Rec Diving a Pony

[Bowers]

I read the first few pages then got bored...
my 2psi is that it is acceptable to loose the back gas octo when a pony second stage is available. However i am one of the guys who leave my primary setup alone and simply add a “sidemounted” pony when i feel its called for. I leave the pony charged but off and the reg stowed in the bungee just like a deco or stage bottle would be. I handle sharing air like i would on a single tank (i plan my dives without figuring in a pony) and the pony is for my self reliance if i have a failure that cant be easily overcome.
Like others have pointed out, doubles are better (i love diving sidemount) but when im teaching advanced recreational classes, the pony is a quick teach for my students and take up less space, making them more practical for the rec diver just starting to expand there horizons/become more self reliant.

 

[-JD-]

As an example of an especially bad configuration seen in the wild.

FFM on primary tank, long hose on primary tank (for buddy or yourself). Pony bottle with clipped off 2nd stage. 2x 1st stages and 3x second stages. Now its not unheard of for a 1st stage to fail or become blocked with debris. If that happens to the primary tank's 1st stage, you are ditching the FFM to change to another reg. But of course you are doing this in anger and can't exactly see, and if in frigid water have a abrupt mammalian instinct to breath too. The pressure gauge still shows that the main tank has gas in it (if you can see that) but you've got to fumble between 2nd stages half blind. Pick the wrong one and by the time you sort it out drowning is a distinct possibility. I know tbone knows this, but its just one example where more is not actually helpful.

Pony reg goes on a necklace (or stowed if a slung-bottle) and THAT is where one should be going if air delivery stops on the primary. Neither of those locations is where the stowed/clipped-off LH reg is. The target reg should also be identified (deployed if required) and test-purged before removing the FFM so as to minimize the chance of MDR-sucking water. Then do troubleshooting on the main gas system if able.
I do believe that in this case you are attributing an equipment cause for a skills problem ...

 

[johndiver999]

The extra hose and second stage is a potential failure point. However, it causes a small increase in the chance of a failure.

The consequences of such a failure - when diving with an independent pony bottle are, however quite small. In other words, If the (presumably, unnecessary) octopus hose explodes, you just switch to the pony and go up. It ain’t really that likely and if it occurs, it still isn’t going to hurt anybody. These are the kind of risks I don’t worry about too much (low frequency of occurrence and little to no consequences).

On the other hand, the assertion that the second stage adds complexity and could result in confusion IS a big freaking deal. Getting the second stages mixed up and getting confused as to what tank you are using, could (and has) killed people. So I would weight this aspect much higher.

If the diver is using a slung pony and the second stage is secured like a stage bottle and secured to the tank, there is essentially zero chance they could start using that second stage on accident.

However, if the diver back mounts the pony and decides to rig three second stages, none of which he can easily, visually verify the connections, then that is a situation where the third second stage becomes important in my mind.

Getting the regulators mixed up, can have deadly consequences and the overall risk profile might actually be worse to carry three second stages that could be confused versus not using a pony bottle at all.

 

[James79]

If the diver is using a slung pony and the second stage is secured like a stage bottle and secured to the tank, there is essentially zero chance they could start using that second stage on accident.

However, if the diver back mounts the pony and decides to rig three second stages, none of which he can easily, visually verify the connections, then that is a situation where the third second stage becomes important in my mind.

This is a distinction that makes all the difference. Out of curiosity, does anyone advocating no main tank octo with a pony know of a case of second stage confusion when the pony is slung with the second stage stowed on the bottle? I claim no expansive knowledge on it, but the ones I have heard of (reg confusion incidents with a pony) are all with the pony tank mounted.

Respectfully,

James

 

[Edward3c]

This is a distinction that makes all the difference. Out of curiosity, does anyone advocating no main tank octo with a pony know of a case of second stage confusion when the pony is slung with the second stage stowed on the bottle? I claim no expansive knowledge on it, but the ones I have heard of (reg confusion incidents with a pony) are all with the pony tank mounted.

Respectfully,

James

In the early days of pony use there were a few near misses (and fatalities) of the diver starting the dive with the pony reg. when the pony ran dry they bolted for the surface or tried to find their buddy. At no time did they use either reg from their main cylinder.

The root cause was diving the configuration without training. Their old memory muscle took over.