Pony Bottle

[AndyNZ]

I would say a 30 or a 40 cu ft tank, but definitely not a 13 or 19. Depends what you want to put in it.

I have both 30 and 40 cu ft tanks, the 30 is my usual pony and I tend to use two 40 cu fts for deco, one for 50% and one for O2.

My other half uses the 30 cu ft for O2, and a 40 for 50%.

30 cu ft is way too small for a mix like 50%, but is fine for moderate deco using O2. In reality, you won't notice any difference between carrying a 30 or a 40, so the suggestions to go the larger tank will give you flexibility.

 

[Atomic_Diver]

Oh no!! Not another pony thread, mabey all the pony/spare air threads should be merged into 1?... A decent size deco bottle on the other hand would be an Alummnium 40 cu ft tank

 

[DCBC]

I suppose that it's worthwhile to define what we mean by a Pony Bottle? Traditionally this referred to a redundant supply of breathing gas which was used for an emergency ascent in case of an emergency. This air source was not figured into the diver's air management and is kept separate for emergency use only.

If the OP wants a small cylinder for future decompression purposes (for use in the air management plan), I agree with many others in-that it should be 40 cu.ft. I do not however consider this to be a Pony Bottle.

If the OP's current level of diving does not lean toward decompression diving, or this is not known to be "on the horizon," I would promote a smaller version. A Pony Bottle with a 13 to 20 cu ft capacity may be a better choice. As these may be mounted on the main cylinder, I would ask the OP to consider how he wishes to carry the bottle and choose a size of cylinder suitable to his gear configuration and needs.

 

[RJP]

Maybe all the spare air threads should be merged into 1?

"Spare Air? Did you say Spare Air? Why, my brother dives with a Spare Air! Do you know my brother? No? Then why do you go round talking about my brother? I'll have you know my brother is one of the finest guys to have ever walked in shoe leather. My brother was an honor student at school! Go ahead, say something nasty about my brother. Say something like 'he shouldn't get a parole!'...go ahead!"

The Original Spare Air Discussion:

 

[200 Bar]

I vote for AL40....

 

[bletso]

I have been teaching advanced and beyond for years. For the recreational diver going below 20 MSW i have always required a 13 or 19. In all my advance classes I have have had the students switch to the pony and do a normal ascent from a minimum of 30 MSW. I have yet to have any of them empty the pony and this is doing a 3 min safety at 6 MSW. Oh, BTW, we dive cold dark quarries.

A 13 is adequate down to 30 MSW but I prefer a 19. The 19 costs the same, adds no more drag and if you are diving an Al80 it represents about a 25% reserve! Both sizes mount easily to the tank with many different attachment schemes. We mount the pony upside down so the diver can reach it and use an octo hose to add the necessary length. (Oh, get rid of the octo on your primary reg. 2nd stages are a real weak point in equipment.)

A lot of people have given me crap over the years with the pony requirement below 20 MSW, but until we learn to breathe water, its my rule. As has already been pointed out the pony is never calculated as part of ones gas supply. It is an emergency supply which you may carry all your dive career and never need it. But when you do, well it beats all the other scenarios.

Keep in mind; no one has expired from too much air on a dive, but not enough can be hazardous to your health.

Dive safe

Dale
ahhome

 

[Atomic_Diver]

"Spare Air? Did you say Spare Air? Why, my brother dives with a Spare Air! Do you know my brother? No? Then why do you go round talking about my brother? I'll have you know my brother is one of the finest guys to have ever walked in shoe leather. My brother was an honor student at school! Go ahead, say something nasty about my brother. Say something like 'he shouldn't get a parole!'...go ahead!" The Original Spare Air Discussion:

fine the yellow 3.0, and 1.7 cu ft system/pony threads...

 

[Red Sea Shadow]

I suppose that it's worthwhile to define what we mean by a Pony Bottle? Traditionally this referred to a redundant supply of breathing gas which was used for an emergency ascent in case of an emergency. This air source was not figured into the diver's air management and is kept separate for emergency use only.

If the OP wants a small cylinder for future decompression purposes (for use in the air management plan), I agree with many others in-that it should be 40 cu.ft. I do not however consider this to be a Pony Bottle.

If the OP's current level of diving does not lean toward decompression diving, or this is not known to be "on the horizon," I would promote a smaller version. A Pony Bottle with a 13 to 20 cu ft capacity may be a better choice. As these may be mounted on the main cylinder, I would ask the OP to consider how he wishes to carry the bottle and choose a size of cylinder suitable to his gear configuration and needs.

What he said.

 

[Atomic_Diver]

Why not couldn't the OP say What would be a good size deco bottle to have in the future, as my horizon calls for deco training...?

 

[Atomic_Diver]

Honestly IMO if you are looking for an compleately seperate redundant "alternate air source" then go with an (AL) Alumminum 30 cu ft... which is just perfect for any little OOA, or other emergancy a recreational diver may have.. Lets just say your pushing your limits for 8 mins on Air at 140' (10' deeper than you should be) and you had a compleate gas supply loss at 7 mins on the dot, an AL 30 will get you (and only you) to the surface with a stop at half max depth for a min, and a stop at 15' for 3-5 mins with probabley a little left as "reserve"