A DIR spin on an old question

[b1gcountry]

I think the DIR answer is to either:
1. Find a better, more reliable set of buddies to dive with, and possibly
2. Move up to a larger capacity steel tank if you need more gas in order to maintain a safe reserve or
3. Start looking into the added redundancy and extra capacity of a set of doubles.

The Non DIR answer would probably be that since you are only using the pony as an emergency reserve, you will likely not be emptying/refilling it between most dives, so air will be simpler since it is an acceptable bailout at any depth you are likely to be using a pony at anyway...

Tom

 

[Tortuga68]

Sorry, but I disagree with this statement. Nitrox is not only to extend bottom time, which using the "best mix" is intended for; the highest F02 at a set PP02

Um, using nitrox doesn't extend bottom time, it extends NDL. And by definition, best mix is best mix, period

I'd switch to it if my back-gas became inaccessible due to equipment failure

So worry about ending the dive safely, not your SI

I was hoping to get some input from divers who think with an approach I consider sensible and safe, that's why I asked it in this forum (it's not about the DIR answer, but rather the opinion of DIR divers), instead I've essentially been advised to take the question elsewhere.

Bull****, you got a heap of good advice from people that are more interested in your well-being that what forum you posted in

 

[b1gcountry]

I just read the thread through. Just curious, DTaine, you do live in Florida, don't you? You are probably ideally situated to find DIR minded divers to dive with, so what's up? I sincerely believe that my wife and I are the only GUE trained divers in St Louis, but I still manage to find decent people to dive with. If you're in Miami, you just aren't trying (no offense). Look up a couple people. Call up Dean Marshall, and ask about an upcoming Fundies class. Heck, just ask him for a list of people to dive with that have recently taken Fundies, or whatever. When I first started getting interested in DIR stuff, I was asking the wrong questions. It sounds like you are too. Dive with someone who knows their SH&T It will help a lot.

Tom

 

[jeckyll]

DTaine: You'll probably find a number of people who started with a pony only to progress towards doubles. Probably a few in the DIR forum dove this way earlier, before getting DIR training / finding like minded divers.

The question really is better in a non-DIR forum though, because as mentioned the DIR answer isn't going to be in line with what you seem to be looking for.

I've got a 40cf bottle sitting next to my doubles that hasn't seen the water more than 5 times. I switched to doubles shortly after the 'slung pony' and took DIR fundamentals not too long after that. I'm not doing deco dives yet (if ever), so for now it's just collecting dust.

If I need more gas I'm in doubles.

I don't get a chance to dive with as many DIR minded divers as I'd like, but one of my main dive 'buddies' has adapted some of his gas planing & profiles to suit my type of diving and that's been very helpful.

At the end of the day, I don't want to be in the water with people I wouldn't trust to be around when the brown smelly stuff hit the fan.

Hopefully you'll get a chance to dive with some folks that can help in you answer some of those questions by their actions in the water and in person on land, instead of having to try and pick this stuff up from the internet.

Best of luck!

Bjorn

 

[AndyNZ]

Just to clarify to make this easier: 1) I'm not trying to accelerate deco on the safety stop 2) it is just for reserve on dives with questionable/insta buddies 3) I haven't dived with the tank yet as I haven't set it up to sling yet & 4) I'll be getting my Nitrox cert soon, I'm diving air now

To be honest, I think the best forum for your question is (typing in a very quiet voice) the solo divers forum, not the DIR one.

I'd happily give you more of an answer there, or PM me for more details - I teach a recreational course using slung pony bottles for redundancy for the very same reasons you have stated. Useful, IMHO, but not "DIR".

The course does cover the issue of diving with different mixes in back gas and the pony - neither richer or leaner mixes in the pony are ideal, for a number of reasons, assuming that your aim is redundancy. Anyway, a non-DIR answer to a non-DIR question in a DIR forum....!

 

[coldsmoke]

I think that's a very fair question. I like a lot of DIR principles, like the necklaced backup, but I'm not diving DIR because I'm not part of a regular team, and I'm not doing the kind of diving that requires DIR.

For example, necklaced backups are starting to show up in non-DIR training. That's a specific area where DIR design principles can improve safety for all divers. I think OP is looking for the same kind of guidance on backup gas (or a backup buddy?) in instances where he specifically isn't diving in a team scenario with highly qualified buddies.

A necklaced backup is not exclusive to DIR. It is also HOG, Naui Tech, DSTAT, IANTD, etc, etc. It's a common misconception that DIR is about the gear or gear configuration. While DIR does specify the types (not brands) of gear and the configuration of that gear, the basic platform is built from the Hogarthian system. Those who invented (created, promoted, whatever) DIR did not invent the backplate and wing, the long hose, nor the necklaced backup. They did establish protocols for team diving.

This is why the OP is having such a hard time getting his question answered. The fundamental level of DIR is the "team". All other considerations - gear type, gear configuration, and protocols are built around that team. To ask a question that essentially asks what kind of gear should I use if I don't have a good team, just can't be answered in a DIR context.

I feel your pain. My closest DIR buddies are 6 hours away. I only get to dive with them a handful of times a year, but I still log around 70+ dives a year. I don't refuse to dive locally, I just don't do DIR dives locally. Most of my dives are not DIR dives. I wish they were, but I am a victim of where I live. I do consider the risks however, and plan my dives more conservativly. I am trying to build a local DIR team, but the going is sloooowww.

I would take TSandM's and Tom's advice and try to find local DIR divers and try to build a local team. Diving with my DIR buddies that live 6 hours away is the most fun diving I do. It's not because the conditions, viz, or scenery is any better that where I live. It's because no diving I have done yet compares to the comfort and ease of diving with other DIR divers.

Good luck with your quest.

Hunter

 

[Anti-Hero]

Um, using nitrox doesn't extend bottom time, it extends NDL. And by definition, best mix is best mix, period

Yes, it extends your NDL, which can extend your bottom time given the gas supply. I'm not going to argue semantics.

So, Mr. best mix, riddle me this: What would the best mix be for a 30 foot dive? And since this is the DIR forum don't say air. (To avoid any more semantics, air being defined as 21% O2, and 79% N2)

Hint: It's well beyond the 40% allowed by recreational nitrox certification.

 

[Blackwood]

And by definition, best mix is best mix, period

But has nothing to do with DIR whatsoever.

 

[DaleC]

Dtaine, here is a link to a thread I started to discuss switching gasses (from EAN 32 to air) at 100'. A lot of good discussion about gas mixing resulted from it.
http://www.scubaboard.com/forums/advanced-scuba-discussions/253407-switching-gas-mixes-100-a.html
While I am not a DIR diver myself I actually respect the DIR philosophy and understand why it can't be piece mealed out. The system only works if you accept it as a whole. Having said that, Hunters comments are intriguing as I spend time here to gain a "DIR" perspective on gear configuration and use (which I think Dtaine is doing as well). Am I correct in assuming it is more accurately described as a "Hogarthian" perspective?

 

[TSandM]

If you take the gear configuration out of the context of the team philosophy and the DIR diving protocols, you just have a gear configuration, and maybe it's Hogarthian . . . although I've heard Bill Main doesn't like some of the DIR prescriptions, himself. Maybe all you have is a gear setup, where some of the equipment and configuration decisions have been made on the basis of other assumptions that you aren't aware of and aren't using -- which makes those gear decisions invalid for YOU.

A beautiful example is single tanks and no ponies for recreational dives. It works in the context of team diving, solid situational awareness and communication, and practiced emergency skills. It DOESN'T work well for random instabuddy diving . . . which is why such diving settings are not DIR dives, no matter what the gear, or the training, of the diver contemplating such a dive.

My first exposure to this came when my original OW instructor just about had a coronary over the idea of sharing gas and shutting down the valve when a single tank diver had an uncontrollable freeflow. In HIS world, you would never shut down the gas carried by any diver, because of the risk that that diver would, at some point, end up separated and adrift by himself, and require that gas to survive. In my world, that just doesn't happen, and if it does, I CAN turn my own valve on. Different assumptions; different solutions.