Do I want a Spare Air

[Angelo Farina]

Although I own a 3-liters aluminium pony bottle, I do not like carrying it with me most of the time.
Indeed it had been great fun for my children, who learned using it in the swimming pool when they were around 2.5 - 3 years old...
I tend to calibrate my additional air supply depending on the depth and duration of the dive.
For shallow dive (15 meters max) I do not have any redundant supply, and I use a single reg with octo.
15 to 30 meters, but still within NDL, I use a tank with two independent posts, two fully independent regulators, and a mechanical reserve giving me 50 bars of additional air, if needed.
When I was younger I was going deeper, up to 50m (the maximum depth I am certified for) and with some not-very-long deco. For those dives I did use a 10l+10l back mounted twin tank, of course with two independent regs.
I did add the pony tank just in a few cases, when I exceeded those limits and adventured in the territory which, at the time, was called "deep diving" (there was no "tech" yet - and 50m was "normal", not "deep"). So a twin set on the back, plus a side mounted pony, 3 regs in total. A pony of less than 3 liters is substantially useless, in my opinion.
Last time I did such a deep dive was probably around 1985. I did never certify for those deep dives, nor I loved them particularly...
At 60m I was always quite narced!

 

[Divin'Papaw]

One thing to keep in mind. I only see them occasionally on charters down here in South FL. Almost exclusively when one of the guests on the boat shows up with one the boat crew know that this may be "that guy/gal" and they watch them more closely than the other guests. A Spare Air is just not a serious piece of equipment for a diver. I put it in the "useless crap" column that for some reason just doesn't seem to die. Clearly they sell enough of these to make enough of a profit to continue to sell them but I'm just not sure how.

 

[broncobowsher]

As stated above, don't waste your money. 70-90 feet of water doesn't make gear any less reliable.

 

[James79]

Despite all the hate people here have for them, make your own decision. In that decision, ask yourself some questions, and make realistic assumptions. Some things to think about, for sizing any independent alternate air supply (not just spare air):

1. Why do you think it will help? (to get to surface, to get to buddy, to solve a problem?)
2. Is it sufficient gas for item 1?
3. Is the need better served by a skill/mentality solution (better buddy awareness, better gas management)?
4. Will it actually be carried regularly?
5. Will it be practiced with regularly?
6. Is it cost effective?

One viewpoint is that any air is better than no air, i.e. spare air giving you one or two breaths on a CESA versus potentially none. Others say it is a false sense of security. Both are valid views, depending on YOUR mentality and views toward it. As someone who has trained with a version of spare air for aircraft egress, I have a muscle memory for it that lead me to set up my 19cf pony in a similar fashion... and I still practice deploying and using it. I don't, however, always carry it.... it is one more thing to deal with gearing up. Where as a spare air type can be harness mounted and is just a part of your BC (easy to keep carrying).

Regarding reliability of gear... Modern gear is stupid reliable, and designed to fail "safe" in the event of a failure. Simply put there are few failure modes that won't continue giving you air in some fashion. Even if you blow a hose, you will most likely be able to ascend at a reasonable rate (omitting a safety stop) and make the surface prior to running out of air.

Of course, my advice is worth what you paid for it! lol

Respectfully,

James

 

[scubadada]

short answer no.
long answer, you don't want a pony bottle either. You want to plan your dive properly so you don't have to worry about such things.
If you are not going to want to rely on a buddy, then there are other options out there for proper redundant air, but I don't think pony bottles are the answer and a spare air certainly isn't.

Hi @tbone1004

I'm interested in what you mean in your post, please describe in more detail. Specifically, what are the other options out there for proper redundant air and why is a pony bottle not the answer?

Keep in mind that this is a relatively new sport diver, I'm assuming doing no stop dives, with or without a reliable buddy, who simply wants backup gas should something go awry. @Kevin Donlon can correct me if this is wrong.

However, this could be expanded to somewhat more adventuresome diving. Take a diver using single cylinder backmount and an appropriately sized pony for solo diving, generally within rec limits, often closely approaching NDL or doing limited backgas deco, say <10 minutes. This diver is not interested in switching to sidemount or backmount doubles. What is the better choice over a pony?

Thanks

 

[tbone1004]

@scubadada
complicated...
Since we are in the basic forum, that means we aren't talking about solo diving. In the paradigm of basic open water diving, your buddy is your redundancy. Why redundant regulators, tanks, bottom timers/computers, etc. are not required. Yours fails, you use your buddies. If that's the case, then you don't need any redundant gas supply. If we are talking unreliable buddies, then this is no longer about basic scuba diving and is about solo diving whether you like it or not, unreliable buddies make you a solo diver.
If we talk about solo diving, then the discussion changes. We talk about solo diving as requiring redundancy in gas supplies, however instructors are always solo diving, yet no redundancy is required at the open water level. Why is that? Theoretically it is adequate planning. I'll be solo diving to 100ft on Saturday and will be in a backmounted single. I know that I can make a direct ascent, I know I can freedive to 100ft with no issues, but I also know that unless I properly run out of gas, there's really no regulator failure that will suddenly stop my ability to breathe. It may make breathing annoying or really exciting depending on the failure, but it's not going to stop the flow of gas.

If I'm solo diving in the ocean to 100ft, then I wear doubles because I find them to be less irritating than dealing with some sort of slung stage/bailout/pony bottle. If in fact they really don't want to, then get a real bottle that's useful and can allow you to make a "normal" ascent instead of a direct ascent, and for that, I truly believe an AL40 is as small as you want to go at 4ata's.

 

[wstorms]

like said before it's important to know how you want to use your extra gas and when.
For me, when I consider the bang for the buck, and having to add an extra item anyway, I want to make sure it can actually help me out of the widest but still realistic variety of WSHTF scenarios as possible. Worst case, say an advanced rec diver with a deep dive specialty goes to 40 meter (5 ata) but stays in NDL limits. Something goes wrong and you need to switch to your alternate gas supply. Now consider it takes you 1 minute to resolve the immediate problem, refocus and start your ascent. If you ascent with 10 meter (+/-3feet) / minute it will take 4 minutes to reach the surface. If you add a safetystop (mandatory according to the PADI RDP) you will add 3 minutes more.

We are talking about 5 minutes at an depth of 3 ata and an additional 3 minutes at about 1.5 ata.
If you assume your SAC rate is about 30 liter / minute under stress, this means you will need
5 x 3 x 30 = 450 liter for the ascent
3 x 1.5 x 30 = 135 liter for the safetystop

in total 585 liter of free gas for the fastest ascent still considered safe and this is assuming you stay relatively cool. In reality your gas consumption goes up enormously under stress, so 30 liter per minute might be underestimating the actual use.
585 liter is 21 cuft and then you suck the bottle dry...
Add a little bit extra and typical pony sizes don't really make that much sense anymore compared to an 40 cuft alu stage.

@mods I was too far into this post to abandon it, but as tbone pointed out this might not be suitable for the basic forum, feel free to mod / remove if needed

 

[woodcarver]

I am soliciting opinions on carrying a Spate Air secondary air source for emergencies. I am a relatively new diver that is starting to dive down 70 to 90 feet. My primary fear is equipment failure and needing to rely on a buddy. How common are equipment failures at depth? Is the Spare Air a good option for deeper dives?

You've probably noticed a lot, the majority of those who reply anyway, seem to have a very negative view of the Spare Air. I am of the opinion that any air is better than no air. A lot of those who poo-poo the SA system probably aren't aware it's available in a 6cu size now either, as demonstrated by some posts.
Is a SA ideal? No, but it's easy to travel with and easy to sling, and easy to use. All of which make it a helluva lot more practical than a 19cu+ pony. I carried a 3cu SA for several years figuring if the SHTF I would rather have a few extra breaths on my way to the surface. Will it provide enough air to bring you up from 100'-130' and do a safety stop? No. But it will get you up to where you might only have to do a CESA from 20'-30' instead of 100'+. And by definition, the safety stop is an extra, recommended, not required, part of recreational diving.
Nowadays, I pack a 13cu or a 6cu pony, with an H2Odyssey reg, depending on the weight limit available after the GF throws in all her stuff. These sizes are realistic to travel with. If SA had the 6cu option a few years ago, I would probably still be carrying the SA. I like it's simplicity.
Because it is available in a 6cu option, make that your minimum option. And learn about air consumption. Understand the limitations of a small pony at depth and practice using it. No pony is worth carrying if you don't know how to use it.

Now I will prepare myself for the usual flaming of someone who actually recommended a Spare Air.

 

[Protondecay123]

I would say if you are going for redundant air go for a 30cf or 40cf with redundant 1st and 2nd stage, and stay way from Spare Air cans due to marginal volume of air. They may be just enough to make it from 100 fsw, but if there is any complication then its much more questionable. That's just me though, YMMV.

 

[broncobowsher]

6 cubic foot spare air?

Dive Gear Express sells a 6 cubic foot bottle with a valve. Add a basic 1st and 2nd stage regulator and a button pressure gauge. A spare air that actually breaths as good as a regulator. Later it can be cannibalized and all the parts will be useful at a later time.

I know one person who has a small pony bottle they always travel with, it is a 13 foot. Don't think it has ever been used in the decade I've known him. But it is his insurance policy. Just the way he is.

I got a used spare air once. Breathed like crap. Only used as a pool toy.