basic pony bottle questions

[ChrisA]

Some basic questions:

1) Within the limits of 100ft depth and NDL. When would you consider taking a pony bottle as a redundent air source? Every dive, never at those limits. something in between?

2) I'm resonably sure I know how to compute how much air I'd need to acend from a given depth and do a safty stop. But is there a generally accepted amount of reserve. Seems to me a 500PSI reserve is meaningless as some ponies might be 13 or 40 cu ft. Seems you'd want to measure reserve in cu ft of air at surface. (You see, I'm asking in an indirect way "how big of a bottle?") Or maybe just figure on a 15% reserve.

3) Where is best place to keep the pony's regulator? Like an octo but on other side or rolled up an in a pocket?

What I'm really looking to find out here is if there is a wide range of opinion or if most people are doing things the same way.

 

[Diver0001]

Some basic questions:

1) Within the limits of 100ft depth and NDL. When would you consider taking a pony bottle as a redundent air source? Every dive, never at those limits. something in between?

2) I'm resonably sure I know how to compute how much air I'd need to acend from a given depth and do a safty stop. But is there a generally accepted amount of reserve. Seems to me a 500PSI reserve is meaningless as some ponies might be 13 or 40 cu ft. Seems you'd want to measure reserve in cu ft of air at surface. (You see, I'm asking in an indirect way "how big of a bottle?") Or maybe just figure on a 15% reserve.

3) Where is best place to keep the pony's regulator? Like an octo but on other side or rolled up an in a pocket?

What I'm really looking to find out here is if there is a wide range of opinion or if most people are doing things the same way.

These answers correspond to my personal way of doing things. Keep in mind that every person has a different level of risk they're willing to accept:

1) never
2) 1/3 larger (33%) than what you calculate.
3) on the pony. I think a pony is best used and rigged like a stage bottle.

 

[Rick Murchison]

1) Within the limits of 100ft depth and NDL. When would you consider taking a pony bottle as a redundent air source? Every dive, never at those limits. something in between?

A pony is only "redundant" for the amount of gas in the pony. A 13CF pony, for example, is only "redundant" when your 80 is at 500 psi. So, in the sense that you ask the question, I never carry a pony as a "redundant" air source. I do carry a pony (minimum 30CF) sometimes, when the mood strikes me.

2) I'm resonably sure I know how to compute how much air I'd need to acend from a given depth and do a safty stop. But is there a generally accepted amount of reserve. Seems to me a 500PSI reserve is meaningless as some ponies might be 13 or 40 cu ft. Seems you'd want to measure reserve in cu ft of air at surface. (You see, I'm asking in an indirect way "how big of a bottle?") Or maybe just figure on a 15% reserve.

I generally reserve 13CF over requirements

3) Where is best place to keep the pony's regulator? Like an octo but on other side or rolled up an in a pocket?

I rig my pony like a stage bottle.

What I'm really looking to find out here is if there is a wide range of opinion or if most people are doing things the same way.

There's a wide range... there's a wide range for pony use with just me! There are those who eschew pony use entirely, and those who use 'em every dive, and there are those who, like me, keep their options open.
Rick

 

[DA Aquamaster]

Some basic questions:

1) Within the limits of 100ft depth and NDL. When would you consider taking a pony bottle as a redundent air source? Every dive, never at those limits. something in between?

The justification for apony for many divers is that a buddy may not be around when they need one and they essentially treat all dives like potential solo dives.

And a guidline for solo diving is that you should never be solo without a redundant air source deeper than twice the depth to which you can free dive. So if, for example, a diver can only manage a freedive to 15', they should use a pony on any dive deeper than 30'. This rationale would seem to be appropriate to apply to your question.

2) I'm resonably sure I know how to compute how much air I'd need to acend from a given depth and do a safty stop. But is there a generally accepted amount of reserve. Seems to me a 500PSI reserve is meaningless as some ponies might be 13 or 40 cu ft. Seems you'd want to measure reserve in cu ft of air at surface. (You see, I'm asking in an indirect way "how big of a bottle?") Or maybe just figure on a 15% reserve.?

I'd agree with Rick that you want at least 1/3 rd to 1/2 of what you think you would need to ascend safely in an emergency in reserve. I personally regard a 19 cu ft pony as the minimum size for a dive to 100'. Anything smaller may just convey a false sense of security and still leave you making an ESA. 30 cu ft is even better.

3) Where is best place to keep the pony's regulator? Like an octo but on other side or rolled up an in a pocket??

I think it depends on the kind of diving you plan to do. For a recreational diver diving with other recreational divers, possibly with randomly assigned buddies, I think staying with a conventional octo location has a lot of merit.

However, putting the pony near the octo means you have the potential to confuse the pony with the octo in a pinch. This is, in my opinon, a place where a combination octo/inflator really shines. It lets you eliminate the octo second stage, and then put pony second stage in its place. It eliminates a hose and avoids confusion and yet still provides you with an alternate second stage to access your primary tank.

Another option is to bungee the pony second stage to the pony which works great when it is carried as a stage but can be problematic when back mounting the pony. Carrying the pony like a stage is the way to go if you are more technically oriented.

You could possibly route the pony second stage around the other side, but given that you are more likely to use it than a buddy, you should use a reversible second stage where the reg can be converted to have the inlet fitting on the left side (liek the Scubapro R190 or R390) or alternatively use a more ambidexerdous design (like the Dacor Viper).

 

[Boogie711]

DA - I strongly disagree with your rationale re: Inline inflator octo's.

People choose to use a combo inflator/octo because it "eliminates a hose and avoids confusion." The argument is that it's cleaner and more streamlined, right?

But then you go and ruin that all by adding a pony bottle? Thus significantly adding cost, bulk, hoses, regulators, and confusion. No thanks.

It's a classic case of trying to compensate a skills and team awareness issue with gear selection. Personally, I always carry a pony on every dive - large enough to get two divers back to the boat safely. Which means I get someone to put it on their back and swim around with me.

 

[rab]

And a guidline for solo diving is that you should never be solo without a redundant air source deeper than twice the depth to which you can free dive. So if, for example, a diver can only manage a freedive to 15', they should use a pony on any dive deeper than 30'. This rationale would seem to be appropriate to apply to your question.

Not that I'm likely to use a pony in the near future, but this sounds like a really good guideline. The solo (and "same ocean buddy") diving I've done has been only to about 25fsw and I know that I've done a free dive (in a 6.5mm FJ, no fins) to 13ft. I guess I happened to meet this guideline. I know that I can get to 18ffw in just a bathing suit, but that's limited by the depth of the pool's dive well.

Thanks,
-Rob

 

[Lat. Adjustment]

Just to muddy the water a little more and if you are DIR don't read this. I usually dive solo or in NJ waters I just can't see him so I have a 14 cuft pony feeding my combo inflator, the BC uses less than 100psi per dive. Other than back in the days of the J-valve I have never been OOA but I have had divers low on air come to me for a breath, just make sure to give them your first so you can still control your BC.

 

[mjh]

I can just say how I use mine.

Always have it, when diving w/buddy or solo diving. Only exception is when we travel to the tropics.

I use a 30cf bottle, on a bracket, on the right side of my tank. I like having it rigged so I can reach the valve while diving. Keep my octo in the “standard” location, lower right quadrant of BC.

Lat. Adjustment: Personally I would not have my pony hooked into a duel use BC inflator. Pony = survival; when needed and I want it used solely for the purpose of getting me/buddy to the surface.

 

[RICHinNC]

see why i pm'd you ?

 

[matt_unique]

The justification for apony for many divers is that a buddy may not be around when they need one and they essentially treat all dives like potential solo dives.

And a guidline for solo diving is that you should never be solo without a redundant air source deeper than twice the depth to which you can free dive. So if, for example, a diver can only manage a freedive to 15', they should use a pony on any dive deeper than 30'. This rationale would seem to be appropriate to apply to your question.

I'd agree with Rick that you want at least 1/3 rd to 1/2 of what you think you would need to ascend safely in an emergency in reserve. I personally regard a 19 cu ft pony as the minimum size for a dive to 100'. Anything smaller may just convey a false sense of security and still leave you making an ESA. 30 cu ft is even better.

I think it depends on the kind of diving you plan to do. For a recreational diver diving with other recreational divers, possibly with randomly assigned buddies, I think staying with a conventional octo location has a lot of merit.

However, putting the pony near the octo means you have the potential to confuse the pony with the octo in a pinch. This is, in my opinon, a place where a combination octo/inflator really shines. It lets you eliminate the octo second stage, and then put pony second stage in its place. It eliminates a hose and avoids confusion and yet still provides you with an alternate second stage to access your primary tank.

Another option is to bungee the pony second stage to the pony which works great when it is carried as a stage but can be problematic when back mounting the pony. Carrying the pony like a stage is the way to go if you are more technically oriented.

You could possibly route the pony second stage around the other side, but given that you are more likely to use it than a buddy, you should use a reversible second stage where the reg can be converted to have the inlet fitting on the left side (liek the Scubapro R190 or R390) or alternatively use a more ambidexerdous design (like the Dacor Viper).

I chose never to dive with a single tank due to the obvious safety benefits of redundancy. Either I am doing a single tank with a pony or a set of doubles. Make sure you can access all your valves at all times and easily reach your regulator second stage. Make sure you use a pony for its intended purpose - to get you to the surface in case of emergency without having to rely on anyone else. Don't use it as though it is extra back gas to extend a dive.

--Matt