advice on pony bottles

[paul@]

Hi can anybody give me some advice on pony bottles. I have a spare regulator and thought it would be a good idea to have a pony for safety. I usually dive between 20 and 30 meters. would a 3 L tank be enough ? thanks

 

[M_Bipartitus]

I sugest you search for "rock bottom" for calculations on the amount of air needed to safely get to the surface from depth. A 3L is likely enough, but you should learn to calculate how much you will need.

 

[paddler3d]

I went with a pony, which I sling, which is 1/3 my back gas.

 

[azchipka]

When doing your calculations remember that the average diver in an emergency is said to use about 300% more air per breath then when they are calm. If your diving at 30 meters you may want to include time for a stop on your way to the surface in your calculation.

I used to carry a spare air unit with me on deep dives as a secondary option to my alternate air supply for my students. I stopped doing that the first time a student grabbed it at 85' and sucked every thing out of it in a single breath.

 

[Rhone Man]

That is the equivalent of about a 21 cubic foot pony (on the US system). Unless you are engaging in decompression diving, or have a huge air consumption rate, that ought to be able to get you safely to the surface (with time for a safety stop) in the event of catastrophic gas failure.

 

[kanonfodr]

21 cubes is just enough for a single diver with a stressed SAC rate of 1.0 to make a slow ascent, with a 50 foot deep stop, then 1 minute stops every ten feet to surface, from 100 feet. Theoretically, you should be fine.

Me? I sling an AL40, because I don't want to have to worry about my backup cylinder being enough.

Peace,
Greg

 

[burna]

Hi can anybody give me some advice on pony bottles. I have a spare regulator and thought it would be a good idea to have a pony for safety. I usually dive between 20 and 30 meters. would a 3 L tank be enough ? thanks

I have a 2.7 litre (20cuft) pony that I sling on deeper dives. I have calculated it has sufficient gas to ascend at normal rate with stops at 15 metres and 6 metres with some left over. I haven't tried it yet though.

The problem with it, is it costs the same as a 12 Litre tank to get filled!!! :cussing:

I am now going to [eventually] get an 11 litre Al which I can stage for deeper dives.

Because it will be so much bigger, I won't need to get it filled every time if I have used just a little (testing at depth to make sure it's working) or the reg free flows (which can empty a pony bottle in seconds) and also I can also use it as a second tank when I'm just doing shallow dives.

 

[jimlockNJ]

Many LDS rent Pony bottles. My suggestion would be to rent one that is 3 litre and use it (with plenty of Gas left in your primary) and see how it does. That is always the way you should test out key pieces of gear. Calculations are great, but doesn't replace using your gear and testing it out. Many people have confidence in Spare Air's until they actually try to use them at depth and realize how few breaths they actually give you.
When you try it out, breath heavy and make your ascent as slow as is reasonable. Make sure everything you do is on the conservative side when testing. If you dive for 30 years and only need your pony bottle once, it was worth every penny you could have possible paid for it!!

 

[Hatul]

Hi can anybody give me some advice on pony bottles. I have a spare regulator and thought it would be a good idea to have a pony for safety. I usually dive between 20 and 30 meters. would a 3 L tank be enough ? thanks

19 cu ft should do. I made the mistake of getting a 13 cu ft and now have to get the 19.

Adam

 

[a22shady]

Go with a Luxfer Alum40. Atleast thats what I have been told and a lot of the people I know dive with.