Back mount pony bottle

[happy-diver]

Here it is

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Stainless steel slide for fixing a pony bottle - DIVEAVENUE

Buy/sell at the best price.With this stainless steel slide, attach a small dive tank or pony tank to your main block.

www.diveavenue.com

Here's how it goes, a 3 litre steel bottle that can supply 800 litres ish of air, high nitrox, also of deco gas

also gives you the energy to ride sharks

or you can just feed them, some fingers

To be fair, it's on your back or be square
and you don't leave home without them

 

[johndiver999]

There should absolutely never be the possibility of being surprised by an out of air situation, as in ever... Redundancy of air supply is not an excuse to ignore your tank pressure, it's important for a host of other reasons (such as 1st stage high pressure seat failure or any number of unlikely but potential gear issues...).
If there is a chance of your diving heading to more technical you'd get more longer term use with an aluminum 40 (or 30, but 40 most popular..)

So you are saying that a diver should not be surprised by a first stage failure or a hose pops? I don't understand how your comment relates to the OP's question?

 

[GiraffeMarineSalvage]

So you are saying that a diver should not be surprised by a first stage failure or a hose pops? I don't understand how your comment relates to the OP's question?

A first stage or hose failure is totally different than running completely out of air in a circumstance in which the original describes "Not sure how someone could get to that point without realizing they are low in air..."
My core point is redundancy is important but it is not an excuse for apathy of keeping track of tank pressure, gas planning, proper gear maintenance, etc, etc. and depending on future dive intentions an aluminum 40 is pretty much guaranteed to be useful both long and short term, as opposed to a smaller capacity pony bottle which might or might not be overly useful in the future. (And I will note that every tank comes with a given amount of vis/hydro overhead on top of purchase price so I would lean towards an al40, but that's simply my opinion and not to say there is anything wrong with other approaches to redundancy mentioned above...)

 

[Cthippo]

So you are saying that a diver should not be surprised by a first stage failure or a hose pops? I don't understand how your comment relates to the OP's question?

He is talking about an out of air situation, not a mechanical failure. The OP specifically mentioned OOA as a potential use case for needing a pony.

That said, IMHO the weakest link in any system is always the squishy part between the ears, and one of the primary roles of equipment is to either make it harder for us to be dumb, or to reduce the consequences of that stupidity.

 

[happy-diver]

like the mobile phone

 

[DAJ]

@tbone1004 as a purely academic exercise of ‘which is better for recreational diving’ (and assuming you can reach the valves!), it seems like mini doubles are objectively the best option.

That may depend on the system you use and the one you are most comfortable. While I have doubles for extensive work in shallow water, deeper dives, or deco dives, my single 130 is set up a bit different than most and gives me plenty of redundancy. As I sling a 40, I dive with three first stages, three second stages, and two independent air sources. I double or triple up on many things as much of my diving over the years has been solo, even when you have a support team topside. I run the same setup whether working or recreational so it’s second nature. When I use a dry suit, none of the setup really changes as I use a separate argon bottle for suit inflation that connects to the left side of my back plate. Some have seen this but here is my single 130:

 

[happy-diver]

I would send the robot and go diving instead

 

[SlugLife]

I'm considering setting one up. The only time I used one was when we were using surface supplied air, and thankfully never needed it. So here's my though process.

Worse case is I suck a tank dry. Not sure how someone could get to that point without realizing they are low in air, but it's worse case. If that happened, the octo on my main tank is not going do anyone any good. Me or a buddy. No air to breathe, inflate the wing or the drysuit. That's what's called a bad day.

More likely case is that I find myself low on air. At this point there is still enough to inflate the wing and drysuit but maybe not enough to get to the surface safely.

So considering the more likely scenario, I'm thinking a back mounted 19cu pony with it's own 1st and 2nd stage. Maintain the octo I currently have because I wont always need a pony bottle. That will give the breathing air I need while using what's left in the main tank for wing and drysuit inflation. The assumption is that if I ever needed to use alternate air, the dive is over. Maybe hang the pony 2nd stage on a necklace.

Does this idea hold water? I would also likely be in a FFM if that matters. I don't really dive solo anymore, but even on group dives there are many instances where I might venture away from the group. Far enough away that should something go wrong, I may not make it to a buddy's octo.

• Actual worst-case is more likely some kind of regulator failure, such as a hose-leak, o-ring-blows, etc. I've experienced this (loose hose), and the bubbles are disorientating.
• If you're relatively neutral (or even a little negative), you shouldn't need to inflate to surface. As you fin up, your BCD (and dry-suit) will inflate further, meaning you'll be dumping air from your BCD, not adding it. You can also orally inflate, while using your pony.
• 19cu is a fantastic size! (more here on pony-sizes)
• I definitely recommend a completely separate 1st and 2nd stage. Your octo can become the 2nd stage for your pony-bottle.
• I'm a big fan of using necklaces, clips, or regulator-retainers of some sort. Your regulator should ideally always be where you can find it quickly and easily by feel alone.
• Yes, your dive is over if you ever need to switch to the pony.

"I would also likely be in a FFM if that matters."

I recommend all divers take a couple practice-breaths from your pony or octo every dive during the dive. I have no FFM experience, and this might be more annoying to do, but perhaps worth doing anyway.

The combination of FFM, buddy-diving, and regulator-necklace does introduce one issue. How do you air-share? You can use a regulator necklace, but you need to be able to remove the regulator from the necklace.

Dive Rite Regulator Necklace

The Dive Rite Regulator Necklace made from standard { 3/16 in | 0.48 cm } bungee and the opening for the mouthpiece is adjustable. The necklace is perfectly designed to fit around a diver's neck, with or without a hood, keeping your auxiliary air source close.

www.divegearexpress.com

Something like this would probably work, although you can probably do the same with paracord and 2 prusik-knots.

The rubbery silicone necklaces also work, but I find those necklaces annoying.

I don't really dive solo anymore, but even on group dives there are many instances where I might venture away from the group.

There are many instances where one might effectively become a solo-diver, even without the above.

 

[SlugLife]

I was thinking SPG mounted directly to the pony 1st stage to avoid yet another dangling hose.

You can use a mini-button-SPG (thye cost about $15). However, you can also have a HP hose just slightly shorter than your regulator-hose, and wrap the two hoses together using the spiral-wire-protector material (random example). I don't have a photo (because I dive sidemount), but I've seen some other divers on ScubaBoard do that.

 

[SlugLife]

I know quite a few divers around here that leave their larger ponies on shore because a 30/40 gets cumbersome. The back mounted 13/19 is always there and as a result more reliable for training and what is ifs.

I've noticed a similar phemomenon, and written about it before.

30cu or 40cu - More air is always good. However "the 13cu on your person, is better than the 40cu you left at home." The problem I've noticed with larger sizes, is that divers get lazy. Most divers seem to leave their 30/40cu tanks at home or on the boat. Some divers claim they don't mind that size, but I'm just reporting what I observe.