Pony rigs

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Re: Pony rigs

Postby binklebonk » Tue Aug 27, 2013 7:53 pm

divepirate wrote:OOG diver inside a wreck gets 7ft reg hose from diver outside wreck.

Neither have any redundant air source, diver inside consuming Air at higher rate.
Both divers become in OOG situation.


I hope it ended well, but really, LOL...
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Re: Pony rigs

Postby AndrewRawlingson » Tue Aug 27, 2013 8:53 pm

binklebonk wrote:Fair enough Andrew, but your calcs assume that you are the one needing the gas. Not everyone will have their shit together in a tense situation and be breathing at a moderate rate.

I have heard (possibly apocryphal) that many OOG situations arise from divers other than those you enter the water with. For a newbie in a freak out, a SAC rate of 75 isn't unreasonable to consider for calcs. IMHO.


We are talking about single cylinder + pony versus single cylinder. This is not about pony versus twinset.

Even with the SAC of 75 L/min, a 3 L pony should get you to the surface from a 30 metre no deco dive.

For all but the shallowest dives, I'm diving solo and carrying gas for a buddy just doesn't come in to it.
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Re: Pony rigs

Postby binklebonk » Tue Aug 27, 2013 11:05 pm

AndrewRawlingson wrote:Even with the SAC of 75 L/min, a 3 L pony should get you to the surface from a 30 metre no deco dive.
Why define the OOG situation so optimistically? I (and most others I know) plan BO and deco gas for worst case scenarios, i.e things going wrong at the last minute of the bottom time or greatest return distance to travel. With that in mind, for NDL diving I assume that an OOG will arise with a combination of factors, worst case: too long and too deep (not an uncommon reason for folk to run out of gas), so potential for a real deco ceiling or at least ongassing worthy of a good safety stop. 600L of gas with a freaked diver at (worst case) 40m with a possible ceiling is not enough.

Options are good things to have underwater. If you are going to the hassle and expense of a pony get one that's useful.
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Re: Pony rigs

Postby AndrewRawlingson » Tue Aug 27, 2013 11:58 pm

binklebonk wrote:
AndrewRawlingson wrote:Even with the SAC of 75 L/min, a 3 L pony should get you to the surface from a 30 metre no deco dive.
Why define the OOG situation so optimistically? I (and most others I know) plan BO and deco gas for worst case scenarios, i.e things going wrong at the last minute of the bottom time or greatest return distance to travel. With that in mind, for NDL diving I assume that an OOG will arise with a combination of factors, worst case: too long and too deep (not an uncommon reason for folk to run out of gas), so potential for a real deco ceiling or at least ongassing worthy of a good safety stop. 600L of gas with a freaked diver at (worst case) 40m with a possible ceiling is not enough.

Options are good things to have underwater. If you are going to the hassle and expense of a pony get one that's useful.


There is no end to this discussion. How much gas is enough gas? If you're pushing the idea of a twinset, then I can't disagree, as long as you can use it of course. What I don't understand is the resistance to adequate, albeit limited redundancy. Would you rather be a 30 metres with no gas or a 3 L pony? I know what I would choose.

Regarding an unplanned 40 metre dive with a decompression commitment, a 3 L pony is not adequate redundancy in my opinion. But if you're getting yourself in to this kind of mess, I don't think a twinset strapped to you back will save you either.
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Re: Pony rigs

Postby binklebonk » Wed Aug 28, 2013 7:32 am

AndrewRawlingson wrote:
binklebonk wrote:
AndrewRawlingson wrote:Even with the SAC of 75 L/min, a 3 L pony should get you to the surface from a 30 metre no deco dive.
Why define the OOG situation so optimistically? I (and most others I know) plan BO and deco gas for worst case scenarios, i.e things going wrong at the last minute of the bottom time or greatest return distance to travel. With that in mind, for NDL diving I assume that an OOG will arise with a combination of factors, worst case: too long and too deep (not an uncommon reason for folk to run out of gas), so potential for a real deco ceiling or at least ongassing worthy of a good safety stop. 600L of gas with a freaked diver at (worst case) 40m with a possible ceiling is not enough.

Options are good things to have underwater. If you are going to the hassle and expense of a pony get one that's useful.


There is no end to this discussion. How much gas is enough gas? If you're pushing the idea of a twinset, then I can't disagree, as long as you can use it of course. What I don't understand is the resistance to adequate, albeit limited redundancy. Would you rather be a 30 metres with no gas or a 3 L pony? I know what I would choose.

Regarding an unplanned 40 metre dive with a decompression commitment, a 3 L pony is not adequate redundancy in my opinion. But if you're getting yourself in to this kind of mess, I don't think a twinset strapped to you back will save you either.

You seem hellbent on redefining the discussion. No twinset has been mentioned by me. We are talking about ponies and a single.

You ask if I'd rather be at 30m OOG with no pony or a 3L? Well I reject the dichotomy. The question is invalid as it precludes the many other scenarios that can be encountered.

People getting themselves into messes is what carrying redundant gasses is for, why be panglossian about it?
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Pony rigs

Postby AndrewRawlingson » Wed Aug 28, 2013 8:06 am

Good morning! So if not a twinset, you are advocating a bigger pony or better buddy skills? Personally, I regard redundant gas as a way of dealing with equipment failure, not as a ticket to do what ever the hell you like underwater. I don't know how you plan for the latter.
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Re: Pony rigs

Postby binklebonk » Wed Aug 28, 2013 11:01 pm

AndrewRawlingson wrote:Good morning! So if not a twinset, you are advocating a bigger pony or better buddy skills? Personally, I regard redundant gas as a way of dealing with equipment failure, not as a ticket to do what ever the hell you like underwater. I don't know how you plan for the latter.



I am advocating a minimum size based on an assessment of might go wrong (worst case not best case). If you are just doing 10m OW dives then yes 3L is satisfactory.

I really don't think you understand (or haven't bothered reading what I wrote) for you to be implying I think redundant gas is "a ticket to do what ever the hell you like underwater".
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Re: Pony rigs

Postby AndrewRawlingson » Thu Aug 29, 2013 12:09 am

binklebonk wrote:
AndrewRawlingson wrote:Good morning! So if not a twinset, you are advocating a bigger pony or better buddy skills? Personally, I regard redundant gas as a way of dealing with equipment failure, not as a ticket to do what ever the hell you like underwater. I don't know how you plan for the latter.



I am advocating a minimum size based on an assessment of might go wrong (worst case not best case). If you are just doing 10m OW dives then yes 3L is satisfactory.

I really don't think you understand (or haven't bothered reading what I wrote) for you to be implying I think redundant gas is "a ticket to do what ever the hell you like underwater".


Good evening! I am also advocating a minimum size, so we agree on that. In my first post on this thread, I said that I dive with a 6 L side slung cylinder, so I think we have a similar approach.

If I haven't misinterpreted, where we disagree is on the minimum size of bailout for a non-deco recreational to a planned depth of 30 metres. You quote a SAC of 75 L/min. Working through the gas consumption calculations, a 3 L pony will get you to the surface if you start your ascent straight away and ascend in a timely manner. There is no margin for error and there is no doubt that more gas is a good thing, but it will suffice. We should probably leave it there. As I said, it's an endless debate and since we all get to dive how we like, it's just a point of discussion really.
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Re: Pony rigs

Postby Ulsterkiwi » Thu Aug 29, 2013 6:54 pm

divepirate wrote:An example of this is something that crossed my desk the other day.

OOG diver inside a wreck gets 7ft reg hose from diver outside wreck.

Neither have any redundant air source, diver inside consuming Air at higher rate.
Both divers become in OOG situation.

You can't plan for the stupidity of others.


I think this is a really good point.

I was very recently on a motorcycle course. The point of the course was to get riders to think through what kind of situations would threaten their physical safety/life and how would they respond and then try out some of the skills necessary to do this. We were left with a toolbox of items to think about and to practice so that if we found ourselves in a situation like that our responses would be practiced and therefore more likely to succeed and leave us alive and in one piece.
Lots of discussion was had about "what if..." which included what other bikers do. The main instructors asked what kind of people ride motorcycles? His suggested response to his own question was cool, sexy, intelligent people because only they survive and the rest are taken care of by natural selection.
Its a bit harsh but it is valid.

We are discussing good practice here, we all probably elect to dive with those who follow good practice, can we really do much for those hell bent on testing the theory of natural selection?.............
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Re: Pony rigs

Postby Ali Perkins » Sat Aug 31, 2013 1:53 am

AndrewRawlingson wrote:If I haven't misinterpreted, where we disagree is on the minimum size of bailout for a non-deco recreational to a planned depth of 30 metres. You quote a SAC of 75 L/min. Working through the gas consumption calculations, a 3 L pony will get you to the surface if you start your ascent straight away and ascend in a timely manner. There is no margin for error and there is no doubt that more gas is a good thing, but it will suffice.


It seems to me that even though a 3L pony might get you (or + someone else) to the surface, if there's the possibility that it could be that tight or touch and go to make it, it's going to be a pretty traumatic experience. While you may not be able to plan for the stupidity of others, you can try. Carrying a 3L pony is certainly not planning for it, carrying something in the 6L range is going to give you some breathing space, and maybe you'll still want to dive again after said disaster has unfolded.
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Re: Pony rigs

Postby Ulsterkiwi » Mon Sep 02, 2013 10:30 pm

ok, seems like I missed some of this conversation when making my last post.
Funnily enough I started this thread to ask how to carry a pony, not to ask how big my pony should be. Anyway, I would never shy away from a robust discussion.

It does seem to me however that all the what ifs in the world remain just that. What if for example I planned for what I thought was worst case and as a result I took a fully charged 6l pony, what if on this particular dive it all went to custard and I needed 6.2l of air charged to 200BAR to get comfortably to the surface, my planning has fallen short by a bit and its less comfortable than I would have wanted.
I think I made it pretty clear what kind of diving I do. A lot of people would argue I don't "need" any redundancy at all. To my mind, with the provision I have made I have improved my chances of recovering a crappy situation by quite a margin. For sure I could have gotten a bigger pony, by the same token I could have taken my wife's two 12l steelies, bought a manifold and bands, bought a BP/W and then my planning would have met with full approval of all. Thing is, my planning wasn't about that, it was about making provision for the diving I do. If I planned for the diving I might do I would probably not pay the bills for a while and eating might be a problem :-)
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Re: Pony rigs

Postby binklebonk » Mon Sep 02, 2013 11:03 pm

The difference I see is that if you have a moderate sized pony (6L) then you have prepared for the contingencies that can be reasonably expected to be encountered. Why would anyone take this to be a catch all for everything?

This thread isn't just about your diving, it's not about giving you approval as that would be an arrogant thing to do. Many folk who do different diving read these threads and I think it is important to prevent endorsing the minimum of "what you can get away with". For your diving it's clearly enough.
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Re: Pony rigs

Postby Ulsterkiwi » Tue Sep 03, 2013 10:49 am

binklebonk wrote:The difference I see is that if you have a moderate sized pony (6L) then you have prepared for the contingencies that can be reasonably expected to be encountered. Why would anyone take this to be a catch all for everything?

This thread isn't just about your diving, it's not about giving you approval as that would be an arrogant thing to do. Many folk who do different diving read these threads and I think it is important to prevent endorsing the minimum of "what you can get away with". For your diving it's clearly enough.


That is pretty much what I was trying to say, the thread was actually about how to carry a pony and it has grown to something else. Fair enough. Your point about others reading is very valid and a healthy discussion is useful to all.

I also agree with your query as to why a 6l pony should be treated as a catch all for everything but to my mind what you have written has that idea underlying......

Options are good things to have underwater. If you are going to the hassle and expense of a pony get one that's useful.


ergo anything other than a 6l is not useful......

For a balanced discussion I would argue that the rig I have is useful within limitations as any rig will have limitations. I have seen the 3l v 6l discussion on other forums and inevitably people start quoting SACs, capacities and otherwise displaying their mathematical prowess to show how only a 6l is useful. Absolutely, it is twice as useful as my 3l but not nearly as useful as a 9l and so the merry go round continues.....

Andrew made a point about preferring some redundancy over none, I tend to agree. I also agree, for my kind of diving what I have done is enough. Is that the same as "minimum of what you can get away with" perhaps it is! It all becomes semantics then.

I made reference to the GUE system, from what friends who dive this system and what I have read about it tells me, part of the philosophy is a GUE diver only takes what is necessary for that dive. Surely that is a "minimum of what you can get away with"? Maybe I am mistaken.

I think your point of being aware of all who may read the discussion is very valid. What I would suggest should be the focus of this discussion then (now that we have left sling or cambelt far behind) is whether or not we are truly taking into account the various factors involved in the diving we are doing?
For clarity sakes here is an example of what I mean...
Lets say I regularly dive on Thoms reef for crayfish. Due to the nature of crayfish diving and the currents there it is not uncommon to get separated from my buddy. Even if we assume best practice and following separation I do NOT continue the dive until the end of the planned time (and lets face it that is a common practice with many divers on this site) there is always a risk of an OOA or equipment failure scenario developing. Even if I limit my depth to 30m thats still a long way up in one of those situations. I have a 3l pony with a good quality well maintained regulator on it. Am I going to regret not spending another $100 for a 6l? Well, I don't actually know what I will think at that point precisely but I am pretty sure that amongst it all I will be thinking "thank f*** I have this pony"

I tend to think the next most important step is not to consider pony size but that I start to have that discussion with my buddy and wider diving circle and encourage them to think about what they will do if they get separated from me and they get into difficulties. I am already having those conversations after someone on the boat said "Oh I am going with Paul, he has a pony...."
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Re: Pony rigs

Postby Ali Perkins » Tue Sep 03, 2013 11:42 am

Ulsterkiwi wrote:I made reference to the GUE system, from what friends who dive this system and what I have read about it tells me, part of the philosophy is a GUE diver only takes what is necessary for that dive. Surely that is a "minimum of what you can get away with"? Maybe I am mistaken.


I think you are mistaken. I don't think that's a good summary of the GUE philosophy. I also don't think you'd ever see a GUE diver with a 3L pony bottle.
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Re: Pony rigs

Postby Ulsterkiwi » Tue Sep 03, 2013 1:13 pm

Fair enough.
Please do not think I was trying encapsulate the GUE philosophy with that one comment, I do understand GUE is much more far reaching than that. Having said that I was referring to a phrase I have heard mentioned on more than one occassion by GUE divers and it seemed pertinent to this discussion. I think your assertion about GUE divers carrying a 3l pony is absolutely spot on and that is definitely not what I was suggesting.

I think the GUE system has (unfairly in many cases) been accused in the past of lauding itself as the ultimate if not the only system worth considering. I think that is part of the problem when discussing something like redundancy. There is a perception at least of a "my way or the highway" approach from the tech/GUE world. (please don't jump down my throat, I have described this as a perception not a fact!) This can be a huge turn off for decent discussion and sadly I have seen it happen amongst my diving friends with both sides equally to blame.
As I said above, I would love to see divers of all styles and systems really thinking about and discussing the dives they are planning and what scenarios they should be planning for within that. There is if anything a tendency to think that "someone" will take care of things we should take responsibility for ourselves like an OOA or equipment failure situation.
Not that I am making this about me but one thing which has pleased me about setting myself up with a pony rig has been the questions and thinking it appears to have provoked. The appearance of the rig has been variously interpreted as my wanting to dive for longer or deeper, wanting to dive on my own all the time, liking the idea of twins but going for a cheap option, not trusting my gear, having had a near death experience or otherwise wanting to push the envelope. The simple fact that I wanted to add redundancy and therefore be better prepared has often been the last thing to occur to some I have spoken to. The fact we are having those discussion is a good thing though....isn't it?
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