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| Originally Posted by chrisch Two options really. First twin 7L giving 14 litres of usable gas or twin 10s giving 20 litres of gas. The pony cannot be considered as usable gas so the 15+3 is 15 litres only.
Twin 7s are nice to dive with but all the hassle of twins for not much gas. Twin 10s are great but a bit too short for most people and can be hard to do valve shutdowns and hard to trim right. Most twin users prefer twin 12. (You can, if you look very hard, find long 10L tanks that make very good twinsets)
You will find much argument and disagreement in the twins vs. pony debate. A decent buddy should be your first redundant gas source and a pony is a work-around if your buddy is crap. Where a pony is useful is in shit vis where buddy separation is a real possibility. You need to be practised with the pony and it needs to have enough gas to get you topside with all the safety stops and plenty of reserve. A 3L pony is therefore not IMHO big enough if matched to a 15L single. You will however, find many that disagree...
The odd sizes of 15/3 also make a very unbalanced rig. You need two regs so you're nearly running twins anyway...
A 12L + 3L makes far more sense but to my mind is overkill for dives in the 12L single tank range. Again many folks will disagree.....
The real problem for me is that people just get into the habit of the pony and it becomes an "every dive" accessory with little thought as to why. these folk then bang on about "its not safe to dive without one" (which is total bollocks) and before you know it everyone thinks it is a necessity. Add this to the (incorrect) view that they don't need any training or skills and we have the sad situation where the misuse of a pony has killed people - ironic for a supposed "safety" device.
In the final analysis its really down to where you want to go with your diving. As you get more experienced you will start to look at redundant gas sources. The pony (its called a bailout really - pony is American) is a dead end. Its not suited to decompression diving due to size (some very experienced divers that hardly breathe disagree but they should shut up and remember not everyone is that good) so you will go to twins anyway.
IMO and in my experience starting down the twinset route earlier pays dividends. I wish we had moved to twin 7s as an intermediate position instead of going from single 12s to twins. I struggled a lot and TBH I'm still not totally comfortable yet.
Pony tanks can be a useful tool (ice diving for example) but like any tool you need to think why you need it and not simply take it with you every dive. The faded orange buddy jacket 15L + 3L auto-air and semi-dry diver is sadly still with us when things have moved on......
Chris |
If I'm going deeper than 15M, I'll normally take the 4L pony. And I love my 15L too, I usually leave the water with 100bar still in it, but that's cool. I don't do deco dives, so I reckon the 4L gives me plenty for anything upto 40M. It's sideslung, so the mouthpiece is basically right next to my occy anyway, I really don't see a great deal of need for any parrticular training in it's use; I'll usually have a quick toot of it on most dives, so I'm familiar with it's position in an emergency.
I'd far rather ascend in an OOA independently on my pony than hanging off someone elses hose. And the one & only time I ever went OOA when diving with an octopus, my so-called buddy, on a GBR day boat refused to let me take it, so I'll never put myself in a position where I'm relying on someone else for something that basic, ever again.
Also do the maths on air sharing. At 30M, your buddy goes OOA, grabs your occie, you had 90 bars left but now he's in a panic and sucking it down at 50L/min SAC. Your buoyancy is up the creek, you push off the bottom, finning and dumping air to try and maintain neutral buoyancy, you stop finning and BUMP you're on the bottom again, he's also dumped all his air in trying to prevent a fast ascent.
I know it shouldn't happen, but it does.