carrying pony bottle and oct reg as spare air...

[moneysavr]

I agree and indeed like this response - informative and impartial. I like the idea of securing the pony directly on the back, I will need to investigate if I can get 2 tanks on my BCD.

Another question which is for anyone actually - your thoughts on the 3cu.ft "Spare Air"?

Spare air is a PS IMO its fine if you do a dive in a local swimming pool at 10FSW

The Back mount pony Naysayers allowed their opinion,My pony is live and leak tested on every dive,I use a small SPG but have a longer one for solo diving that I right hip D ring clip,
On every dive you should check all your gas,and a pal should give you a look over on a set depth prior to going into the dive for any leaks -Heck I am jumped all the time with my dry bleed Sherwood's for cold water!
This weekend a small leak was found on my wing and the dive was fine as I had back up lift capability's.

You can buy several styles of clamps and pony straps to put your pony on your tank some quick release as the one I have to pass off to a troubled diver if needed and it will work with most systems,my trim is not affected pony or no pony at all.
Brad

 

[Web Monkey]

Another question which is for anyone actually - your thoughts on the 3cu.ft "Spare Air"?

I can't take credit for either of these.

Someone here once said that the Spare-Air is the perfect piece of equipment if you want to run out of air twice.

Someone else said it's just right if you want enough time to think to yourself "Oh ****! I'm out of air!"

If you want to know what size tank you need for a pony, there's an Excel spreadhseet here that will run the calculations for you, if you give it your SAC and depth and tank size.

Unfortunately I don't have a link to it, but it works out that for an average SAC, a 19 Cu Ft is good for an ascent (including stop) from around 80', and a 30 or 40 Cu Ft is good for at least 130'.

Note that your mileage may vary, so you need to run the calculations for your own numbers.

Terry

 

[birdwrasse]

my test on my new 13 cu. ft. pony tank

starting with 3000 PSI / (avg of 161 PSI/minute)

one atmosphere -- 0 ft; 18.6 minutes
two atmospheres -- 33 ft; 9.3 minutes
three atmospheres -- 66 ft; 6.2 minutes
four atmospheres -- 99 ft; 4.6 minutes

...and if i remember right, as we ascend, the air will last longer.... so, these times are max bottom times... i think the psi is higher here than in a 80 cu ft tank (which i'm averaging in the 50's) because there is less volume... is that correct?

i'll try the pony tank at 33 ft when i get my new 1st stage and put in on my computer to recalculate the figures to see if they are the same...


feedback, please...



--carlos

 

[Sasquatch]

Watching Thread

 

[TheRedHead]

i'll try the pony tank at 33 ft when i get my new 1st stage and put in on my computer to recalculate the figures to see if they are the same...

If you know your surface air consumption (SAC) rate expressed in cu feet per minute, then you can calculate how much you would consume at any depth. But with such a small pony bottle, if you ever need to use it, you need to make an immediate ascent.

 

[birdwrasse]

that's what i did... i want to do it underwater after i've been swimming around to simulate my breathing pattern after being under a little bit.

i'm trying to figure out, with the size tank that i have, if it's realistic to think there is a good amount of air to surface at a conservative pace, stop at 15 ft for 3 minutes, then surface... i'm not one for panicing and at times when situations have occured, i stayed calm, fixed them, and continued with my dive.

 

[TheRedHead]

if it's realistic to think there is a good amount of air to surface at a conservative pace, stop at 15 ft for 3 minutes, then surface... i'm not one for panicing and at times when situations have occured, i stayed calm, fixed them, and continued with my dive.

I would think so unless you are hoovering air. Even if you run OOA at 15 feet, you should be able to surface slowly on one long exhale. You don't have time to look for an anchor line at depth. That's what a bigger tank would allow you to do.

 

[birdwrasse]

i think so, too... i don't push myself and know my limitations, so the pony bottle adds some sense of security... let's hope i never have to use it in an emergency! (that is, an emergency never happens, but i would use it if one did happen... )

 

[Packhorse]

Here is a XL spreadsheet i made up.
Its in metric but im sure you can work it out
19cf= 3litre
28LPM = 1CFM SAC
you can change any fields in green to suit.

edit: failed for some reason I will try again later

 

[Diver Dennis]

I personally don't like a pony tank on the back. If you want to know why, read this thread:

http://www.scubaboard.com/showthread.php?t=74063&highlight=Dandy+Don+Pony+OOA

This is a scuababoard classic and my apologies to Dandy Don.

Do you mean because it was leaking? The pony should never have been used in that situation, he should have ascended. I can hear small leaks coming from my first stage and to completely empty his pony, it must have been quite a large leak.