Rec Diving a Pony

[James79]

Sorry, can't resist... for days every time I see the title of this thread this is all I can think of;

 

[doctormike]

I think it is, because the simultaneous failure for single tank and pony could be in two regulators, as opposed to the manifold failure, which is a (sort of) tank valve. Tank valve failures are much less common than regulator failures. So, two of those could certainly be a higher probability than a single valve failure. Most manifolds have 3 consecutive static o-rings guarding the uncontrolled loss of air through the cross bar, (meaning all three would have to fail on a given dive) and a valve seat guarding uncontrolled loss in one of the cylinders in the isolator, and valve stem seals guarding loss in the other cylinder. I'm not sure that there has ever been a confirmed case of isolator failure actually resulting in total gas loss from both cylinders in manifolded doubles.

However, two consecutive regulator failures is also extremely unlikely, unless there were environmental reasons for the failure, like a freeze up. So you're very likely safe with either.

I think that post that you are responding to was a misunderstanding, as explained upthread. There was no concern raised about simultaneous failure of a single tank (back gas) and a pony rig, which would be incredibly rare. The point was about how a manifold lets you access all of your gas if you have a single failure of one regulator (either first stage, second stage or LP hose). Complete redundancy (pony bottle) eliminates the issue of manifold failure, but the tradeoff is that you can lose access to some portion of your gas completely.

Here is one more thing that I think is important when we are discussing accidents and gear failures. It is very difficult to get accurate information about fatalities, given the limits of these databases and the legal issue involved, but at least they do exist. There is absolutely no standard for reporting or archiving information about equipment failures that don't result in a death. So saying that there is no data or statistics or confirmed report of failure X just means that in our online conversations and/or personal experience, we have never encountered such a situation. That may mean that failure X isn't extremely common, but it doesn't mean that it doesn't happen (as you can see from the last few posts in this thread).

 

[Colliam7]

However, two consecutive regulator failures is also extremely unlikely . . . . . . So you're very likely safe with either.

I think this is a very reasonable summary. I dive BM manifolded doubles, and I dive BM singles, with a pony. And, the only difference for me is the amount of bottom gas I am carrying (the pony does not count toward that). Either configuration affords a redundant gas supply as far as I am concerned. And, I consider - in the absence of any actual data - the likelihood of a simultaneous 'double' regulator failure with a BM single and a pony, to be equivalent to that of an isolator manifold failure on my doubles - i.e. VERY (very, very, very) low.

For RECREATIONAL diving, particularly boat diving, I slightly prefer a BM single with a pony, because some boats just don't accommodate manifolded doubles very well in their cylinder slots. If I know a particular boat does, however, then I may go with my doubles, simply to obviate the need to change cylinders between dives. But, overall, 6 of one . . . .

 

[halocline]

My approach, not saying this is the answer for everyone, but it is for me, is to simply avoid situations in recreational diving where I do not have immediate access to either the surface or a dive buddy. If I am diving in a situation that requires redundant air, I use doubles. This includes all overheads; I used doubles for my cavern class and all subsequent cavern dives prior to my cave classes.

One of the basic tenants of open water, recreational diving as defined by the major agencies is to always have immediate access to the surface. The surface is the ultimate alternate air source. I believe that pushing the limits of recreational diving, and relying on a pony to do so, is something that many divers who lack technical dive training do. I believe that in SOME CASES (not making any accusations here) this is a false sense of security, because diving in a more aggressive manner, whether it's excessive depth, lack of buddy support, risk of entanglement, unpredictable currents, navigation complexity, whatever, is by it's nature riskier. Simply carrying a small bailout bottle only addresses the issue of immediate loss of air, which is hardly the only issue.

I'm sure there are lots of divers with technical training who have the skills and experience to problem solve underwater and situational awareness/risk assessment to safely augment deeper or otherwise more challenging recreational dives with a small bailout bottle. That is their choice. I use mine for filling tires and soaking regulators, both fairly risk-free activities!

 

[Catito]

I use a pony. 2 first stages n 2 second stages for me.

The fundamental flaw in scuba diving is the octopus. Putting your alternate air source on someone else is a defective solution for an OOA situation.

Last sentence...why?

 

[Marie13]

You guys absolute insistence on doubles rather than a pony for deeper recreational diving makes me laugh. Once again, one size does NOT fit all!

I’ve got an online friend elsewhere on the Great Lakes who wants to get into deeper wrecks (beyond 100ft). She’s is an excellent diver, judging from the photos/videos I’ve seen, but there’s no way she’s going doubles. She’s about my age (early 50s), but with worse knee issues than I have. There’s no way she can handle even my dwarf doubles (HP80s) up the boat ladder. She can handle a HP100 and a slung AL40 just fine. She’s been diving that for a bit and it works just fine. She has absolutely NO interest in going tech, so even attempting SM ain’t gonna happen.

 

[CWK]

Last sentence...why?

You should be able to access safety equipment 100% of the time.

 

[doctormike]

You guys absolute insistence on doubles rather than a pony for deeper recreational diving makes me laugh. Once again, one size does NOT fit all!

I’ve got an online friend elsewhere on the Great Lakes who wants to get into deeper wrecks (beyond 100ft). She’s is an excellent diver, judging from the photos/videos I’ve seen, but there’s no way she’s going doubles. She’s about my age (early 50s), but with worse knee issues than I have. There’s no way she can handle even my dwarf doubles (HP80s) up the boat ladder. She can handle a HP100 and a slung AL40 just fine. She’s been diving that for a bit and it works just fine. She has absolutely NO interest in going tech, so even attempting SM ain’t gonna happen.

Can you point to a post where someone "absolutely insisted on doubles"...?

If I remember correctly, this topic was started when someone brought up the topic of double 50, similar in weight to her HP100... It is one alternative to a pony for the diver who wants some degree of redundancy and access to all of their gas in case of a failure, and it was discussed as such. An option.

 

[jeffsky29]

I'd rather have a single 100 and a 30 Pony, rather than double 50's. Even if I dove double 50's, I would sling my 30, which becomes an issue when hunting. I always dive within the limits of my single 100, BUT if I ever get stupid (i.e. see something I always wanted to see, shoot or photo, and loose track of my air), I at least I know I have the xtra 30 to get me to the surface with a safety stop. Please no comments on how you are not supposed to get stupid when diving. I am not perfect and neither is anyone else on SB. I am diving since 1983 and have never, ever been OOA, but like Insurance that I have never used, if the **** does hit the fan, I am ready!

 

[jeffsky29]

I think this pony is dead!