I've decided to get a Pony Bottle; which one...?

[DandyDon]

Now, this is not a discussion on whether Pony Bottles are a good idea or not, so let's please have that one elsewhere. This is simply requested to be a discussion of which size. Thanks for your cooperation...

Looking at the various sizes, weights, and prices - based on Divers Direct, I also consider just how much air I'd get from one. A better diver might look at breathing rates, etc, but for me - it's easier to consider these as partial equivalents of a standard 80 cf tank. That is, a 6 (cubic feet) CF tank holds 7.5% as much as a 80 CF, so the equivalent (EQUIV) would be 0.075 x 3,000# = 225#. Not a lot for ascent from 100 feet or more, but better than nothing.

But let's examine a comparison, with references to how much weight increase (INCR) I'd adding to my kit or luggage over the previous size:


06 CF - 225 EQUIV - 4.2# - ---------- - $89.99
13 CF - 487 EQUIV - 7.5# = 3.3 # INCR - 104.99
19 CF - 712 EQUIV - 9.7# = 2.2 # INCR - 119.99
30 CF - 1125 EQUIV - 13.1# = 3.4 # INCR - 129.99
40 CF - 1500 EQUIV - 16.8# = 3.7 # INCR - 139.99
50 CF - 1875 EQUIV - 22.7# = 5.9 # INCR - 149.99
63 CF - 2250 EQUIV - 28.4# = 5.7 # INCR - 159.99
80 CF - 3000 EQUIV - 33.2# = 4.8 # INCR - 149.99

Anyway, this is how this ol' cowboy looks at it. If I carry a 6 CF Pony, I add 4.2# to my kit plus the Reg, SPG, and Hangar, but only get the equivalent of 225# more from a Standard 80. If I'm going to bother with a Pony, I want more than that.

For $15 more, I can get a 13 CF tank that uses the same Reg, SPG, and Hangar, and provides 487# equivalent with only 3.3# more weight.

For $15 more yet, I can get a 19 CF tank, with an equivalent of 712# more, and only a 2.2# increase in weight. I'm thinking I want at least this much for an ascent.

But for only $10 more, I can get a 30 CF tank, with 1125# equivalent with only a 3.4# increase. To me, this is more of a Stage Bottle, but if an OOA emergency ever comes up, maybe a good idea?

And bigger tanks are not that much more in cost or weight, but really - not what I had in mind.

What about a 3 CF Spare Air, with an additional 112# equivalent, or a the 6 CF Bail Out bottles with additional 487# equivalent that don't require extra Regs? Better than nothing, but not enough for me. Besides, if you fill them from a 80 CF tank that was filled to 3,000#, you're not going to get 3,000 on the Spare Air, ergo not that much equivalent!

If you were going to select a Pony for possible bailouts, which would you get?

 

[Uncle Pug]

You haven't even mentioned the dive parameters so how in the world do you expect an intelligent answer to this question: "This is simply requested to be a discussion of which size."

Ahhh... I get it... you didn't expect an intelligent answer:"this is not a discussion on whether Pony Bottles are a good idea or not"

Don neither price nor luggage considerations figure into the gas management equation. You need to think about what you will need for the dive you are going to do... or conversely plan the dive around what you have.

So.... what size pony do you need? How much gas do you need along?

 

[DandyDon]

You haven't even mentioned the dive parameters so how in the world do you expect an intelligent answer to this question: "This is simply requested to be a discussion of which size."

Yes, I started to skip this idea completely, knowing how you feel and generally post on Ponys, but - did it anyway...

 

[Uncle Pug]

But you couldn't help yourself could you?

OK... let's try to figure out what size you do need.

How much gas will you need total for the dives you typically do?

 

[pipedope]

As for me, I might just do the quick and easy pick.

If I get a 30 or 40 and rig it as a stage it can do duty as a redundant gas supply, stage bottle, deco bottle and if I get tired of shelping it on dives I can make it an emergency O2 bottle.

Then again my most common bailout bottle was an AL80. Working in shallow water it was far more than needed but it was cheap, available, and could be used for lots of other jobs also.

 

[IslandHopper]

If you simply want a redundant air source, have you considered getting a k-valve that will support dual first stages ? If all you want is a redundant regulator that would be a LOT easier than carrying around an entire bottle.
If you want a little more than an 80 gives you, then I'd get a 108 or so and a dual first stage set-up.
Now, If you are looking at deep/deco diving, then a second bottle would certainly make sense... Nitrox clean for a little added benefit ? (keep in mind that anything less than a 30cf bottle is almost useless for anything other than a direct ascent at 5 ATA)
Having only recently gotten into deco diving ... I have been using borrowed 30 ft bottles for deco mix and a 108 on my back. When I buy, I think I will get a 40 or 45 cf for my deco bottle. It's still a manageable size, and a very useful amount of gas.

Now, free advice is worth every penny you paid for it , but I find I learn a lot from these discussions... writing out these replies actually makes me THINK about what I do, and allows others to point out flaws in my thinking.

 

[MikeFerrara]

If you were going to select a Pony for possible bailouts, which would you get?

After careful analysis of the diving I do and the cost/benefit relationships I settled on a 104 cu ft poney that I back mount manifolded to my "main" tank which is also a 104 cu ft tank.

Don, the way you're looking at this doesn't make any sense to me.

Are you trying to figure out which gives you the mast gas/dollar...(al 80)...or which adds the least weight/amount of gas...of the most weight/dollar...or... :06:

 

[matt_unique]

You've already reached the logical conclusion that a pony bottle will add to the safety of your system. The decision now should be a function of your usual depths. If you are diving from shore in no more than say 70' of water a 19CF will get you to the surface safely with a stop. If you are boat diving to 130' for example, I would recommend a 30CF bottle.

If I am diving from shore for lobster for example to a max of say 50' I will use a 13CF to minimize the weight I am walking across slippery rocks. In retrospect I would not buy anything smaller than a 19CF.

--Matt

 

[MikeFerrara]

You've already reached the logical conclusion that a pony bottle will add to the safety of your system.

How can you say it's a logical conclusion when he hasn't said anything about the dives that he's doing?

It's totally illogical to assume that a little extra gas is an improvement without examining the effects of more hoses, regs, procedural options and so on have on the overall utility of the equipment configuration?

For instance I haven't ever needed a redundant gas supply on a recreational dive that I would use a single tank for. Yet if I did have a pony I would have had to manage the extra equipment on every single one of those dives.

Recently there was a thread on the board (don't remember which one) where a diver using a slung pony blew a safety/deco stop because the poney interfered with his accessing his deflator. So there are additional skill concerns.

Not long ago I read about a fatality (I think it was a fatality) where a diver simply grabbed the wrong reg and ran out of gas...or so she thought...with all those regs she didn't know which she was breathing...or not breathing as it turned out. The joy of a back mounted pony with a third reg pinned to your chest someplace.

Neither diver needed a pony yet both had problems because of it. I'm sure we could find more like them too.

If you apply logic you'll likely end up with a configuration and procedures that are clean, simple and just about fool proof. Hanging a bunch of discombobilated junk on divers doing dives within the capability of their existing equipment won't get you there.

Don,

What kind of dives are you doing and what makes you feel that you need a pony?

 

[wmspdi]

I have two pony bottles. A 19 ft3 that I use for distant travel (because it packs better) and a 30 ft3 that I use when driving to near locations. I choose the size pony I will needed based on the location and planned dive... if I feel I need the pony at all for that dive. I modified an Ultimate Pony Brackect with two cam bands (one for the main and one for the pony), instead of the cam band (for the main) and the SS clamp straps (for the pony). This way I can use the same mounting bracket with any pony when I travel. My pony reg is different from the regs on my main gas to avoid grabbing the wrong second stage.