Pony Bottle Regulator Setup

Please register or login

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. Log in or Register now!

Capacity of a redundant air source is dictated by two factors:

1) The diver's air consumption rate.

2) The worst-case scenario time that the redundant air source would have to sustain the diver.

That worst case would be a loss of primary breathing gas at the end of the bottom phase of the dive: max depth, max nitrogen loading, max time to surface (ascent and deco obligation).

- A responsible diver would also factor in the capability to share air during that ascent, at least doubling the volume of redundant gas carried, from that previously.

- Air consumption would be prudently calculated at an accelerated consumption rate, in expectation of some incident-stress on that ascent.

For me, any deep, deco or overhead environment dive is planned according to (at least) rule-of-thirds. I wouldn't be using a pony for such dives - I would have full doubles redundancy. However, if I were to use a pony, the volume would represent at least 1/3rd of my main tank. The dive would be planned/undertaken on rule-of-thirds, so I'd have a 1/3rd contingency reserve in my primary tank and an 1/3rd redundant reserve in my pony.
Really? now a diver is not responsible unless he carries in his pony bottle, DOUBLE the air he needs to get to the surface??? I think that is way over conservative for recreational diving.... How about diving inside wrecks with zero redundancy? Is that responsible? reference this video you posted before???? http://www.scubaboard.com/forums/ad...wreck-danger-graphic-video-demonstration.html
 
a 2.7 litre cylinder holds about 600l gas so you would then have sufficient and some spare. The cylinder is relatively small but holds sufficient gas. I cant see how a 6 cu ft cylinder holds enough without running out of air or assuming a very low SAC rate and high ascent rate etc. Anyway they are my thoughts and clearly others differ on the matter. Yes I have dived to 45 m on an 11 litre cylinder with no emergency and no backup gas. Doesn't make it right or smart, just means yes you can, but I had no other redundancy other than my buddy, so I could do the above dive with a 0 cu ft sling, but would prefer not to.

---------- Post added March 25th, 2013 at 02:39 AM ----------

And yes you are right one should include a buddy as part of the reserve in recreational diving which is the accepted norm
 
Dumpster... that's a training video... it's meant to portray recreational divers getting into trouble. What do you persist in finding hard to grasp about that? Going to the movies must really freak you out sometimes huh? :wink:



...and yes... given the parameters I mentioned (deep/deco/overhead), then double to get to the surface is quite prudent. It accounts for many factors, not least the ability to share air. Is it acceptable to lose that capacity to share air? when? where? why?
 
Dumpster... that's a training video... it's meant to portray recreational divers getting into trouble. What do you persist in finding hard to grasp about that? Going to the movies must really freak you out sometimes huh? :wink:



...and yes... given the parameters I mentioned (deep/deco/overhead), then double to get to the surface is quite prudent. It accounts for many factors, not least the ability to share air. Is it acceptable to lose that capacity to share air? when? where? why?
It is definitely acceptable to lose that capacity when making recreational videos!
 
I don't need to do the math (although I can do it and do run my rock bottom spread sheet for planing).

I have done wreck ally multiple times, always solo, always with a 13 cu ft pony. Its a hard bottom, the biggest issue is it can be cold and you have currents, so that can surprise some divers. Awesome dives.

I have practiced using a 6 cu ft bottle from 75ft more times than I can count (admittedly in 60F) and I like it for travel. My drills use 1/2 the bottle to get to s/s.

Its not the best tool over 80', you can make it work but you need to understand its limits. (Any tool can be the right tool, just measure once & hammer into place :D). The key if you play with the numbers is you must start you ascent immediately and proceed at 60FPM to 60', then 30FPM to the surface. If you waste even a minute at depth, your done for. There is no margin for a partially filled bottle, there is no margin for fiddling around at depth. There is a possibility you do a s/s it may get cut short with a 2nd OOA. If you don't drill enough to ascend immediately or you insist on deep stops or you want a slow ascent or you want padding find something bigger.

---------- Post added March 24th, 2013 at 03:18 PM ----------

It looks like I'm going to have to replace my 6 cf "toy bottle" with a much bigger one. I purchased it years ago on the recommendation of the instructor that was certifying me for AOW, and luckily haven't had to use it once. Glad at least I didn't fall for the hype of the Spare Air, which also was more expensive then.

Hang on to it. Sooner or later you may find the 6 an ideal size for a travel bottle. While bigger tends to be better, you can very quickly get to the point where you don't dive with the big one because of the hassle factor when traveling. IMO, diving with a small redundant air source is safer than diving without one because you left it at home. Just understand what its limits are and practice often.
 
Do the math.. do the numbers and you tell me.....I would do the dive with a 6 no problem, but I would not plan on running out of air and going into deco. I avoid deco with a 6.. but let's see your numbers..

No one plans to dive into an OOA situation (unless they were completely reckless). My bad though, what I should have said was an OOA emergency resulting from a regulator malfunction, not a result of deliberate disregard of air pressure, but my fingers were typing faster than what my brain was dictating 😴. I meant to convey a "worst case scenario".

---------- Post added March 24th, 2013 at 01:34 PM ----------

I don't need to do the math (although I can do it and do run my rock bottom spread sheet for planing).

I have done wreck ally multiple times, always solo, always with a 13 cu ft pony. Its a hard bottom, the biggest issue is it can be cold and you have currents, so that can surprise some divers. Awesome dives.

I have practiced using a 6 cu ft bottle from 75ft more times than I can count (admittedly in 60F) and I like it for travel. My drills use 1/2 the bottle to get to s/s.

Its not the best tool over 80', you can make it work but you need to understand its limits. (Any tool can be the right tool, just measure once & hammer into place :D). The key if you play with the numbers is you must start you ascent immediately and proceed at 60FPM to 60', then 30FPM to the surface. If you waste even a minute at depth, your done for. There is no margin for a partially filled bottle, there is no margin for fiddling around at depth. There is a possibility you do a s/s it may get cut short with a 2nd OOA. If you don't drill enough to ascend immediately or you insist on deep stops or you want a slow ascent or you want padding find something bigger.

---------- Post added March 24th, 2013 at 03:18 PM ----------



Hang on to it. Sooner or later you may find the 6 an ideal size for a travel bottle. While bigger tends to be better, you can very quickly get to the point where you don't dive with the big one because of the hassle factor when traveling. IMO, diving with a small redundant air source is safer than diving without one because you left it at home. Just understand what its limits are and practice often.

Yes, I agree. At this point it wouldn't make financial sense to sell it either (it would probably bring all of $15.00). I will just simply buy a bigger one and use that.
 
I will pay you $20 and show you how to do the math.
 
Eh, yes.... On second thought, no thanks! 😁

I understand and have figured out the math, after it was clearly explained to me by people better than me a few replies earlier.
 
Eh, yes.... On second thought, no thanks! 

I understand and have figured out the math, after it was clearly explained to me by people better than me a few replies earlier.

Oh, I didn't see any posts between yours and mine?
 
I'm sure you did, I just haven't figured out if you we're trying to be funny, or just trying to be a smart a$$!

So which is it? You can tell me, I can take a joke.
 

Back
Top Bottom