Ok, I'll keep the argument going just because I'm bored and feeling ornery.
For starters, we aren't really talking Newbies, first, this is also the advanced forum, the OP was asking about slinging a 13. Most people who are going to sling a pony are going to be divers who have been around a bit and are interested in committing to a more advanced rig or solo diving.
Ok, I'll grant that I didn't notice which forum it was in. But asking about pony bottles as an advance diving topic seems contradictory to me. As for anyone being interested in a more advanced rig or solo diving, he is going to know that a 13 cf pony in those situations will be as useless as tits on a bull. You want to carry a 40 or 30 or even a 19? Absolutely sling it. But a 13 as a pony is for shallow puddle splashers who are better off with it mounted on their main tank. The only thing I use my 13s for are suit inflation on very deep dives and rebreather bottles when travelling.
As far as the ease of deployment or putting it on a necklace, I like the reg bungeed to the bottle. As a stage bottle the PONY acronym would definitely apply because you need the stage gas to get to the surface safely. As a back up, if you need to share, this you can hand it off and keep your primary air.
I took the word "deployment" to mean deploying the bottle to pass to someone. That is not usually done with a "pony" and certainly not by a guppy diver. As for deploying a second stage, every newbie learns with an octo on the right chest. If the pony reg is there too, there is absolutely nothing new to learn. And as for stowing the reg by having it bungeed to the bottle, that's great for a larger stage. But I really doubt there is enough real estate on a 13 to do it effectively, and a guppy diver is not going to be able to deploy it easily, or re-stow it if it comes out.
When it comes to ease of use, a pony attached behind your back can't be said to be newbie friendly, you can't see if it has leak, you either have another SPG on a hose or you have no idea how much air it has. And if you get a line hooked over a back mounted pony, you are going to have to free yourself blind.
A newbie will not be diving solo, and a bubble check of your buddy is SOP. So much for having a leak. And after checking pressure before diving, he shouldn't care less how much air it has during the dive since there is no leak. As for a back mounted pony being an entanglement hazard, it only adds a slight amount of risk over a back mounted main tank. Think about the thousands of people still diving back mounted doubles.
I have set up my rig so that I can dive with or without the pony. Instead of an octo, I have an AIR II on my BCD and then the 13' slung on the left for when I want to solo.
Your profile doesn't list how many dives you have, but I'm betting its more than I have in mind for the kind of diver I'm referring to.
Don't forget that many of those "technical or advanced divers" will have experienced both methods (back and slung)... and decided what is optimum for them. I certainly did...
I agree completely.
Pony is an emergency resource. You should configure/carry it based on use in an emergency. There's something very flawed with justifying an approach based on not using it (which is what you've done, above).
No, I was referring to "deploying" in terms of passing it off, because that was the comment I was addressing. As I stated above, "using" the pony in a back mount configuration with the second stage on the right chest is exactly the same as what is taught in basic OW courses........ even by you
