A couple pony questions

[mikemill]

Preface: Not going to start soloing yet but wanted some more information as I prepare for it.

I'm looking at getting a pony as a bail out bottle and I wanted to get your opinions.

First: Sling vs mounting. I foresee myself soloing mostly for photography (admittedly I've already push/skipped the buddy/solo line a few times while taking pictures). For this I just see a slung pony getting in the way. Now I also foresee doing a lot of these dives from a boat so the possibility of random_ooa_diver_666 coming up to me isn't insignificant. Is there a way to get the best of both worlds?

Pony size: For this I broke out a bit of math (and a spreadsheet). I can see myself going to 80+ feet on a boat dive. So figuring a 100 ft dive, 1.0 SAC due to "oh ****", 60 ft/min ascent, and 5 minutes at depth to deal with any issues I got 27.73 cuft. Does this seem reasonable? Using this number should I get a 30 cuft or 40 cuft pony? I'm kinda leaning towards the 30 as 100' shouldn't be that regular of an occurance and by going 10' shallowed it cuts it down to 24.77 cuft needed.


Thanks all.

 

[shoredivr]

Mounting a 30 cuft wouldn't be my first choice.

If you can, why not rent or borrow a 30 or 40 and try diving it? I sling my 30 and don't notice it being any kind of impediment to hovering close to a shipwreck or the bottom.

 

[Kevrumbo]

Minimum 19 cuft pony recommended . . .prep, assemble and sling it like like a deco bottle.

 

[FritzCat66]

I also debated between a 13cf, a 19cf, and a 30cf pony, and how to mount/carry it, for pretty much the same reasons you mention: I'm into photography and thus often find myself solo, typically less than 100' depth, no overhead, no deco, etc.

Luckily, I have some techie dive pals who were willing to lend me some of their gear to test out, so I tried several different combinations.

Ultimately, I went with the 19cf, and I use it "bagged", i.e. attached to my primary tank yet removable underwater if necessary (with a little practice). The sling simply didn't work for me and I often found it just "in the way", even with the little 13cf.

Your calculations are right, and I looked at that same scenario: for the 1.0 SAC rate and 5 minutes "problem time" at 100', the 19 isn't going to quite give you enough (and the 13 is just too small). However, the 30 was just a bit too big and for anything shy of my "worst case" scenario, the 19 is fine and much more portable. And if I do run into that worst-case scenario, well... I guess there goes my safety stop, but hey that's why they call it a recreational no-deco dive, right? Because even in that scenario I can do a controlled ascent.

Another problem with the 30 is that I found it difficult to setup on most Florida dive boats due to the way the tanks are usually secured to the boat - it just doesn't fit in the usual rack, especially on a full/crowded boat. The 19 is sometimes still a problem in that regard (especially if they have those darned tubes), but usually fits just fine.

It's a calculated risk, and thus entirely up to you. If at all possible, try out some different ponies and pony mounting/carrying options before you get yours. Because that's only part of the decision, there's a whole 'nuther set to make: if mounted, left or right side, valve-up or valve-down? What kind of valve/1st stage/2nd stage? Second stage necklaced, bungied to pony, or where? Standard SPG, mini-SPG button, or no SPG? Always filled with your backgas or just plain air? Valve open or closed during the dive? You'll find folks here with any combination of those, and for myriad reasons.

Since we're solo, we're mostly just interested in saving our own a** with the pony, so the driving thing behind my decisions on all those is what works most intuitively for me, because the way I look at it I just want my pony to be a regular part of my gear that I use the same way every single dive no matter what so it's always there, and that's what I ended up with.

>*< Fritz

P.S. The pony config I ended up with, just for the record: 19cf Luxfer, Zeagle Razor combo valve/reg, 36" Miflex hose, bag-mounted to tank on left, valve-up, valve-on, with hose routed under left arm to necklaced XS Scuba Airwave reg - which lies flat and has a left-hand hose mount, a button SPG and LP overpressure valve mounted to valve/reg, and filled with air only.

 

[irishsquid]

...I'm looking at getting a pony as a bail out bottle and I wanted to get your opinions.

First: Sling vs mounting. I foresee myself soloing mostly for photography ...For this I just see a slung pony getting in the way.
Pony size: ...Using this number should I get a 30 cuft or 40 cuft pony? I'm kinda leaning towards the 30 as 100' shouldn't be that regular of an occurance and by going 10' shallowed it cuts it down to 24.77 cuft needed.

Thanks all.

Sling it. I'm not a Photographer, but I could imagine the Pony being a nice stable platform. I was deciding between a 30 and a 40. There was zero difference IMHO between them that I could notice, so I went with the 40. Extra air and a great stage bottle for later on.

Mounting a 30 cuft wouldn't be my first choice.

If you can, why not rent or borrow a 30 or 40 and try diving it? I sling my 30 and don't notice it being any kind of impediment to hovering close to a shipwreck or the bottom.

Yep!

 

[dave4868]

Your calculations on size make sense. It appears a 30cf will meet your needs.

I suppose a slung pony might create only an occasional minor hindrance to camera use. Nevertheless, I mount my al30 to my hp120 and it's definitely out of the way when I'm going for low perspective shots or swimming and panning shots, etc. Besides, I often have other things in front, like a flag line handle, a hand spear, etc. My dives often become multipurpose dives. That might be a consideration if yours are also.

Dave C

 

[spectrum]

Here's an example.

I'll say that my slung 19 pretty much disappears.

 

[dumpsterDiver]

Do you really need that much time on the bottom to solve a problem? Do you really think that you are going to simulataneously have a catastrophic total scuba failure AND get tangled in the bottom at the same time while solo taking pictures? To me, that is too unlikley and I will accept the "danger" of a smaller pony for the convienece of a lighter rig.

I own a 6, 13 and 30 cu-ft bottles. I am comfortable using the 6 to 100 feet and the 13 to past 130 feet, but I understand that I must leave the bottom ASAP with those bottles and depths.

I back mount the bottles, but use the 30 as a stage bottle for deco. It is much cleaner to have it back mounted. The problem with the 30 is that it becomes heavy and a pain to carry and many people just stop carrying them (in the water they are not a problem, rather they become a pain on a rocking boat).

I recommend a 13 or a 19 for diving in 90 feet solo, no deco, open water. In a real emergency, you can probably risk ascending at 60 feet per minute and within one minute you should be near 30 feet, you can then chill out and control your ascent. A 13 (or even a 6) will take care of that type of scenario.


Slinging a bottle is a little safer, but is a pain on many Bc's, but works fine on a BP/W. It DOES get in my way there. you need to try to make rational decisions about levels of safety versus convience.

Doing the math and determining how much time you want to be able to spend on the bottom after a total scuba failure is an excellent place to start and should allow you to pick a bottle you can live with.

You should also consider multiple dives and if you do not have a whip to top off your pony between dives, even a small leak during a dive could cause you to loose 300-500 psi on a pony and when you start doing dives with a pony only 2/3 filled because you forgot to turn the pony off during the surface interval, a bigger bottle 2/3 filled is better than a small one. However, a 40 cu-ft pony is ridiculous for an 80 ft dive.

 

[FritzCat66]

You should also consider multiple dives and if you do not have a whip to top off your pony between dives, even a small leak during a dive could cause you to loose 300-500 psi on a pony and when you start doing dives with a pony only 2/3 filled because you forgot to turn the pony off during the surface interval, a bigger bottle 2/3 filled is better than a small one.

A good reason to consider a transfill adaptor for whatever kind of pony you get, but especially for the smaller ones (13 & 19). Just turning on the valve to check pressure and/or charging the line several times over a few days' diving will cause a noticeable decrease in pressure (and therefore volume).

No use having a spare tire in your car if it's flat, ya know?

>*< Fritz

P.S. Those line charges at depth are also why it's worth considering an LP OPV for your pony's first stage as well, although of course as with everything pony-related some will disagree. Ponies are wonderfully ideosyncratic, as you can tell by all these responses! Try as many options as you can before purchasing.

 

[pdelannoy]

I solo dive with a mounted 19 with its own dedicated regulator and spg.