Pony Bottle & octopus

[ChrisM]

Necessary? No

I sling a 13 cu ft pony with a second stage bungeed to the tank. Sometiems I take the pony. Sometimes I don't. Depends on dives/buddies/etc.

Main rig is a long hose and bungeed backup. Dive kelp all the time that way, no hangups, entanglements, etc.

But no, it is not necessary

 

[Colliam7]

Some very interesting ideas being presented here. I’ll add my 0.02, with the caveat that they reflect my rig, which may not be the same as the OP’s setup. For single tank rec diving, I use BP/W, with a long (7&#8217 hose and bungeed necklace; when also diving a pony (>60ft), I use an AL40 clipped to my harness and ‘slung’ on the left side.

Is it necessary to carry a traditional octopus 2nd stage off of your main tank if you also carry a 19 cu ft. pony bottle on every dive (pony has a pressure gauge)? Pony is mounted to the main tank on divers' back and is carried with the air always on.

As one respondent pointed out, you are specifically asking if it is necessary, and I agree that the answer is technically, ‘No.’ Having said that, my personal preference is that I would not eliminate my octo, irrespective of whether I have a pony. It is simply unnecessary to remove the second hose and second stage from the reg, and represents more of a deviation from a normal setup than I prefer. What if you decide you don’t want to take the pony on a particular dive? What if it leaks and empties out, and you discover that right before you are getting in the water? I guess the real question is, ‘Why even worry about these contingencies?’ Keep the octo on your reg. If you also have a pony, great. If not, no problem, mon.

As string said. My pony is my backup air source. I do not hand it off. If a buddy goes ooa he's getting my primary and I'm on the bungee back up. The pony is for if my air fails and I'm not near enough to anyone else.

I add my vote to this response. I carry a pony for me. That doesn’t mean I could not use it for a buddy, but the situation would dictate whether that occurs or not. In a buddy OOA situation, my buddy immediately gets my (long hose) primary, and I go to my necklace reg. At that point, the best approach is to keep contact with my buddy in a manner appropriate for the environment, abort the dive and get to the surface safely. If it works out that I can just give up my pony, and surface together, fine. That would not be as easy if the pony was attached to my primary tank, of course.

Could you leave your octo the way you normally carry it, and bungie the second stage for your pony to the tank, the way somebody would rig it for a stage, even no its mounted on your back??? So now you would have one in your mouth, one attached to your bc somewhere (your normal octo) and one bungied behind you.

Yes, you could do this. The primary consideration is to be sure that you can reach the second stage easily in the event you needed it. A close secondary concern is being able to actuate the valve on the tank when desired. Those concerns are what drives me to sling the bottle under my arm, rather than mounting it to my backgas tank.

The configuration raises several issues. As one respondent asked, ‘Why are you diving with a pony?’ Is it the alternate air source for your buddy in a buddy OOA? Is it a redundant air source for you in a personal OOA? Is it as a stage? An AL19 attached to your backgas certainly doesn’t qualify as a stage. If it serves as you alternate for your buddy, it is not as ‘quick’ or dependable as an octo, particularly if your’octo’ is your primary second stage (when using a necklace backup). If that is the case, consider sticking with the octo. This leaves the same choice several have already mentioned – it is redundant air for YOU.

 

[ams511]

It is a more conservative way to dive, but I am likely somewhat more risk-averse than some (or perhaps, I simply think too far).

I don't understand your point. You are trading off an additional failure point (an extra second stage) because you do not want to purchase an addiitonal pony. This is a moot point because a decent second stage is more expensive than a pony.

If your o-ring blows on the pony in dive 1 and you loose all the gas, what are you going to do in dive 2? If you have 2 ponies at least you will have a fresh tank full of gas.

With due respect, I think you need to open your mind on this issue. You are adding to your risk, not subtracting from it.

 

[divedadepths]

Yes, you could do this. The primary consideration is to be sure that you can reach the second stage easily in the event you needed it. A close secondary concern is being able to actuate the valve on the tank when desired. Those concerns are what drives me to sling the bottle under my arm, rather than mounting it to my backgas tank.

thanks. i was thinking maybe mount it valve down, and have one of those octo-bulb mouthpiece-shaped-thing-a-ma-bobs (ik tech. name, right) somehow affixed to the valve with the hose attached to the cylinder with sergical tubeing?

 

[Brand0n]

i think thats plenty safe.

 

[ClayJar]

I don't understand your point.

That much is quite obvious.

You are trading off an additional failure point (an extra second stage) because you do not want to purchase an addiitonal pony. This is a moot point because a decent second stage is more expensive than a pony.

And now I find I don't understand yours, either, as I am confused by which bits you're referring to. (Trading off what and in which direction, from where to where?)

(As to the cost of a decent second stage, both my alternates breathe quite nicely, and they both came at no additional cost when I purchased their respective primary (and first-stage) regulators. Your mooting claim is therefore itself mooted, so let's just drop that both ways and go to your main contention, eh? )

If your o-ring blows on the pony in dive 1 and you loose all the gas, what are you going to do in dive 2? If you have 2 ponies at least you will have a fresh tank full of gas.

I know, I can have a pony for each and every tank! Do I need two if I dive any doubles? Hey, and I can color code them!

In all seriousness, for one thing, my pony is DIN, and as such, is taken by me to be considerably less likely to suffer an O-ring failure and the subsequent loss of gas than yoked tanks. I carry it with the regulator charged but the valve off, so only a failure during use would cause me to lose all the gas, anyway.

If we've suffered a back gas failure at depth, and then we find ourselves unable to share the other's back gas, forcing us to call on the pony, and *then* the pony LP hose shreds itself in spite of the regular inspections (thereby losing all its gas), we'll end up buddy breathing to the surface, and there's no way in the great flames of H-E-double-hockeysticks I'm getting anywhere near the water for the rest of the day. That would be no fewer than three independent failures, and while my contingencies are planned even beyond that, it would be so far out of normal that I would not trust any of my gear until it had been properly serviced and extensively tested.

Frankly, even if I could sling two AL80s and backmount some independent 130s, I doubt I'd go back in the water. Sometimes, maybe God *is* trying to get a message to you.

With due respect, I think you need to open your mind on this issue. You are adding to your risk, not subtracting from it.

I am willing to discuss the issue (which, I trust, will be more clear to me when you explain somewhat more verbosely). Obviously, you have a case to make that goes against what I currently believe; however, I know quite well that one must never hold to beliefs too tightly, as the progress of science is often measured in eraser marks.

 

[dumpsterDiver]

If he wants to preserve the pony gas in case of a simple failure, so as to have it available on a second dive, then it would be "necessary" to have an "octo" on his back gas, as would also be the case if he wanted to deal with compounding failures. At that point, however, it becomes an internal philosophical question of why he is diving a pony.)

This argument of convieniece for a second dive seems silly. Why dive with extra gear that you don't need just so you can make a second dive after an emergency occurs on the first dive?

If you are that worried about a second dive, borrow another pony, buy another pony, buy a transfer whip, dive without a pony, or take the big "risk" of not making a second dive, but don't clutter up your gear and subject yourself to increased risk of failure by using an overly complex rig.

 

[ams511]

That much is quite obvious.

I am not the only person having difficulty with your reasoning. Please see DD's post.

And now I find I don't understand yours, either, as I am confused by which bits you're referring to. (Trading off what and in which direction, from where to where?).

You are adding an additional failure point with the addition of an second stage that is not needed. As you know seconds can malfunction. Why add another if you do not have to?

(As to the cost of a decent second stage, both my alternates breathe quite nicely, and they both came at no additional cost when I purchased their respective primary (and first-stage) regulators. Your mooting claim is therefore itself mooted, so let's just drop that both ways and go to your main contention, eh? .

My point is still valid and not mooted. You had to have acquired an additional second stage for the secondary. That money would have been better spent purchasing a second pony bottle if making the second dive is so important to you.

I know, I can have a pony for each and every tank! Do I need two if I dive any doubles? Hey, and I can color code them! .

With doubles and an isolation manifold you do not need a pony at all. You have redundancy already as long as you are able to turn off the isolation manifold.

In all seriousness, for one thing, my pony is DIN, and as such, is taken by me to be considerably less likely to suffer an O-ring failure and the subsequent loss of gas than yoked tanks. .

If you have so much faith in a DIN valve then why are your main tanks not DIN also?

I carry it with the regulator charged but the valve off, so only a failure during use would cause me to lose all the gas, anyway..

Well provided that you do not accidentally leave the valve open or it is not turned on accidentally during the dive then I agree with you. However if the second gets purged by accident you can let in salt water into the first stage. This requires a complete teardown and cleaning of the first stage.

If we've suffered a back gas failure at depth, and then we find ourselves unable to share the other's back gas, forcing us to call on the pony, and *then* the pony LP hose shreds itself in spite of the regular inspections (thereby losing all its gas), we'll end up buddy breathing to the surface, and there's no way in the great flames of H-E-double-hockeysticks I'm getting anywhere near the water for the rest of the day. That would be no fewer than three independent failures, and while my contingencies are planned even beyond that, it would be so far out of normal that I would not trust any of my gear until it had been properly serviced and extensively tested.

You seem to plan extensively for failures which is very smart. However most of you planning revolves around saving gas in the pony for a second dive. This is the part other posters and I have problems with. Would it not be much simpler to just buy another pony and when the poop hits the fan go immediately to the pony, signal your buddy and surface together?

Frankly, even if I could sling two AL80s and backmount some independent 130s, I doubt I'd go back in the water. Sometimes, maybe God *is* trying to get a message to you. .

I am not sure of the conditions in the Gulf offshore of LA or the type of diving you do but maybe this should be your primary configuration.

I am willing to discuss the issue (which, I trust, will be more clear to me when you explain somewhat more verbosely). Obviously, you have a case to make that goes against what I currently believe; however, I know quite well that one must never hold to beliefs too tightly, as the progress of science is often measured in eraser marks.

I would really like to know why you believe your configuration is superior to lets say a back mounted 30/40 CF pony with valve mounted up, valve always open, using a seperate regulator with a one primary on a bungied short hose and spg and a main tank with a 1 primary on a long hose and a SPG? Even if you do not want to purchase a second tank, you should be able to get to the surface and still have a decent reserve in the pony to make the second dive.

Clay, I am not trying to be a butthole here or start a peeing match between us. However, I believe you are better off ebaying your octo and buying another pony given your strong desire to make a second dive after an equipment failure.

 

[ClayJar]

I am not the only person having difficulty with your reasoning. Please see DD's post.

Yes, I certainly see that he is having significant difficulty understanding my reasoning. Hopefully, it will become more clear through this (two-part) post.

You are adding an additional failure point with the addition of an second stage that is not needed. As you know seconds can malfunction. Why add another if you do not have to?

If the second stage malfunctions on a dive, that is a single failure that will thumb that dive. In my diving, I consider single failures to be mere inconveniences. They are all but trivial to handle (although that is certainly not the case for everyone, for me, such is the case).

There are two basic failure modes of a second stage: Failure to provide gas on demand, and failure causing loss (i.e. depletion) of gas. The former yields results no different than diving without that second stage, and so, it is irrelevant to the analysis. The latter could be due to a ruptured hose or failed connection, but the primary case is by free flow. An uncontrollable free flow by itself is a single failure which will thumb the dive and likely precipitate an air share, however, it would pose no significant issue.

With respect to my perception of safety, then the con of diving with an additional second stage connected to your back gas is that you could have a failure causing the depletion of your back gas during an air share. The wash would be that in the event of it failing to provide gas, the additional second stage would be irrelevant. The pro would be that in the case of any single failure, you could share back gas, thereby providing an additional layer of redundancy. I consider the likelihood of a single failure much higher than that of a double failure, so it is logical for me to dive with the alternate. At the same time, I consider the consequences of a cascading multiple failure to be severe enough to merit diving with a pony as additional backup, in case there is a cascading multiple failure. The additional probability of a single failure that the additional second stage brings is acceptable to me -- in the event of a single failure, that dive is over, and I'm okay with that.

My point is still valid and not mooted. You had to have acquired an additional second stage for the secondary. That money would have been better spent purchasing a second pony bottle if making the second dive is so important to you.

Let me contest your point again, then. I was diving a single-tank rig with one first stage and two second stages since the beginning of my diving. I later added the pony in order to have redundancy. I purchased a new regulator for the pony, which came as a first and second stage. (The fact I also acquired an additional alternate second stage at that point is irrelevant.)

I do not believe there is any problem assuming that someone adding a pony to their rig will go through the very process I did. They will already have one first stage and two second stages, and they will purchase a new regulator set for the pony. Is it possible that they'll just buy a first stage? Of course it is. The in-store stock at each and every dive shop I've visited (which includes several in Louisiana, Alabama, Georgia, Florida, and even Japan) has been stongly skewed toward first- and second-stage regulators sold as sets. For example, at my nearest LDS, the only first stage regulators that do not come with a second stage are some really nice Conshelfs, which cost more than most of the bundled reg sets they sell. (Incidentally, they're bulletproof regs, those Conshelfs, and they look really nice... well, anyway.)

I know several people who have ponies, and not a single one would have had to buy an additional second stage to dive pony/primary/alternate. Please, feel free to comment on this if you have found otherwise in your experience; perhaps my experience is not typical in your locale.

With doubles and an isolation manifold you do not need a pony at all. You have redundancy already as long as you are able to turn off the isolation manifold.

I'm assuming that is your humorous counterpoint to my admittedly outlandish suggestion. In the interest of discussing just the topic at hand, I'll skip this. Doubles are, after all, not relevant to the pony bottle/octo discussion. I'll refrain from saying I'd also like a submarine, then, too.

If you have so much faith in a DIN valve then why are your main tanks not DIN also?

At first, I had typed a response simply saying that the point was irrelevant, but that would not have done justice. Let me, instead, explain why I personally consider it irrelevant to the topic at hand.

The reason I dive with an alternate second stage on my back gas regulator is to provide additional redundancy. In the event my buddy suffers catastrophic loss of their gas supply, they can share my back gas as a first option. It doesn't matter *why* they lost their back gas. They could have had a yoke face O-ring blow. Perhaps their first stage froze (causing an uncontrolled free-flow). Maybe some previously undetected contamination somehow managed to obstruct the valve's dip tube or block the first-stage's sintered filter. While some of these factors may be reduced by diving DIN, diving DIN cannot eliminate all potential failure points that could precipitate an air-share.

Converting my remaining yoke tanks to DIN would certainly reduce the chance of an O-ring extruding at depth, but that is orthogonal to the topic of having an alternate second stage on my back gas when I dive a pony. (As for the merits of converting my back gas to DIN-only, I do not personally consider the odds of multiple yoke face O-rings failing on a single dive to be high enough that such action is indicated. I do, however, change more O-rings than most divers I've been around, as I'll swap an O-ring at the first sign of age or damage -- I am not the type to dive with "just a little bubbling".)

I carry it with the regulator charged but the valve off, so only a failure during use would cause me to lose all the gas, anyway.

Well provided that you do not accidentally leave the valve open or it is not turned on accidentally during the dive then I agree with you. However if the second gets purged by accident you can let in salt water into the first stage. This requires a complete teardown and cleaning of the first stage.

I have very rigid procedures in my diving. For example, when I rock the valve knob open to charge the reg (and check the pressure), I do not remove my hand from the knob without closing the valve. That is invariant (sometimes a touch of obsessive-compulsiveness is useful, eh?). With the tank slung in front of me, it is quite unlikely that I will accidentally open the valve, especially since I clasp my hands over the first stage (it's a convenient hand-rest, and it precludes any chance of the valve impacting anything but my fingers). I also cycle the valve at certain points in the dive plan (which ensures the valve is not frozen, the reg is charged, and the pressure reading is accurate), so should it somehow be opened, it wouldn't be after the next checkpoint. (If there is a problem when I do the pony check, the dive is irrevocably thumbed.)

As to the purging, it takes around two to three seconds for a full press of the purge button to drop my charged regulator to ambient pressure with the tank valve closed. (This is related to the hose configuration of my pony reg set, of course -- diving with a button pressure gauge would yield less volume to charge and may reduce the time to ambient on an open purge, but I have not investigated that, as I don't dive that configuration.) I do not do penetration dives, and I cannot think of any case where I would have the purge button pressed against something for over two seconds.

In the interest of analyzing potential issues before they crop up in real diving, I have actually experimented with my pony to see how easily the purge could be bumped. I was, of course, thinking about the required service should it ever drop to ambient and suffer water ingress. Believe it or not, with the second stage bungied to the side of the tank, nestled against it and myself, not once in the pool or at the springs was I able to "inadvertantly" hit the purge. Is it possible? Of course it is. Do I consider it likely to have the second-stage purging long enough to drop to ambient? No, although possible, that scenario seems quite unlikely, given my experiements and experience. If I dod bump the purge, the location of the slung reg ensures I'll notice and immediately do the valve check and reg recharge procedure. (If I ever do drop the reg to ambient, however, I'll have to service the reg, but even salt water ingress through an open purge won't disable the reg. You can open the valve and breathe from it just fine, even while thinking about the inconvenience and cost you've just incurred.)

[continues]

 

[ClayJar]

[continued]

You seem to plan extensively for failures which is very smart. However most of you planning revolves around saving gas in the pony for a second dive. This is the part other posters and I have problems with. Would it not be much simpler to just buy another pony and when the poop hits the fan go immediately to the pony, signal your buddy and surface together?

I may not have fully explained everything about the sitution. I believe I can clarify.

I dive with the pony, and having a filled pony is my personal prerequisite for making a dive. I believe that is well-covered. My reasoning behind that prerequisite is that I think of the pony as an additional layer of redundancy specifically for the case where normal procedures fail (for example, a cascading multiple-failure dive which somehow precludes back-gas-sharing).

Let's say I'm out with one tank (and the pony) for a single dive with my buddy. In the event of an incident precipitating the need for an air share, we will *still* go to back-gas-sharing mode first. The pony will be reserved in case something else barges into the picture to preclude (or cut short) a normal air share. In my diving philosophy, the pony, as a completely independent system, is always kept intact as long as possible, as the reason I have it is to deal with the unforseeable.

For a rather contrived example of one case that would require the pony, if we were diving in a quarry, and my tank's neck O-ring blows, we'll share my buddy's back gas and proceed toward the exit. If, on the way to the exit, I somehow get entangled in some wire mesh that we can't seem to cut (hey, I said it was contrived), I'll go to the pony while my buddy heads to the surface for some bolt-cutters and a couple tanks.

(The odds of *that* scenario happening are quite slim, indeed, but as I said, it's only one contrived example. I'm using it only to illustrate the concept of how I look at the pony as only coming into play for *additional* problems when something has already gone pear-shaped. Another example, perhaps less entertaining, would be if one of us lost back gas and one or the other of the second stages on the other's back gas ceased to function. Again, only after a second failure would the pony come into play.)

I am not sure of the conditions in the Gulf offshore of LA or the type of diving you do but maybe this [CJ: super-tanker mode ] should be your primary configuration.

My buddy diving is non-deco diving at depths up to around 100', with no penetration or overheads. Light seas at worst, and that's only if I'm in the Gulf. In quarries, springs, and lakes, there is no appreciable wave action. A CESA is always an option, then (although it could precipitate a chamber ride, it would not likely be fatal). My gear configuration, then, serves merely to do all I believe is reasonble to reduce the likelihood I'll end up at the last option -- CESA.

I would really like to know why you believe your configuration is superior to lets say a back mounted 30/40 CF pony with valve mounted up, valve always open, using a seperate regulator with a one primary on a bungied short hose and spg and a main tank with a 1 primary on a long hose and a SPG? Even if you do not want to purchase a second tank, you should be able to get to the surface and still have a decent reserve in the pony to make the second dive.

I sling instead of back-mount so I can access the valve and see any problems that might come up. (I got a free replacement HP hose last year thanks to that, actually. It wasn't a "problem" yet, but it never had a chance to become one.) As I sling, the valve up vs. down question doesn't apply (physics and physiology pretty much declare the valve is on the end nearest your head).

I have a 19cf instead of a 30/40cf due to travel considerations. The 19cf is plenty of air to serve its purpose for my profiles (its purpose being as a next-to-last resort for a dive with cascading multiple failures). I would not be able to travel with the larger tank (darn weight/size restrictions!). For the occasional dive where a 19cf tank is not adequate for whatever reason, I just sling an AL80. It's easy enough to dive a slung 80, but it's several times what I need for my normal dives, so I prefer to go with the smaller 19cf pony wherever it is ample for the contingency plan.

As for valve open vs. reg charged but valve closed, although I consider an uncontrolled purge-to-nothing to be highly unlikely (as I said earlier), if it were to happen, I would rather suffer the inconvenience and expense of servicing the reg set than to suffer the loss of my reserve. Although I consider it a remote probability in either case, my emphasis is to preserve redundancy as long as possible, in order to have a better chance to parry the spirit of Columbo (i.e. "...one more thing...").

Regarding the single second-stage on each (the pony and back gas), that would fail to go as far as I desire in redundancy in case of cascading multiple failures on a single dive. Two tank/first stage failures will necessitate buddy breathing in either setup, but I don't weigh that as likely as a tank/first stage failure and a second stage failure. In that latter case, buddy breathing would not be required without an additional failure. It's all in perceived probabilities of failures, and as such, it becomes an optimization problem -- at one end is the guy skinny-dipping with his arms around a steel tank, and the other end flies off toward Bill Gates' fortune converted to equipment and personnel. Where on that continuum a person dives is as much a question of the person as it is of the intrinsic merits of any particular configuration.

Clay, I am not trying to be a butthole here or start a peeing match between us. However, I believe you are better off ebaying your octo and buying another pony given your strong desire to make a second dive after an equipment failure.

I don't consider your questions untoward, and while it may or may not be likely that we will agree on a single specific gear configuration, discussing such things (and our disparate perceptions of their intrinsic merits) is a perfectly reasonable pursuit. If, in the end, we can appreciate the ideas which color our perceptions, I have no doubt we will both be better for the excercise -- or at the very least, we will have thought about it far more than most.

Well, anyway, your turn.