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November 28, 2007

Pony bottles -- a good thing to have, or not?

To keep in shape I am going for a run every other morning. Religiously. I've been doing this for about five years now, without fail. I missed perhaps half a dozen runs in all of those years, and that's when I literally could not make it out of bed because of the flu or some other nastie. My run is only a couple of miles or so, but it's uphill and downhill and thus gives me a good workout. My heart and breathing rate go way up and every run hurts. No pain, no gain, I suppose. It's never easy and it never gets any easier, or at least it didn't after the first couple of weeks or so when I first took it up.

One thing I am always aware of when I run is air. Early on I determined that I was going to breathe through my nose the first part of the course and until it gets really steep. Then I remove that restriction and gulp in as much as I can. Ever since I took up scuba, I've been looking at breathing differently. I now know more about how our bodies use oxygen, why we have the urge to breathe, and the whole complex mechanism. When I run uphill -- "run" is perhaps an exaggeration; "slowly jog" is more like it -- I breathe so hard that it just doesn't seem possible that my muscles need that much oxygen, yet the urge is there. And I know that should my air be cut off, I'd instantly ... what? Die? Collapse? Pass out? I don't know, but it's hard to imagine not having air. Fortunately, that's just not an issue when you go running.

Underwater it is. No air, you're dead. That's why sharing air with your buddy is one of the first things you learn in Scuba class. Do not panic. Calmly signal your buddy, then assume the position and use the buddy's backup octopus second stage. Or you may have agreed that the buddy will use his or her integrated backup second stage, like the Scubapro AIR2 I have on my Knighthawk BC, and let the buddy use the primary that has a longer hose. If worse comes to worse and there is no secondary, you do buddy breathing where you share a single second stage on the way up. In theory those are good solutions, but I've always wondered what it might look like if you're at 80 feet with low visibility, your buddy has temporarily gone out of sight, and that is when something goes wrong with the air.

Now I know that by and large, scuba gear is extremely reliable. Things are not likely to go wrong, but there really is always something that can go wrong. Stuff can jam, break, rip, get lost, fall off, or you simply run out of air. And when you're down there, that's deadly. I've read a fair bit about cave diving, something that I'll likely never do myself but that fascinates me, and the first rule there is that everything must be redundant. Every system has a backup, and usually even the backup has a backup. That makes sense. Pretty much everything we use in life has a backup if it is really important. The brakes in a car, for example, have multiple backups.

So why does standard scuba equipment not have a backup for air? Everyone except tech and speciality divers just dives with a single tank, and should something go wrong, it's quickly finding the buddy and sharing. To my way of thinking, that's simply not a very good solution. Especially since there are ways to have backup. They are usually called "pony bottles."

Pony bottles are small air tanks with a separate regulator meant to be used in emergencies. Which makes a lot of sense to me. But from what I can tell, few people use them, and there is an amazing amount of controversy over them. Much more than I'd expect over something that seems to so sensible and logical. The primary bone of contention seems to be size.

One company that specializes in backup air is appropriately named "Spare Air." Their standard model has 3 cubic foot of air, a bit bigger than their original bottle that had just 1.7 cubic foot. The company claims that over a hundred thousand of those little mini tanks are in use. The bright yellow spare air bottles are packaged in neat systems that include mounting gear, an integrated regulator that sits on top of the bottle and does not use a hose, and a carry bag. Problem #1 is that they are not inexpensive. They cost around US$300 which is a bunch more than most big 80 cubic foot tanks. Problem #2 is that neither 1.7 nor 3.0 cubic feet of air gets you very far. The company estimates 30 and 57 breaths, based on 1.6 liters per breath. That's on the surface. Which means it's half that at only 33 feet, and a third at 66 feet. If things go bad at 66 feet, ten breaths won't help all that much, and neither does 19. And even that's assuming that you gulp in just the estimated 1.6 liters, and not a lot more as people tend to do when things go bad. Oh, and they are usually filled by connecting them to your main tank. So if you have a low pressure tank like my big old Steel 95s, then you'll get less air in the baby tanks yet as filling them to capacity assumes you start with 3000 psi.

So what about larger bottles? Pony bottles are made by many manufacturers, and they generally come in sizes between six and 40 cubic feet. They cost less, mostly because they don't come with a regulator, so you have to get one. With these pony bottles it's actually possible to bring along a fair-sized backup, enough to bail you out. But now it becomes a question of balancing the amount of backup air with the inconvenience of shlepping along a sizable second tank that needs to be mounted somewhere. A little 3 cubic foot Spare Air clips on just about anywhere on your gear. A 20 or 30 cubic foot tank, that's already another story.

Those firmly opposed to pony bottles say just that: if it's small enough to not be a bother, it's useless because it does not have enough air to be of any practical use. It simply lulls its user into a false sense of security. If it is large enough to have enough air for a serious emergency, then it is also large enough to slow you down, increase the chance of getting entangled, and just generally is a bother to lug around. So either way, they're no good and relying on your buddy makes much more sense.

Does it? I don't know. I've never been in an iffy situation, and I hope I never will. I do know that the thought of having my own backup sounds comforting. The motto of the Spare Air folks is "Because Self-Rescue is the Ultimate Buddy!" and that makes a good deal of sense. I wonder how the majority of divers feel. I rarely see anyone with a pony bottle, so perhaps most do indeed rely on their equipment and their buddies. Fortunately, I know I can rely on mine, always.

Posted by conradb212 at November 28, 2007 04:01 PM

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