Using a pony bottle?

[hudson]

Rock bottom must be sharable gas. Are you and your buddy otherwise capable of sharing air from your pony?

Generally speaking, unless your plan is to breathe the pony first (in which case it doesn't fit the working definition of 'pony'), it shouldn't count towards rock bottom.

Not if you separately calculate the rock bottom for yourself and for your buddy. My rock bottom is in my pony, my buddy's is in my back.

 

[bdshort]

As others have said, a pony bottle is an emergency air supply that you should never plan on using just because you want to have more bottom time. Since you're a new diver, your bottom time will increase naturally as you gain more comfort in the water and start breathing less air. If you still want more, buy a bigger tank.
By all means, get a pony bottle, just realize that it's there should something go catastrophically wrong with your main regulator. And practice using it!

I use a 30CF pony, even if I'm diving with buddies, but it definitely gives me peace of mind when I'm diving solo, which I've started to do more and more.

Talk about doubles, stages, etc. is aimed at the tech diving side of things, which if you want to get into, will be waaaaay down the road, probably. Don't worry about that stuff.

 

[spectrum]

So, you should never plan a dive where a 19cf pony is figured into your bottom time? Sorry if these questions are ridiculous, but..... Why can't you?

Of course you can if you do so intelligently without violating your safety margins. It need be no different than diving independent doubles except that the size is miss matched.

What you can't do is view it as a safety reserve and as a bottom time extender at the same time. If you are diving with a buddy and keep enough on your back to get both of you up at any time then it's all good.

On a dive where you have used it as a safety reserve you could use it on the end of the dive IF you have returned to a very safe point and want to stay in the water. I'm thinking of shore dives that end in peaceful fairly shallow coves where the ascent would be minor and a surface swim a non event.

I would not get into this without a good understanding of gas planning though.

You also do not want to use this a a crutch. If you need bigger cylinders get them. If your technique is wasting air improve it.

Pete

 

[Blackwood]

Not if you separately calculate the rock bottom for yourself and for your buddy. My rock bottom is in my pony, my buddy's is in my back.

Rock bottom is by definition a joint calculation.

Oh. I think you're saying that the half of rock bottom your buddy breathes is on your back and half the half you breathe is in your pony tank. Originally, I thought you were saying you could dig deeper into rock bottom since you have a pony.

If rock bottom is 45CF and you have a 19CF pony, the plan is broken (well... cumbersome, anyway). But I guess as long as your pony holds at least half your largest rock bottom that works.

 

[DandyDon]

Another Pony Bottle thread to fight over...!

I really have to wonder how many of the ardent posters on these threads have ever had a reg failure? They're rare but they happen, happened to me early in my diving. Or a boat buddy who fails to share their air pressure until they're at 500 psi 100 ft down; I learned better planning and buddy skills from that one, but mistakes happen to the best.

Ponies are a pain! BTW, a 19 cf tank at 3,000 psi is about 700 psi equivalent to a standard rental 80, making the 19 the obvious starting point when considering one, then add more reasons to consider other sizes. That 19 cf tank, valve, reg, spg, sling and all is an extra 15# of travel luggage, of boarding equipment, of shore diving equipment, of weight to hump up the ladder if the conditions are too rough to pass it up first, etc - and extra money to purchase, annually service, maybe even pay in airline fees. And I don't go anywhere without mine! Tomorrow it goes in for annual.

Using a pony bottle to increase any sort of bottom time is a big nono in the diving community. I would say that you could use it to practice actually using a pony during your safety stop to become familiar with deploying it. I would instead invest in a bigger tank like a 100hp or 120hp. I have a 30 cuft pony that I setup as a backup and I hope I never have to use it...

I don't, I consider mine for bailout only, but why are we so hot about the "big nono"? What about a traveling diver strapping a 80 on his back and another 80 on his sling for extended range? Some providers only have 80s. I generally rent where I can get a 100-130 back tank and sling my 19, but I don't care for the gavel pounding the "big nono".

I always dive with a pony whether solo (my normal style) or buddied up. The only exception is when I'm traveling internationally or long distances in the States. I never use the pony to extend my body time with one exception. If I'm back in the shallows (above 30 ft) and find something I just HAVE to film, I may use my pony to give me enough time to film it if my primary gas supply falls below 500 psi.

You're an exceptional diver Bill. I suppose that readers generally realize that, and but solo diving is generally an exceptional dive plan. And my buddy experiences are what got me to become a Pony toter - everywhere, which usually means removing the valve for TSA inspections at the airport. Did that the last two weekends.

Rock bottom must be sharable gas. Are you and your buddy otherwise capable of sharing air from your pony?

Generally speaking, unless your plan is to breathe the pony first (in which case it doesn't fit the working definition of 'pony'), it shouldn't count towards rock bottom.

No, Hudson had it right. If you still don't understand tho, do bring it back up.

Not if you separately calculate the rock bottom for yourself and for your buddy. My rock bottom is in my pony, my buddy's is in my back.

Essentially, that's it.

So is it okay for a new diver to consider redundant safety equipment - like a pony? Damn right! Should be required with every camera or spear gun purchase, as shooters are the worst buddies.

 

[TSandM]

jsado, you've touched off a tornado! The subject of pony bottles, and how they should be used, is a volatile one.

Especially after reading your comment about MOD, what you need is information. HERE is a good quick paper on rock bottom -- What it is, how to calculate it. HERE is a great paper on gas management. Don't feel bad that you haven't learned this stuff. It isn't taught.

What comes through clearly in your posts is that you're looking for how to get more bottom time when your dives are gas limited. This is one of the most common quests for divers who have gotten past the "How do I survive down here?" stage, and are really enjoying their underwater adventures.

The answer is twofold: You can reduce your gas consumption by becoming a more efficient diver. Getting your equipment balanced so that you can dive in a horizontal position, learing to dive with neutral buoyancy, not using your hands, and not hurrying through a dive, will reduce your gas consumption significantly. Getting someone properly weighted and balanced can sometimes reduce their gas use by 25% in a SINGLE DIVE! If you learn to be quiet and stable in the water, and make no wasted motion, and not rush, and an 80 still isn't enough gas for the dive you want to do, you need a bigger tank, not a pony bottle. Ponies come into play when you are making decisions about how or if you want to be a buddy. One of the biggest roles of dive buddies is to provide a source of gas when someone hasn't got any. If you do a lot of instabuddy diving, you may choose a pony as your own redundant gas source. You may buddy dive, but decide you would like to be able to hand off the tank to an OOA buddy rather than remain connected to them. In all cases, the pony is not used in gas planning for the dive, beyond the rock bottom requirements.

On the other hand, a larger tank allows you to subtract your rock bottom, and then the rest of the gas there is yours to allocate as required by the type of dive you are doing (see Bob's gas management article).