30 to 40. anything over that. Get suited up for doubles. SLing the redundant air supply. avoid the word PONEY as it is a bad word and miss understood...
Correct pony bottle size?
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scubacoots3
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As most have already go with a 30 or 40
I'd go for a 3l (i think thats 30cu ft or a bit more).
With my SACs and so on it'll do me for no stop diving to about 33m (110ft) with time for ascent, 3 minute stop and some left over.
Deeper than that its time for a twinset;
However for 30-100ft or so when you just want some redundancy a twinset is often overkill. Big, bulky, PITA on small boats and so on, a simply pony is fine.
For planned deco dives etc obviously a twinset is the only sane option though.
You should be working out for yourself it it provides enough redundancy. Work out YOUR SAC, double it to factor in panic. Then work out how long its going to take to ascent at a safe rate and safety stop from given depths utilising that figure.
THAT will tell you what size tank you need for that type of diving. Its something you NEED to know for yourself anyway. This is something ALL people with ponys need to do, they need to know the maximum depth it'll get them safely to the surface from and when it wont. Otherwise the extra safety is nullified by a false sense of security and pushing the limits to the extent that the bottle doesnt have enough gas.
Everyones SAC is different, everyones stressed SAC is different so its something every single person needs to work out for themselves and be aware of.
With my SACs and so on it'll do me for no stop diving to about 33m (110ft) with time for ascent, 3 minute stop and some left over.
Deeper than that its time for a twinset;
However for 30-100ft or so when you just want some redundancy a twinset is often overkill. Big, bulky, PITA on small boats and so on, a simply pony is fine.
For planned deco dives etc obviously a twinset is the only sane option though.
You should be working out for yourself it it provides enough redundancy. Work out YOUR SAC, double it to factor in panic. Then work out how long its going to take to ascent at a safe rate and safety stop from given depths utilising that figure.
THAT will tell you what size tank you need for that type of diving. Its something you NEED to know for yourself anyway. This is something ALL people with ponys need to do, they need to know the maximum depth it'll get them safely to the surface from and when it wont. Otherwise the extra safety is nullified by a false sense of security and pushing the limits to the extent that the bottle doesnt have enough gas.
Everyones SAC is different, everyones stressed SAC is different so its something every single person needs to work out for themselves and be aware of.
Unfortunately that human brain has a slight software bug - it cant be relied on to to the correct thing 100% of the time in 100% of situations therefore its not sensible to rely on.
I concur. 19cf minimum, 30 is a good bet safer.
But I sling a 40 anyway, since it can double duty for tech diving.
If your buddy isn't sufficient, or if you choose to dive solo, I'd suggest manifolded doubles. Double 80's will work nicely for your range, and they provide excellent redundancy.
I wouldn't sling less than a 40.
When you look at a redundant backup, you need to calculate how much gas it will take for you to:
1. Recognize a problem and move to your bail out;
2. Sort yourself out and identify the source of the problem;
3. Determine whether the problem can be solved so that you can return to your back gas;
4. If not, return to your upline;
5. Ascend at a safe rate, making all required or recommended stops.
You should plan all of this using an elevated SAC rate. In addition, I'd suggest a safety factor of 1.5X. In other words, you plan on having 1.5X the amount of gas that it will take you to get to the surface. This covers contingencies, including taking too long to get to the upline or, for a really bad dive day, when your buddy goes OOG after you lose your back gas and have already gone to bail out.
When you look at the numbers, you'll probably see that a 40 is minimal for the deeper end of your range.
That's why I use doubles, with AL40's or AL80's for deco as required. If I don't need deco gas, then I'm happy with the doubles.
With regard to mounting, I would only consider slinging it like a stage. Tank mounting means that you can't see your bailout, which can lead to problems. It also means that you can't hand it off to a buddy if they need it.
I wouldn't sling less than a 40.
When you look at a redundant backup, you need to calculate how much gas it will take for you to:
1. Recognize a problem and move to your bail out;
2. Sort yourself out and identify the source of the problem;
3. Determine whether the problem can be solved so that you can return to your back gas;
4. If not, return to your upline;
5. Ascend at a safe rate, making all required or recommended stops.
You should plan all of this using an elevated SAC rate. In addition, I'd suggest a safety factor of 1.5X. In other words, you plan on having 1.5X the amount of gas that it will take you to get to the surface. This covers contingencies, including taking too long to get to the upline or, for a really bad dive day, when your buddy goes OOG after you lose your back gas and have already gone to bail out.
When you look at the numbers, you'll probably see that a 40 is minimal for the deeper end of your range.
That's why I use doubles, with AL40's or AL80's for deco as required. If I don't need deco gas, then I'm happy with the doubles.
With regard to mounting, I would only consider slinging it like a stage. Tank mounting means that you can't see your bailout, which can lead to problems. It also means that you can't hand it off to a buddy if they need it.
A lot depends on your primary air supply, not just your depth. If you were diving double 130s, you would want something bigger than if you were diving for example a single 80.
From the two choices that you were looking at, the 13 and the 19, I voted the 19 for several reasons. The 13 is too small except for open water unobstructed non-deco dives. The 19 is the same diameter as the 13 so it is hardly any bulkier if attached to your rig. The 19 has a larger increase of air capacity than it's increase in weight.
If you want more air, I prefer the Luxfer 30 over the Catalina 30 because the Luxfer is smaller in diameter and lighter.
With all that said, I personally mostly dive with either a low pressure S14 or a Luxfer S40 mounted to a set of double S40s. The S14 would be mounted between the tanks and the S40 would be mounted to the side of the tanks to make triples. If the S19 was available when I bought the S14, I would have bought it instead.
Back in the "old days", I used an E size O2 tank for backup air. It was about the same size as an S19.
I like to have my backup air on a QR so I can seperate it to give to my buddy if I have to.
Ron
From the two choices that you were looking at, the 13 and the 19, I voted the 19 for several reasons. The 13 is too small except for open water unobstructed non-deco dives. The 19 is the same diameter as the 13 so it is hardly any bulkier if attached to your rig. The 19 has a larger increase of air capacity than it's increase in weight.
If you want more air, I prefer the Luxfer 30 over the Catalina 30 because the Luxfer is smaller in diameter and lighter.
With all that said, I personally mostly dive with either a low pressure S14 or a Luxfer S40 mounted to a set of double S40s. The S14 would be mounted between the tanks and the S40 would be mounted to the side of the tanks to make triples. If the S19 was available when I bought the S14, I would have bought it instead.
Back in the "old days", I used an E size O2 tank for backup air. It was about the same size as an S19.
I like to have my backup air on a QR so I can seperate it to give to my buddy if I have to.
Ron
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