Max depth with pony

[LenC]

Personally, I would't go deeper than 60' with a 19. Under no conditions deeper than sport depths, but at 130 you are pushing the envelope. I have to concur with Captain12pk. I have never felt that I had too much gas on a dive. If you have the 40 and it isn't a problem for you, I wouldn't change.

 

[jeckyll]

Hey guys, I was wondering what are the deepest depths you could return to the surface in an OOA emergency with a 19 cu ft pony, and a 30 cu ft pony respectively. I currently use a 40 cu ft pony, and although I've never needed it, I am interested in sliming down to something a little smaller. I know I could return to the surface from the limit of recreational scuba with my 40, would it be possible with a 30 or 19? Thanks!

Maybe you shouldn't be diving all that deep until you can work these things out yourself.

Do some searching and figure out how to do 'rockbottom' calculations for you and your dive buddy.

 

[scawt]

I have seen stressed divers reach a sac of over 3cuft/min/ata so given the right conditions, you can triple some of the calculations above.

My opinion, stick with the 40 and learn how to use it and proper gas management.

Just my thoughts.

Scott

 

[dumpsterDiver]

I take a 13 down to 180 and a 6 cu-ft to 130 feet. Determining the minimum size pony is all about assumptions. Are you willing to ascend at 60 feet per minute for a good portion of the ascent? Are you assuming that you will immediately leave the bottom the instant you go on the pony? Are you going to assume that you need a safety stop during the emergency that required the use of the pony?

If you make very aggressive assumptions (SAC rate is relevant too) then you can get by with a small pony.

If you are going to assume that you are going to screw around on the bottom while breathing the pony, that you will ascend at 30 feet per minute, that you will do non-mandatory safety stops during a true emergency, that your buddy will simultaneously run completely out of air as well and need to buddy breath from your pony... and throw in a deep stop as well,,,, if you go that route then you need a BIG pony.

A few months ago I ran out of air at 120 feet (it got hard to breath) while over exerted and had to switch to my 6 cu-ft pony. I dropped a piece of gear right after I started the ascent and realized that with this very small pony, i could not afford to descend for even 30 seconds and grab it. Myu bad decisions (and small pony) cost me a piece of gear on that dive.

You need to balance convenience versus what degree of safety you want to "pay" for.

 

[redacted]

I have run my 13 cf pony from 85 ft in practice (I acknowledge a 13 may be pushing it with deeper dives by some divers). I did a slow ascent, 1 minute at 30, and 5 minutes at 10 - 20; and reboarded the boat with about 500 psi. I went with a 13 because it travels well. I'd rather have a 19 for destinations that do not include air travel but if you are not flying, then I see little reason not to carry a 30 or 40. I'm not sure why folks want to use an elevated (panicked) SAC for calculation when you switch to a pony. I carry a fully redundant pony so I won't be OOA if something happens to my primary source.

 

[DaleC]

I only calculate the volume needed for one diver using a pony as I don't plan for both divers to go OOA at the same time (two failures).

 

[Dr Wu]

To be blunt if you're asking this question you dont really understand enough to be using a pony (it hints you already use one without knowing its limitations).

This is correct.

The fact that you don't understand how to calculate the solution to your question proves a pony is nothing but a liability for you.

You should cease diving with it until you understand how it works.

And once you fully understand how it works you will probably no longer want it anyway.

 

[Nemrod]

I use a 19 to 130 feet (if anything actually), beyond that I would as soon be on doubles, just depends, in some cases I would already be on doubles, in other cases I might not even make the dive, in general, a 19 is more than adequate for ascents from sport diving depths. It was not stated if this was solo or buddy. If you are going to include your buddy on the pony, better go with a 40.

If your buddy has a similar rig, then, how many tanks and regulators are you going to take on a dive before redundancy for redundancy for backup gets to be ridiculous.

N

 

[DevonDiver]

Hey guys, I was wondering what are the deepest depths you could return to the surface in an OOA emergency with a 19 cu ft pony, and a 30 cu ft pony respectively. I currently use a 40 cu ft pony, and although I've never needed it, I am interested in sliming down to something a little smaller. I know I could return to the surface from the limit of recreational scuba with my 40, would it be possible with a 30 or 19? Thanks!

Your SAC/RMV is going to greatly influence this. It will vary depending on the person and the situation. In an emergency, your breathing rate can become highly elevated - so this should be accounted for also (pony is an emergency device).

You can calculate your SAC/RMV using the tool on my resources page:
Scuba Resources

There is also a 'rock bottom' calculator linked there, which will help you calculate your gas requirements and turn points. This can also be used to determine your ponys various capabilities (gas duration at different depths, with and without a buddy also using it).

Hope that helps...

 

[VooDooGasMan]

DaleC has a point, lets answer the op question, a pony can go a 1000' or more, yet your reg might only be rated for 500' or so, does not matter on cf size.

Hope this helps.



Happy Diving