Recommendation for recreational pony bottle size

[redacted]

Use proper gas management and proper buddy skills and you will never need a pony.

Know your sac rate, plan your dive, and then dive your plan.

OR use proper gas management and a properly sized pony and you will never be dependent on a buddy for gas.

 

[DevonDiver]

The first step is to understand gas management - this both ensures you'll never run out of gas (except for regulator failure) and enables you to accurately calculate a reserve/redundant gas supply to fit your requirements (depth/duration/consumption rate).

Scuba Gas Management

 

[herbdb]

It's not about gas management, its about redundancy. The gas is not there to extend the dive. Using a pony bottle does not mean the divers are casual about gas management. To me it shows a degree on conservatism and caution. The ability to self rescue is big in my local dive community. That does't make us bad buddies.

Many of our ocean dives in the mid Atlantic region are near recreational limits. Some operators will not allow you on one of their "deep" trips without a pony.

For the OP, in my opinion a 30 cuft bottle will do at all recreational depths, a 19 is marginal. Once in the water you won't notice the difference.

 

[DevonDiver]

It's not about gas management, ....in my opinion a 30 cuft bottle will do at all recreational depths, a 19 is marginal.

In "your opinion" how does gas management not feature in deciding the appropriateness of the redundant air source?

i.e. what are you basing "your opinion" on... if not gas management? (i.e. calculated demand for a given dive - and selection of a redundant gas source appropriate in relation to that calculated demand)

 

[herbdb]

Don't get all testy on me. My post was in response to DiveMaster_Tom who thinks ponys are unnecessary if you are properly trained.

Your post is right on about selecting the correct tank for the dive and plan. I have a number of tanks, but I generally use a 30 cu ft pony, because in the water it is hardly noticable and it is suitable for any recreational depth. I guess I should make that "suitable for me".

--------
Edit -Wish I was in the PI. We have had about 14 inches of snow today.

 

[JohnN]

Not withstanding JohnN's calculations, do you really want to blow off a safety stop...???

Sorry I wasn't more explicit. Assuming the same 1.0 SAC (although things should calm down by the time you get that close to the surface), 3 minutes @ 15' is another 4.5 cf. For that 19 cf pony, you still have some gas to look at that last seahorse, or you could still make it back with 500 PSI remaining

 

[rhwestfall]

Bent is fixable, drowned usually isn't...... I'd prefer to have the gas and time for the plan, but as it is "encouraged", given the aforementioned choices, its not happening. That being said, I've opted for a 30cf (soon to be replaced w/ a 40cf should AN/DP/TriMix showm me its utility) for the diving I seem to do most, and likely allowing for that option to add additional safety.....

 

[DevonDiver]

I know this doesn't answer your question, but don't get a pony. Use proper gas management and proper buddy skills and you will never need a pony.

Know your sac rate, plan your dive, and then dive your plan.

Yeah, you kinda forgot about equipment (especially regulator) failures. Or buddy separations (or weak buddy competence). Plan your dive for those contingencies, and you're back to consideration of a redundant air source.

Don't get all testy on me. My post was in response to DiveMaster_Tom

Suitable apology offered for 'testyness'

Edit -Wish I was in the PI. We have had about 14 inches of snow today.

Sat on my balcony with a pot of coffee and laptop this afternoon wearing nothing but shorts and flip-flops. No excuse for being testy

 

[flots am]

I'm looking to purchase a back up spare breathing pony bottle system for recreational diving here in So. Cal. People have recommended the Spare Air others says go to a 6cf rig and yet others say go for a 13cf. I'm not a tech diver and the deepest I have ever gone is 100, but I usually stay between 40 to max 80 feet max. Any suggestions??? Thanks, Vlad

You can calculate it yourself (there are spreadsheets around to help with this), but the base # is your stressed SAC. 1CFM might be OK, but if the brown stuff hits the fan and you're in current, you could easily hit 1.5 or two.

A 19 would probably handle most situations above 100', however there is nothing to spare and it might not actually be enough. A 30 is much better and should handle anything you're likely to encounter on a recreational dive. The tradeoff is that a 19 is easier to manage, so it's really a tradeoff between convenience and safety.

A spare air is only useful if you have ditched your helicopter in 10' of water and need to get out.

 

[doctormike]

I know this doesn't answer your question, but don't get a pony. Use proper gas management and proper buddy skills and you will never need a pony.

Buddy separation happens, even with good divers and proper buddy skills, especially in low visibility.

The decision to use a redundant gas source has nothing to do with gas management. If you have one gas source and you lose it, you need a backup, no matter how big it is. First stage failure or a blown LP hose can happen.