rate.  

[arcFlash]

Tank names are a mess but the names are obvious enough, I'm just careless. I can call it anything but I'll breath it like I want regardless of it's title. If I don't use it, it's pony, if I do, it's stage, if I use it for the o2 at the end, it's deco, no matter.

I breath all my tanks, that way they get used and stay current. it's silly to own a tank simply to not run out of air and pay for a fill/vip once a year and never breath it. Realistically, I can't see ever running out of air. I carry for 1st stage failure and tank to valve o-ring rupture but those are 1000's to 1. I just like having two systems, it relaxes me.

Dive planning. I only plan max depth (floor) and run time. Sample, we agree not to pass X feet and that the dive should attempt a run time at least Y minutes, NDL is observed.

It's also common to plan some form of navigation if the site is known.

[Mr.Pitbull]

But why would someone run out of air at 20, 30 or 40ft? An H valve on your single would be a better preventative if there was a failure. If someone just breathes until there is no more air in the cylinder, there is a bigger problem afoot.

[Mr.Pitbull]

Pretty accurate descriptions, I especially like the last line
it doesn't matter if the glass is half full or half empty if your in the bottom of it with no air...

[DetectorGuy]

Now I am confused!  I have been using the circular NAUI Surface Air Consumption Rate Calculator to check in when I log my dives up till now and thought I should just use this electronic rate calculator to do this from now on as it is very simple to use. When I tried it  and checked against the NAUI calculator there was a huge difference. An example dive was one that Shooter, Art, and I did back on 6-20-09:

118' max depth
68' average depth per both computers (Suunto Vyper and Tusa IQ 700)
80 CF alum with a 19 CF pony (had with but not used)
2600 PSI air used
21 minutes bottom time (this dive was an extreme adrenalin rush for me)
bottom temp was 41 degrees
the visibility varied from 35' to 4' depending on the layer

The NAUI calculator said my sac rate was .40 cu ft per minute
The electronic calculator from the spearfishing website link said my sac rate was 1.07 cu ft per minute.

I haven't taken the time (yet) to do the long hand math to see which is right but I am wondering how I am doing this wrong.

[jleech]

The math agrees with the spearfishing calculator.

I don't know anything about the NAUI calculator, so I couldn't explain the difference.

[DetectorGuy]

Thanks, I always knew I was a heavy breather, but I was kind of content with the "nicer numbers" from the NAUI wheel sac calculator. Now I need to focus more on getting my sac rate under control. I was carrying WAY too much weight as Art and shooter can testify. They encouraged me to drop 10 pounds of carried weight since then. My sac rate varies dive to dive from .54 to 1.07 with the spearfishing calculator and seems to average about .79. Thanks again.

Anybody wanna buy my "Slightly used" Naui sac rate calculator wheel?... No?.... anyone?... ok I will use it for a secchi disk ;D

[DetectorGuy]

So to play the "out of air" scenario from 130' coming up at 1' every 2 seconds (Not counting the 1 minute half stop at 65' or the 3 minute safety stop at 15' for now) it would take me 4 minutes and 20 seconds to ascend 130'. Now add 4 minutes for the half stop and safety stop, and I would be looking at 8 minutes and 20 seconds to get to the top total time. Round up to 9 minutes to be conservative and my sac rate could be as much as 2.0 cu ft per minute and I would still have a little gas left in a 19 cu ft pony bottle.

Even for me (the heavy breather) the crap would really have to hit the proverbial fan for my sac rate to climb that high... any thoughts?

[SCUBA Dog]

Detector Guy

The NAUI SAC Rate Calculator gives you your air consumption rate in PSI per minute, not cubic feet per minute. So your numbers are correct, except that it would be 40 psi/minute. This number is based on the psi consumed and therefore is tank specific. If you change the size of your tankthe end result will change. Important to know if you are using the value to plan a dive and are changing tank size. If you want cubic feet per minute, you need to convert it.

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