pony bottles

[rjack321]

I can't figure out how SAC rate (which is an aggregate measure of tidal volume and ventilations/min) interacts with "Breath Rate"??

And increasing your "breath rate" somehow decreases your total volume consumed, which is nonsense to me. Love the dual ascent rates, so realistic

If you really want a pony, go for it. I'd suggests a 13cf, but those are overkill for most argon bottles and 6cf would be a dangerous recommendation. So please, at least get a AL30 so that when you don't want it anymore it'll be useful to someone else as a deco bottle!

 

[MikeFerrara]

Ah, I follow you now. (Fortunately for me, should I ever go down that path, I've worked for the government [public schools] long enough that I have no problem following any rule set where necessary, although many of ours are far more arbitrary than the logically-derived rule-of-thirds and its ilk. )

Incidentally, Doc, you forgot the kicker:

"Never have gear failures."

(I always get hung up on that one when I'm working on planning and theoretical situations.)

I don't think that mainstream dive training does a very good job of teaching divers how to avoid trouble but...generally the methods they do teach for dealing with problems most likely to encountered (though I disagree with the priority they give them in) are adequate for those depths. ie, sharing air, buddy breathing, ESA, breathing a free flowing reg ect. I don't know of any agency that requires or even teahes students to use a pony bottle for depths in the 60 - 80 ft range in OW.

Once we start getting deeper or into overhead environments, then everyone pretty much agrees that redundancy is needed.

I don't know that you can state enything universally but I really think that most of the divers I see carrying or wanting a pony bottles are doing dives that they aren't really ready for. They're taking training and equipment appropriate for shallow easy diving and trying to apply it to something else. Maybe it's because of depth, maybe they have lousy dive buddies or whatever. I think others see the same thing which is why you see so many people recommending that you look at some other things before just adding a pony bottle to your rig. It's not that more gas is bad or that redundancy is bad. It's just that niether necessarily really solves the problem and added haphazardly and without addressing other issues (that may be more pressing), it can actually cause some problems.

I've said it before, that when I wanted a pony bottle it was because we were doing other things wrong. I didn't realize it at the time but once we addressed the other stuff, the need for a pony bottle went away permenantly. Everyone else has to decide for themselves what problem they are really trying to address with the pony bottle and if it's really effective or not.

 

[grazie42]

Originally Posted by ClayJar:
"Never have gear failures."

(I always get hung up on that one when I'm working on planning and theoretical situations.)

Everyone has a different level of risk-acceptance. What a few posters are trying to suggest (and I agree) is that if your "propability-threshold" for possible failiures is at the level of catastrophic gasloss, you have a whole bunch of other issues you should be adressing (the smart-***** in me want to quote Reefraffs mer-man example)...

There have been XXXX number of pony-bottle threads on SB and while I´ve certainly not read that many of them, none of the ones I´ve read have been caused by someone having a mechanical failiure within NDLs or a depth where a CESA is possible, with a buddy who was "switched on and ready to help" or who planned and managed their gas soundly. So if you really are concerned about gasloss, it makes far more sense to focus on those things FIRST as they are obviously far more common (though they take more than swiping a cc to correct)...

ymmv

 

[rjack321]

IMHO, its emotionally and psychologically easier and "more fun" to add gear like pony bottles than addressing the totallity of the risks ponys attempt to solve.

Like crummy buddies,
poor decision making (both on the surface and/or at depth from narcosis),
weak skills, and
fear of equipment failure (sometimes compounded by not understanding how it works, how to maintain it, how to fix it yourself and sometimes by not knowing the probability of failures)

 

[robzr]

I can't figure out how SAC rate (which is an aggregate measure of tidal volume and ventilations/min) interacts with "Breath Rate"??

And increasing your "breath rate" somehow decreases your total volume consumed, which is nonsense to me. Love the dual ascent rates, so realistic

If you really want a pony, go for it. I'd suggests a 13cf, but those are overkill for most argon bottles and 6cf would be a dangerous recommendation. So please, at least get a AL30 so that when you don't want it anymore it'll be useful to someone else as a deco bottle!

SAC/RMV and Breath Rate are two unrelated measurements, yet both play roles in calculating air consumption.... the SAC/RMV is a volumetric rate (cubic feet per minute); and Breath Rate is just how many breaths (independent of volume) you are taking per minute. To get volume of air for a given breath, you'd have to divide your SAC by your breath rate....

IE 10 cfm, at 5 breaths per minute would be 10/5 = 2 cf per breath.

Thanks for checking out the program!

regards

Rob

Oh - and the reason the volume of air will go down for an increased breath rate (given the same SAC rate) is because, during an ascent, if you take 20 breaths per minute instead of 10, each breath will be half the size (in depth compensated volume). Now since you are ascending, each time you take a breath, you are a little shallower than the last, therefore the volume as calculated at surface pressure will be slightly less.

So 20 breaths per minute at a SAC of .50 during an ascent will use less air than 10 breaths per minute, all else being equal.

 

[Nemrod]

Almost all pony threads on scubaDIRboard.com wind up with the same misguided conclusions.

1) Sport divers on singles should not be diving deep enough to need a pony and should have a buddy

Retort, some people believe in self sufficiency

2) If your diving deep you should be on doubles

Retort, doubles are heavy, impractical for travelling divers most of the time and offer no actual advantage over a pony for sport diving depths and no deco limits and non overhead diving

3)Ponys cannot get you back to the surface

Retort, ho hum, been there and done that

4)Ponys are non Guru compliant

Retort, oh well, there is more than one way to skin a cat

5) pony bottles are not redundant air supplies

Retort, then what are they?

6)The pony should never replace the octapus

Retort, the octapus is not a redundant air source--NEVER--but a pony is redundant and can serve the octapus function if so desired

7) the pony air supply should not be figured into the dive plan

Retort, hard a fast rules are to restrictive, it may be included in the same fashion as The Rule of Thirds. Neither are intended to be used but in EMERGECY, just one is in a seperate small tank and the other is included in the main supply.

It could go on forever, bottom line is think for yourself, if it makes sense, try it out and see how it works, make your own way.N

 

[b1draper]

Well, I too am a person with a pony; a 19cf to be exact. When I dive I plan my dive and dive my plan. I've only made 2 solo dives, which were in shallow water. However that's not where I've run into problems. I was faced with a CESA when I was at 65 feet and about 20 min into a dive with 6 buddies when my newly serviced regulator developed a high pressure leak which affected both second stages. The first thing I did was try to signal my buddies but all I saw were fin tips in 20 foot vis water.

My experience is that most divers don't recognize when someone else is pounding on their tank. The leak was putting off enough extra air where it kept popping my mask seal to my face by the air rushing through to my nose.

At this point I aborted the dive and made the CESA, when back on shore I was asked where I went and why I didn't stick with the group.

At that point I decided that I needed to get a pony and get comfortable with using it in an emergency. So now on my last dive of a trip I totally use my pony during my safety stop to make sure that everything is working properly and I get used to changing regs underwater. I first thought about getting a spare air but I didn't think that 6 cf would be enough if something else happened such as being entangled. If you get entangled and you have plenty of air should you need it you can focus on the task at hand getting freed.

I've realized that not everyone makes a good buddy. So I intend on planning for the worst, but hoping for the best. I don't plan on the air in my pony during my normal dive. I plan my dive and dive my plan and only plan on using the air in my primary tank. The only exception is on my last dive of the day when I practice with my pony. Before my next trip I bring my pony along when I fill my other tanks.

 

[Doc Intrepid]

...Incidentally, Doc, you forgot the kicker:

"Never have gear failures."

(I always get hung up on that one when I'm working on planning and theoretical situations.)

Clay, you're right - planning for worst case scenarios would involve gear failures.

But we're also talking (in Fire Diver's post) about newer divers. Newer divers ought not to be doing solo dives until they've gotten more experience.

Given that newer divers also are not likely in overhead environments where they cannot go straight to the surface, I'm still of the opinion that for newer divers the focus should be on getting the fundamentals down, which would be the things I mentioned.

And in the case of some sort of non-recoverable 1st stage failure, reliance on a buddy would be one of those fundamentals.

I'm not saying that sling bottles have no place ever. I don't think there are many absolutes in diving - like Nemrod said above, you need to evaluate most situations individually based on circumstances.

But for newer divers, for guys just starting out, to run out and get a pony bottle instead of making the other things second nature is - in MHO - pursuing a technological solution to a behavioral-based problem.

YMMV...

 

[MikeFerrara]

Well, I too am a person with a pony; a 19cf to be exact. When I dive I plan my dive and dive my plan. I've only made 2 solo dives, which were in shallow water. However that's not where I've run into problems. I was faced with a CESA when I was at 65 feet and about 20 min into a dive with 6 buddies when my newly serviced regulator developed a high pressure leak which affected both second stages. The first thing I did was try to signal my buddies but all I saw were fin tips in 20 foot vis water.

My experience is that most divers don't recognize when someone else is pounding on their tank. The leak was putting off enough extra air where it kept popping my mask seal to my face by the air rushing through to my nose.

At this point I aborted the dive and made the CESA, when back on shore I was asked where I went and why I didn't stick with the group.

I don't mean to pick on you but this dive is such a great example. 6 people is a herd or a flock but not a team. Break those flocks into 2 or 3 man teams. With practice they will know whether you have left or not and whether or not you need help. Dive side by side unless you are using lights for communication.

When breathing from a free flowing reg and the bubbles are floping your mask around and flooding it...First of all stay horizontal. If you need to, tilt your head so the bubbles go harmlessly up and away without causing mask trouble or obstructing your vision. There was no need to do a ESA.

Redundant air source or no, you really should learn to be confortable managing a free flowing reg.

 

[ClayJar]

Gotcha, Doc. I'll concur with you then.

I would never advise a new diver to get a pony while they still were working through the fundamentals -- weighting, buoyancy, trim, and *especially* good buddy skills. Only once the fundamentals are in place can you build on them.

(I shudder to think about what would happen if you clipped a 19cf pony to a bad buddy diving upright with no buoyancy control.)