Spare air or pony

[rongoodman]

That's a thought. Gas managment would be a little more complicated, as opposed to just keeping the pony in reserve in case of a problem. I haven't been able to spend in time in the water yet in my doubles, although they're set up and ready to go. I'm hoping to get some pool time after the first of the year.

 

[EvaL]

Central Fla,
You're probably aware by now most on this board are against SpareAir and most haven't used or own one. I come from a slightly different perspective, I used to own a SpareAir (for 2 years, carried it on >50 dives) but recently switched to a pony for some of the reasons pointed out here. Mainly: I believe 57 breaths refers to surface breaths. If I recall correctly, at, say, 80ft, it has less than 8 breaths. I tested my SpareAir at 80ft - it breathed wet and way worse than my regs. If you're going deeper than 60ft, I strongly recommend a pony tank instead. For a safe ascent from 99ft or less, a 13 cu ft pony tank is barely sufficient (19 cu ft is better); for 132ft or less, a 19 cu ft pony tank is barely sufficient (30 cu ft is ideal).
Dive safely.

 

[Web Monkey]

String it will help me if you tell me why spare air is useless.

How long will a pony 6cf last??

Thanks

I'm not String, but try this:

A semi-stressed diver can easily have a SAC rate of 1.0 CFM. At 66', that's 3 CFM. If you spend a minute at depth trying to figure out what your problem is, you now have 3 Cu Ft left.

However, due to a pesky gas law and the design of the regulator, you can't get all of the remaining 1500 PSI out of the tank, which will leave you with somewhere around 2 Cu Ft of air, which is probably just enough to get you to the surface if you fin like crazy.

If you use a small pony, like a 19, you can spend time figuring out what went wrong, then do a nice, slow, normal ascent, including a safety stop, and arrive on the surface with plenty of air left.

Terry

 

[Cheekymonkey]

Thats interesting what your saying about the lung volume dude, I'm gonna have to go look that up, while I am a beleiver that spare airs are not acceptably large enough a volume, I would be curious to find out hte specifics .

 

[String]

Try http://en.wikipedia.org/wiki/Lung_volumes

Then find someone thats so calm when OOA they breathe at a totally normal rate

FWIW the number of breaths and the time arent really related. The time is using a fairly average SAC (again for normal breathing) so its a far more reliable figure than breaths.

 

[Wildcard]

Or you could just practice your CESA.....

 

[TNdiver6387]

I know nothing about spair air or pony bottles, but i want to mention something about lung volume and breathing, which i do know a little about. That 6 L mentioned (according to that wikipedia article, although that is just an average and all the numbers vary person to person) is total volume, not functional volume. No one EVER uses their total lung volume while breathing, its not physically possible. The actual maximum ammount of air we can breathe in and out is whats known as functional volume or vital capacity. According to that chart that number for the average person is 4.8 L. There is a certain amount of the air that it is imposible to exhale. Also, according to that chart the average breath is .5 L. I personally think that is a little low, but 1.5 doesnt seem at all unreasonable for a normal calm breathing.

 

[friscuba]

Just saw this on their website that made me laugh



1.6 litres per breath?! Not even an infant has that low a lung volume.

Average person breathing normally uses 3.5 to 4. A full lung is about 6.

The nitrox version is really really making me laugh. Yeah 20 seconds of a nitrox mix will make a REAL difference to the no doubt rapid ascent you just had because you were stupid enough to get OOA with no backup.

Hey String, let me oppologize to you in advance if this has been brought up already (I haven't read the entire thread yet), but there is lung capacity, and a thing called lung tidal exchange or something thing like that. NOBODY breaths their entire lung capacity in a normal, or probably abnormal, breathing pattern. While a person may have a 6 liter or greater capacity, in general they may use only a fraction of that full capacity in the normal act of breathing... hence the 1.6 liter exchange the source was using.

I can get 48-52 , many deeper than normal, breaths out of my spare air on the surface, but I can fill my old XL US Divers Cousteau (haven't tried it with what I'm diving now) in 4-5 breaths if I want.


Now on to my thoughts on Spare Air in general... It all depends on what kind of diving you do. For technical or overhead diving, it's probably not appropriate, but for average Joe recreational diver who has no restricted access to the surface, a Spare Air should be just fine. Now if you are completely trapped in fishing line or net, maybe the pony might come in handy, giving you extra time to work an escape out, but it's still no guarantee.

 

[Cheekymonkey]

Why is so much of not functional, lung fluids?

 

[Wildcard]

The word is tidal volume. The volume of inspired air with each breath.