Pony Bottles

I would like to do some solo diving this summer, and I think I should invest in a practical alternate air source. I'm at the instructor level, but not a technical diver. When I google pony bottles, this seems to be the most popular choice: Spare Air Package 3.0 Cubic Foot

1. Has anyone used this system with a large camera in-hand, and how was it?

2. Is there another system that's preferable? I'm open to suggestions.

3. Or, should I just stay shallow, and practice my emergency ascents?

Thanks for your help.

--David

I would like to do some solo diving this summer, and I think I should invest in a practical alternate air source. I'm at the instructor level, but not a technical diver. When I google pony bottles, this seems to be the most popular choice: Spare Air Package 3.0 Cubic Foot

 

1. Has anyone used this system with a large camera in-hand, and how was it?

 

2. Is there is another system that's preferable? I'm open to suggestions.

 

3. Or, should I just stay shallow, and practice my emergency ascents?

 

Thanks for your help.

 

--David

Personally I feel that 3CUFt is not enough air to be truly useful.

I would look at a 10-13 CUFt bottle myself.

Of course there is significant dispute/discussion on the issue of a "bailout" or "pony" bottle.

If you want a redundant air source then 3L 232Bar is probably about the minimum that is of any use as long as you are not clocking deco.

Get the ally over the steel cylinder type - it won't be neutral in the water as it is not big enough to cover the weight of the regs but it will be better than steel. You can make 7L ally's neutral if you add enough helium!

By the way this whole subject is probably as contentious as Canon vs Nikon

Pauc C

I agree with Mark, a Spare Air will do little more than help with a pretty rapid emergency ascent, and not with unplanned deco etc I don't think anyone can argue against having a 9-13 cu ft pony bottle (mine is 11 I think) except of course providing a false sense of security. The best way to carry a pony is with it clamped to the side of your main tank, that way it's out of the way and should not interfere with your photography or any other aspect of your dive.

For 25 metres plus I often use a 3 litre 300 bar steel (Faber) pony, side slung like a stage. Yup, its heavy, so I take some lead out of my pouches...

I fill with 36% which gives a MOD of 33 and a bit (1.6), but if I found myself sucking on it I'm only headed one way and quite quickly. I don't s'pose I'd get an O2 hit on half a dozen breaths the deep side of 33...

One day, I'll run a dummy emergency ascent from say 35 metres and see how much gas I use, with a stop thrown in too.

First of all you should get yourself knowledgeable in self rescue skills. Even though I'm not a big fan of PADI, the PADI rescue course if the best that you'll ever do! Any of the other training agency's will train you in these skills at some level or other.

I wouldn't go for one of these tiny pony's, you only get a few breaths out of it and at any depth and you'd feel your tank starting to become hard to breath from if it was getting seriously low on air. You'd be better off going for a larger tank at least 3litre capacity!

I would recommend a 13 cfm ( or bigger ) tank ran as a completely redundant system.

In a perfect world it would be filled with 32% nitrox - this mix is perfect for emergency deco or ascents.

This is the minimum that would be acceptable to me for solo diving in a commercial environment.

Privately I would be looking for a bigger safety margin if I was doing real solo dives.

A big breath and...

... a SpareAir is a gimmick that might get you up from the bottom of a deep swimming pool. It won't support a typical 3-minute safety stop for the average diver. I think a 3l/25cub. foot is the minimum. 232 bar steel is durable, and you just wear less weight (an ally floats when ampty, which is off-putting on your safety stop). I only use a 300 bar for oxygen-rich final deco. mixes. You can put a 3l cylinder alongside your main, or side-mount it without being unbalanced.

What I normally do is wear twin manifolded 7l 300 bar steels in the UK, with twin regs. Very well balanced for photography.

Abroad is a problem: the TSA have taken to stealing pony cylinders, and they are very rarely available for hire.

Tim

B)

Have you guys really ever used a SpareAir 3cf? You do need to realize its faults and benefits. First of all, its not meant for deep diving or deco or wreck penetration or caves, etc. If that is your thing, then you are correct, a much larger pony bottle is needed and the SpareAir is just a piece of trash hanging from your BC getting in the way. For most recreational diving, above 75 - 60 fsw (a generalization, I know), the SpareAir will provide about 60 full breaths. Next time you are ascending, try to count your breaths to the surface from this depth. I think it will come close to 60. You may not have time for a proper "safety stop", but since you switched to your SpareAir, this is an emergency. That little bit of extra air could mean the difference between a panicked, drop your weights, emergent, buoyant ascent and a controlled emergent ascent.

Not a popular view, but it holds true for myself and others I know using a SpareAir. If I deserve a flame, so be it, but it does provide me with a piece of mind that if I have a regulator malfunction at 60 fsw and I'm diving alone taking pictures, I can still make it to the surface safely. Just know the limits of your equipment.

SpareAir is better than no air but...

In a perfect world I'd be diving a small set of doubles with isolated manifolds using 32% and running my computer on air settings.

Unfortunately, that isn't possible most places I dive so basically more air is better air.

If 3CuFt helps you stay alive then OK but as has been mentioned earlier this is a pretty contentious issue.

Here is a question for you: do you know your max 02 consumption rate at the surface?

Here is what I know about mine (mind you this is absolutely Max)

Feel free to correct my calcs since I did them in a hurry

If my heart rate is topped out my Max 02 consumption is 46.8 ml/Kg/min

Now I weigh 70Kg so at 32% mix 1 CuFt will last me about 25 seconds

So, the 3CuFt tank would last me all of one minute.

Now, hopefully I'm not maxed out heartrate wise, but one must also then account for the consumption rate at depth.

Trust me, if you do run out of air at depth, your heart rate will most probably skyrocket and so will your breathing rate.

just get an AL19 with a simple reliable reg and a button spg - either slung(in the way for photog) or attached to your primary cylinder with the reg over your shoulder. That should get you to the surface from 100', but I would probably not go that deep solo with that configuration. Then you have a "real" set-up that is actually useful and not to expensive. dont' worry about 300 bar vs. 200 bar. I would get a thermo valve and use a DIN firststage. 21% is fine.

dive the rig a few times with a buddy to get comfortable before going solo.

don't waste your money on a SpareAir, your life is at stake.

spencer

Hi hoovermd,

Surely you mean surface air consumption (SAC), not "max O2 consumption"?

My SAC is a maximum of 18 litre per minute, determined by my D9, transmitter and Suunto dive manager software. For ease of math, lets call it 20 lpm, which is actually pretty average.

From the SAC we can calulate a respiritory minute volume (RMV) which is my SAC when influenced by depth, work and stress. In an OOA situation at 30 metres (4 bar) my SAC could be expected to double due to stress and work.

Apply a mean pressure over the ascent from 30 metres of 2.5 bar and my RMV could be 100 lpm (SAC x 2 x 2.5).

My ascent time from 30 metres will ideally be no slower than 10 metres per minute, i.e. 3 minutes = 300 litres (100 lpm x 3), plus a 3 minute safety stop at 5 metres (SAC x 2 x 1.5 x 3) = 180 litres.

So I need a minimum of 480 litres of bail out gas to get me home (without deco) from 30 metres. My 3 litre 300 bar pony carries 900 litres fully charged. Hell, I can afford to loiter a while...

But today I found myself alone at 26 metres, on a single 12 x 300 of 21% back gas and my 3 litre pony, with a run time of 27 minutes and 3 minutes of mandatory deco on the clock. "It'll probably be all right" I thought as I kept triggering the shutter...

HTH, Tim

21% is fine.

36% is better. I'd rather be getting rid of nitrogen in an emergency, not adding to the load...

Hi hoovermd,

 

Surely you mean surface air consumption (SAC), not "max O2 consumption"?

Actually, the numbers I have are actual O2 consumption.

This number is used by Athletes.

SAC is another measure that is typically used by divers.

I stand corrected! Its the first time I have seen 'O2 consumption' applied in diving.

So long as one's bail out gas is not hypoxic nor (significantly) too rich for the operating depth, is O2 consumption relevant?

I stand corrected! Its the first time I have seen 'O2 consumption' applied in diving.

 

So long as one's bail out gas is not hypoxic nor (significantly) too rich for the operating depth, is O2 consumption relevant?

Not really.

Just an interesting number that I had on hand form a treadmill test..

I guess it means that at 40% my CuFt last longer

I have made an emergency ascent from 86 ft. with no air.

That is why I always like to carry some sort of backup.

As a minimum I carry a spare air. As mentioned above it is solely for emergencies. As such it is a lot better than nothing. I usually check it with my luggage. If I'm diving locally I use the H2O2 Odessy system which will screw into any size tank with a standard valve size on it. I use a 6 cf tank.

With these small size cylinders I know I will always have one with me. Much better than a larger cylinder which will tend to get left behind far too often.

All the arguments for larger cylinders are logical. The problem is will you always have it with you and ready to use? The spare air is simply a backup in a situation that you feel your abilities and training level would allow you to make a free ascent from in an emergency. As such it is much safer than trying that free ascent. Even if you have done it for real before.

36% is better. I'd rather be getting rid of nitrogen in an emergency, not adding to the load...

but hardly necessary, hence "21% is fine". OP is looking for a emergency bailout, not a stage bottle. I would hope OP is not diving to such depths for such times as to require a higher % to help a deco obligation...

I have a 40 I slung, but didn't like how cumbersome it is when carrying a DSLR. I got a 19 to strap to my tank, and it works fine, but I discovered I don't dive solo! (I was just getting ready to) so now I don't bring the ponies at all.

spencer

just get an AL19 with a simple reliable reg and a button spg - either slung(in the way for photog) or attached to your primary cylinder with the reg over your shoulder. That should get you to the surface from 100', but I would probably not go that deep solo with that configuration. Then you have a "real" set-up that is actually useful and not to expensive. dont' worry about 300 bar vs. 200 bar. I would get a thermo valve and use a DIN firststage. 21% is fine.

 

dive the rig a few times with a buddy to get comfortable before going solo.

 

don't waste your money on a SpareAir, your life is at stake.

 

spencer

This is exactly what I use. The slung 19 does not get in the way of the camera at all, so long as you clip the camera off to the opposite shoulder. Further, at 19 is still small enough that you can mount it directly on your primary cylinder if you like. I prefer to sling it however, as you can hand it off to a diver in need quite easily.

Dave

Not really.

Just an interesting number that I had on hand form a treadmill test..

I guess it means that at 40% my CuFt last longer

Well, guess it would on a RB system but not OC.

As for putting nitrox in a pony it can be a slippery slope - I dive with a number of guys who regularly deco out on their 'spare pony air' as it shorts their deco.

They tend to get annoyed when it is pointed out that carrying a cylinder of say 50% (and in one case 100% ) O2 so that they can shorten deco as well as having 'spare' gas is just fooling themselves when they regularly hit it on most dives