Tdi not dir

[Web Monkey]

The DIR answer, as I understand it, is that a second SPG introduces additional failure points with no gain since once you close your isolator you've thumbed the dive and you're going to get out of the water with the gas your and your buddy are carrying, which will be adequate.

That sounds reasonable too, although I'm actually willing to make the trade-off of an extra potential failure for a little extra comfort (knowing how much gas is left) during an emergency.

I wouldn't ditch an instructor for either opinion.

Terry

 

[Rainer]

What good does knowing really do in this case? You've planned the dive to be able to get back in case of a manifold (i.e. non-reg) failure, and if you've isolated for just such a case, you're already going home. You either have the gas or not. I guess it might give you forewarning about when you'd go OOG, but your team is already there. Seems silly to me, but not the end of the world by a long shot.

 

[danvolker]

Or maybe he just goes places where RB is more practical. If that is the only reason you think people dive RB you have truly been brainwashed.

Certainly not brainwashed..if you check the Techdiver list archives on aquanaut.com , you will see I am one of the "original voices" for DIR.
What I would object to is an instructor not wearing the same rig as the student, on an intro to tech diving course. There are too many buddy drills that would not work well with a rebreather....and I have used rebreathers...but with all the nonsense you have to go through to maintain a high safety level with rebreathers, I have to have a "mission specific" reason to use one.

Please tell me you are not defending the instructor using the rebreather on an intro tech course?

 

[nereas]

The DIR answer, as I understand it, is that a second SPG introduces additional failure points with no gain since once you close your isolator you've thumbed the dive and you're going to get out of the water with the gas your and your buddy are carrying, which will be adequate.

The fallacy in their answer however is that there IS a gain having two of them, because with two, you can validate either SPG's performance with the other, and this is a gain. Another gain is that it will tell you whether your isolator is actually open, on the outside chance you failed to open it before entering the water, two gains. People are human and humans make mistakes.

Even so, it is not a big deal either way. I would not now hook up 2 SPGs unless the group involved in the dive wanted everyone to do so. Protocols are protocols, and group dynamics is always a major consideration. The GUE-DIR group has their own specific protocols, and there is no use pretending any of them is written in stone by the finger of god. Rules of the group are simply rules.

 

[Rainer]

The fallacy in their answer however is that there IS a gain having two of them, because with two, you can validate either SPG's performance with the other, and this is a gain. Another gain is that it will tell you whether your isolator is actually open, on the outside chance you failed to open it before entering the water, two gains. People are human and humans make mistakes.

Even so, it is not a big deal either way. I would not now hook up 2 SPGs unless the group involved in the dive wanted everyone to do so. Protocols are protocols, and group dynamics is always a major consideration. The GUE-DIR group has their own specific protocols, and there is no use pretending any of them is written in stone by the finger of god. Rules of the group are simply rules.

Why not just validate the SPG against what you think it should be at? With practice, you'll always be within a few hundred PSI if the gauge is working correctly. Shoot if you're tracking average depth and time, you can work out what the SPG should be at (given a known SCR). It's only hard if you don't practice.

And your isolator example makes no sense. If time has gone by and the numbers aren't moving on the SPG, well, then you didn't open your isolator or the SPG is busted; pretty easy to then diagnose which it is. This is also why we do mod valve drills before jumping into the water and on descent...

 

[Bismark]

The fallacy in their answer however is that there IS a gain having two of them, because with two, you can validate either SPG's performance with the other, and this is a gain. Another gain is that it will tell you whether your isolator is actually open, on the outside chance you failed to open it before entering the water, two gains. People are human and humans make mistakes.

Even so, it is not a big deal either way. I would not now hook up 2 SPGs unless the group involved in the dive wanted everyone to do so. Protocols are protocols, and group dynamics is always a major consideration. The GUE-DIR group has their own specific protocols, and there is no use pretending any of them is written in stone by the finger of god. Rules of the group are simply rules.

I am curious, if you have two and they disagree, which one do you believe? Two people who agree do not necessarily have the right answer.

 

[krumpet]

Thanks for the replys I was being a whinger, Ill just do the course & next time Ill do it through someone else, but anyway I don't like this guy just like alot of you on yourself tekies, you can have your **** together without loving yourself & thinking your great if some tek head wanted to act like my dad on the street I'd smash his head in. Rebreather or twin tekie I don't care one day I'll be as experienced or more than them. And to all the nobs on this site that want to reply like a smartass nerd . Nereas your a tosser mate.

 

[krumpet]

If I could delete this thread I would but just forget it Im leaving this site now forever & going diving, see you round nereas

 

[Bismark]

There's much to be said for diving DIR, but there's also much to be said for diving independents and there are many other flavors of perfectly acceptable approaches. Much of the noise that advocates of one system or another make is sheer nonsense. If your with an instructor who knows independents, if you want to learn the GUE approach, take a GUE course later. Every approach has advantages and drawbacks and a thinking diver will learn to tell one from the other. The only reason that I can see for rigid adherence to one system or another has more to do with a team agreement to do so that with the ultimate superiority of one system over another,

Bingo! Way to much noise on the internet and not enough thinking. DIR is not an agency. TDI or GUE are agencies. I know of some non-GUE Tech instructors who teach their course in a fashion that is very similar to a Tech I GUE course. (Yes, I am speaking from experience). GUE does not have a patent on DIR teaching. It sounds like you have already made up your mind about diving DIR, but without any experience with Tech diving, how did you make this decision? One of the main points of DIR is to develop a "thinking diver". How are you doing this is you are making a decision before becoming familiar with the alternatives? I have chosen the DIR path, but I did so after much experimentation and question asking. It works for me and I think it is a very methodical, well thought out system. That does not mean I am not open to other ideas. Moreover, I encourage pretty much anyone to make up their own mind but only after experimenting, learning, asking questions and making an informed decision. Remember, in solving problems underwater, you will need to be a thinking diver, regardless of which agency you choose. Do not settle for "just because" answers. If you instructor has an opinion, he should be able to defend his decisions. So should you. Sadly, as Thalassamania stated above, there is too much noise and not enough common sense in the dir-non dir debate. Spend the time learning from your instructor and if you decide you don't want to dive the way he does after the class, then you are free to make that decision and you will do so from an informed position. Learn first, then make your decision.

 

[nereas]

I am curious, if you have two and they disagree, which one do you believe? Two people who agree do not necessarily have the right answer.

Use your common sense! Since you cannot fix the problem underwater, you will need to resolve it later, and go with the most conservative reading in the meantime.

Did that seem like rocket science?