Skills For Carrying And Using A Pony

[2airishuman]

I have decided to start bringing a pony tank as a safety item on certain dives. This is for protection against equipment failures. It is not to compensate for poor gas management skills, or to extend dive duration.

I have settled upon an AL19 as providing sufficient capacity for a safe ascent from the depths to which I plan to dive. I will be carrying it slung, charged, with the valve off, like a stage. Though less convenient than a back mounted pony, this greatly reduces the risk of breathing the wrong reg, simplifies fault isolation in the event of a leak somewhere, and builds skills that may be useful later.

I will be practicing skills starting in confined water next week. While an instructor will be present, he does not have extensive experience with pony tanks or stages. The skills seem straightforward, gear setup, check, enter and exit water with pony, weight, trim, practice switching regs. Anything else I should plan on coverring? Any safety precautions particular to this configuration?

 

[dumpsterDiver]

Practice entries and make sure it is clipped off well. Won't flip around and snack you in the teeth. Practice removal and replacement is harder. Other than that. Zero issues

 

[MXGratefulDiver]

.... (never mind ... I misread the post) ...

 

[Patoux01]

Yeah, again, not sure I'd want to keep one of those shut... But that's just me, I like to have air in case of trouble, without having to go and find the valve. I'm modest enough to know that when I've just breathed out fully (because that's when you'll notice there's no air coming from your main reg), I don't want to have to look for a reg and then open its valve.

Breathing the wrong tank is a non issue. There's no switching involved, nor is there toxicity.


Imo leave it open, put the reg on a necklace, and if a buddy goes OOA he gets your main, you grab the one on the necklace and up you go.

 

[wetb4igetinthewater]

I have mine mounted to my tank, but I have it upside down with the regulator hose strapped to the tank with the second stage by the handle where I could turn it on if I accidentally (did this once) forgot to do so earlier. I prefer to keep the 2nd stage out of "my way", as I feel that having it on a bungee around my neck blocks my view a bit. If I were to ever actually need it, it is easy for me to reach back and grab it. I have found with trying multiple configurations (I'm always open to ways of improving my kit, for tec though I just follow the standard)

I don't know why you'd switch to it if your buddy goes OOA. My primary tank (117 cu ft) is MUCH bigger than my 19 cu ft pony. My buddy and I can share the air off the main tank no problem. So he's getting my alternate.

 

[cashew]

This is probably covered in your "switching regs" bit, but be sure to practice deploying and stowing your hose (since you are slinging it), especially with whatever gloves you are going to be wearing.

 

[2airishuman]

Patoux01,

I'm not sure if there have been multiple accidents, or if I've heard the same account from different sources with different details, but there has been at least one death of a diver attributed to use of a pony tank. The two stories (or two versions of the same story, take your pick) I've heard are:

1) A diver lost his regulator during the course of a dive. Performing an arm sweep, he recovered what he thought was his primary regulator but what was in actual fact his pony regulator, which had not been properly secured. When the pony bottle was exhausted, an out of air emergency ensued.

2) A diver entered the water, thinking he was breathing his primary regulator but actually breathing his pony regulator. When the pony bottle was exhausted, he removed the regulator from his mouth. Thinking there was a problem with his primary air supply, he decided to switch to the pony, then correctly located and identified and tried to breath from the pony regulator.

These problems are made possible by four closely related equipment configuration choices:
a) The pony is mounted by attaching it to the primary cylinder, which can be done with any BC and minimum skill. However, it is difficult if not impossible to reach the cylinder valve during the dive.
b) Because of the difficulty reaching the valve, it is left open.
c) For simplicity, an SPG is not used on the pony.
d) Hoses for the pony and main gas supply attach to their respective 1st stages in the same area, contributing to the possibility of breathing the wrong reg.

Carrying the pony as though it were a slung stage is not possible with all BCs, and it's not as convenient, but it is much harder to mix up regs:
a) the pony reg is clipped off to the pony cylinder, making its purpose clear.
b) hoses are held in place by rubber bands or bungees and cannot be snagged during a lost reg sweep when endeavoring to recover the primary
c) because the valve is immediately accessible in this configuration, the cylinder may be carried valve off, which reduces any freeflow risk as well as reducing the risk of breathing the wrong reg. Even if carried valve on, the valve can be closed as a test if there is doubt as to which reg is being breathed.
d) An SPG can be used in this configuration if desired providing one more piece of confirming data as to what's going on.

 

[The Chairman]

If you keep it full of air, you don't have to worry about breathing on it at the wrong time. Fill it with NitrOx and you'll have to keep checking your MOD against your depth.

 

[2airishuman]

I don't know why you'd switch to it if your buddy goes OOA. My primary tank (117 cu ft) is MUCH bigger than my 19 cu ft pony. My buddy and I can share the air off the main tank no problem. So he's getting my alternate.

I believe Patoux01's configuration does not include an alternate. There is a school of thought that holds with the idea that only two secondary regulators are necessary when buddy diving with a pony tank -- the primary on back gas, and the pony regulator. I do not subscribe to this school of thought because I do not believe it fulfills the implied safety commitment that I believe I make to the other diver.

 

[scubadada]

I dive my 19 cf slung pony with the valve on, can't figure out why it would be done otherwise. I can see the reg and valve at all times, I'm not going to lose air without knowing it immediately.