Optimal Pony Bottle Size for Failure at 100ft?

[VikingDives]

However, divers diving doubles or sidemount have generally put some time into thinking about their configuration and training with it, formally or informally.

It takes the same amount of thinking to decide to add a pony bottle as it does to purchase doubles or a sidemount rig. How much practice, formal or informal, do you think the average rec diver needs to learn to do the most complicated pony bottle gas switch? In my experience, most people look pretty smooth after about 5 switches with a slung pony that has the valve closed and the second stage stowed.

Let's say they practice this on their own, and get reasonably competent at doing it. Then they never do a switch again... Are they any worse than a doubles diver who taught themselves to do a valve drill 5 years ago and hasn't practiced since?

 

[rjack321]

I have been utilizing a 30cu ft. pony bottle that I "stole" from a friend a while back, but am evaluating the purchase of a new pony.

A bit of background: I frequently dive deep-ish wrecks where most of our time is spent between 75 and 100 feet. While I do not venture out on my own, I do often dive in teams or am separated from a buddy at a distance that would be too far for him to acknowledge my situation or provide me with emergency air. I do not perform wreck penetration alone, under any circumstances.

So, the question that I'm asking is what size pony would be optimal to address a failure that occurs at 100ft.? - which I think is a reasonable depth to work with for this exercise given my type of diving.

3) This is a solo thread. If the OOA diver had their own pony, would they have been safer?

Where did you get the impression this is a solo thread? It's in the advanced subforum (not solo) and the OP explained the dives they want the pony for right in post #1.

It takes the same amount of thinking to decide to add a pony bottle as it does to purchase doubles or a sidemount rig. How much practice, formal or informal, do you think the average rec diver needs to learn to do the most complicated pony bottle gas switch? In my experience, most people look pretty smooth after about 5 switches with a slung pony that has the valve closed and the second stage stowed.

Let's say they practice this on their own, and get reasonably competent at doing it. Then they never do a switch again... Are they any worse than a doubles diver who taught themselves to do a valve drill 5 years ago and hasn't practiced since?

"Practice on their own" has got to be the worst idea ever. I'm sure we have all seen divers who are an absolute mess underwater and have no clue they are a mess. Because they have never had any critical constructive feedback - or someone tried once, they got all defensive and nobody bothered to talk to them again.

 

[VikingDives]

Where did you get the impression this is a solo thread? It's in the advanced subforum (not solo) and the OP explained the dives they want the pony for right in post #1.



"Practice on their own" has got to be the worst idea ever. I'm sure we have all seen divers who are an absolute mess underwater and have no clue they are a mess. Because they have never had any critical constructive feedback - or someone tried once, they got all defensive and nobody bothered to talk to them again.

I agree, but the point I was trying to make was you can be just as incompetent with doubles...

 

[KenE]

I believe we have gone OT again. The question is size of pony, not pony vs other options.

 

[FishWatcher747]

I'm seeing a lot of (paraphrased) "pony bottles are no big deal, no downsides, just grab one and go diving" which implies essentially zero training in their use. And I'm not aware of a pony bottle speciality card, even from PADI... However, divers diving doubles or sidemount have generally put some time into thinking about their configuration and training with it, formally or informally.

You have good arguments. But they almost universally apply to backmounted pony bottles. A slung Pony is not Rocket Surgery. One can't mix up the regulators.

 

[OMyMyOHellYes]

I mean, it seems that way. But the problem is when they do as they trained and try to switch to the pony regulator, but it's nowhere to be found. Likewise, the other regulator that they should have been breathing is going to be ... where? This is not a long hose setup so it won't be clipped off somewhere predictable or hanging on a necklace, the reason they're not breathing it is that they messed something up earlier and it might as well be dangling somewhere behind them. Panic in 3, 2, 1, ...

As poor as I think my OW training was, they did teach us how to find and re-insert a loosely flopping second-stage reg underwater. Engrained even with limited schooling in the skill.

I just don't see it even remotely being an issue with minimum training and more than a few dozen actively firing neurons.

 

[ofg-1]

Optimal Pony Bottle Size for Failure at 100ft?​

Any size pony can fail at 100'. The larger ones just make more bubbles when they do.

 

[SlugLife]

To help keep this thread on-topic, I've branched the whole "are pony bottles dangerous" discussion into another thread....

Info - Are Pony Bottles Dangerous?

Branching off another thread, which went mildly off-topic: Are pony bottles dangerous? What are the hazards of pony bottles? What safety advice would you give to someone using a pony bottle? What other advice (sizing, selection, configuration, etc) would you give for pony bottle use? This is...

scubaboard.com

 

[mr_v]

@chrisjur, your math is correct and 40cf is a very good size pony bottle for the dive plan. However, it is possible to restate some nuances and clarify your assumptions.

When you have a failure - any failure - you may fix it fast and won't have to spend 3 minutes at depth. However, at that time you will suck a lot of air. Your heart rate will increase substantially, so in a single minute you may consume as much as as you would in 3 minutes. Therefore, your math is correct. Assume that 1 minute of failure will last you 3-5 real minutes. And this is conservative. If you don't dive trimix, there may be some narc'ing going on at that depth.

You're also missing one assumption - in the case outlined in the original post, you presume a direct vertical ascend. What if you dive a wreck and need to get back to the upline? What if you need to shoot a bag? Therefore, I'd add a 100ft swim to your assumptions just in case... You should be able to use a 40cf bottle even w those calculations. Anything smaller is just silly.

 

[MidOH]

40 swims best anyways.