Is a 6cf pony bottle good enough as a back up?

[elan]

Didn't know snorkeling HAD a minimum pony bottle specified for the activity.... Is that in one of then new dive manuals?

Yes it is used for cooling down the drinks as it was explained above, while snorkeling....

 

[GrumpyOldGuy]

No. Why are you even asking this?
6cf is kinda like "snair air" - it sets you up to thinking it will help you, but in the end it's useless.

19cf is minimum from 100ft
13cf is minimum for 50 ft
6cf is minimum for snorkeling

For Hoovers, this is a good rule.

For an experienced diver who knows what his gas requirements are and takes the time to practice, its a stupid generalization.

 

[AbyssalPlains]

Adiabatic cooling.

Edit: to be more precise the air cools as it leaves your cylinder due to the decrease in pressure. This cool air can suck the heat out of a drink thereby cooling it. It is the same principle that freezes regulators into an open position when diving in very cold water.

OK, I get the theory, but I'm trying to picture the actual setup in my mind. You open the gas cylinder and let the escaping gas flow around a glass of martini? Or how would you do it?

 

[StuartT]

If your going to sling a pony for emergency gas 19 cu would be the smallest I would use. I use a 40 and most of my dive buddies use 30 or 40's. Once you are in the water you don't really notice the extra bottle anyway. Just my 2 cents.

 

[Kenr]

No. Why are you even asking this?
6cf is kinda like "snair air" - it sets you up to thinking it will help you, but in the end it's useless.

19cf is minimum from 100ft
13cf is minimum for 50 ft
6cf is minimum for snorkeling

Hardly useless. I use a 2.7cf for dives up to 30 meters so 6cf sounds great to me. I have been diving mostly in Asia and almost never see anyone carrying any reduntant gas. If you are dragging around 19 to 40cf tanks then more power to you and you will cetainly be safer than I. But for the most part on my trips i don't see divers having any backup air. My setup weighs just 2 lbs, packs easy for travel and fills off my tank so its easy for me to setup and most importantly it get used. If I were going deeper, caves, etc., someplace a reduntant supply is needed i would certainly carry a decent size pony.

 

[jaycanwk]

The best backup for a 120 would be an H valve, no? Why carry around another tank with that big of a primary? For no-decompression diving, I can't think of a scenario in which one could empty a 120 tank without going well into deco. If we are talking deco diving, then why bother with a single tank in the first place? I'd go doubles in that case.

An H valve is not redundant air. One scenario I can think of off hand would be a blown O-ring, which would empty your tank with that H valve on it.

Jason

 

[jd950]

No. Why are you even asking this?
6cf is kinda like "snair air" - it sets you up to thinking it will help you, but in the end it's useless.

19cf is minimum from 100ft
13cf is minimum for 50 ft
6cf is minimum for snorkeling

I am sorry to be the one to say this, but if a 6cf tank would be useless to you in safely ascending from 50', then your skill set is one that should prohibit you from providing advice on this topic.

As if that were not bad enough, if you believe a 6cf pony is required when snorkeling, perhaps you should stay away from the water unless closely supervised and perhaps wearing those inflatable arm float things.

On the other hand, if you were being facetious, and have nothing useful to say, why even participate?

In response to the OP, the earlier posts concerning depth issues, goals and safety seem to be dead on. I would add that if air travel is a factor in your diving, you may need to consider some compromises in size. A 6, 13 or 19 is fairly easy to pack or carry. Larger tanks begin to cause problems.

If diving solo I typically limit myself to a max of about 40-50' because if need be, I could CESA from there, but even a 6 would allow me to ascend normally from such depths and that would be safer. Even if for some reason it only got me through a safety stop, or perhaps only got me to 15' and I had to forgo a stop, my risk of injury would be reduced finishing my ascent from there without any breathing gas, as opposed to a CESA from 40-50'.

Get the largest tank that you are willing to routinely use. A 40 back on the boat or in your garage is less useful than a 13 or even a 6 that is with you on the dive dive.

 

[Dr Wu]

Is a 6cf pony bottle good enough as a back up?

Yes. It is just fine as a backup.

If so whats a good one to buy ?

Yellow ones are nice.