9 replies to this topic

[peterbj7]

I await Trace's input, but I'm sure others have valid views. I was reading GI's paper on gear configuration, and noticed his statement about the backup regulator (we are told NOT to call it anything else) that "..... must be a non air balanced, low performance reg".

I understand low performance, to a point. You don't want any risk of its free flowing, though when you do use it you don't want it to be too much of a hardship. But why "non air balanced"?

I've always had good results with a couple of Jetstreams, with the one I'm not using switched to -ive. But that seems to place me way beyond the bounds of DIR.

[Diverbrian]

Strange when I read an article by JJ in my IANTD Tech Diver's Encyclopedia that HE mentions that the back-up reg should be as good as the primary (after all, you will be breathing from it if your buddy runs out of gas).

I dive two Aqualung Legend LX's. They are definitely high performance, overbalanced, diaphram regs. And most of the techies up here dive similar regulator set-ups. Sorry but I don't like sucking my breathing gas through a straw at 100 ft. or deeper, LOL.

[TraceMalin]

I await Trace's input, but I'm sure others have valid views. I was reading GI's paper on gear configuration, and noticed his statement about the backup regulator (we are told NOT to call it anything else) that "..... must be a non air balanced, low performance reg".

I understand low performance, to a point. You don't want any risk of its free flowing, though when you do use it you don't want it to be too much of a hardship. But why "non air balanced"?

Obviously, the unbalanced regulator will have decreased performance which will help to prevent lost gas due to freeflow as you point out. As with any DIR component, one has to imagine how it will be affected by the speed of the scooter through the water and high flow currents in caves. While George has stated that back up regulators should be "non air balanced" he has also been known to say that a diver can use any "air balanced" regulator that can be detuned without eating its seat and the venturi assist switched to "off."

The simplicity of a "non air balanced" regulator has some benefit. As always, the more moving parts something has the more can go wrong. That's why upstream design is frowned upon because of the need for a pressure relief valve in the first stage -- just another failure point.

Additionally, you don't want side baffles, shower head style regulators which would more easily allow water in while scootering. And, you need to be able to open and clear it of debris underwater.

Trace

[Latitude Adjustment]

Scooters?!!! Talk about failure points!

[TraceMalin]

Scooters?!!! Talk about failure points!

Well, 18,000+ feet is a long swim into a cave as is another 18,000+ feet back out. I think scooters have their benefits for the WKPP which outweigh their failure points. Besides, they used a fleet of them carefully managing the burn times.

Trace

[ScubaDadMiami]

Once something is written, it stays forever. Things change. Equipment changes. People change. Be careful about reading old news and then assuming it is still current information.

So long as you can set up and use a regulator that does not free flow in current while scootering, you have done half of the job. So long as that regulator is also capable of handling high demand, life support situations, you have done the other half.

The thought used to be that the less performing regulator did the job adequately on balance. It still would and there are many who still go this route. However, some of the best peformers can be adjusted to avoid free flow problems but can be dialed and switched to perform as well as the primary in a second. All the bases are covered. That is an even better way to go.

I dive two Aqualung LX Supremes tuned equally. I set the backup (short hose on the neck strap) on surface and detune with the dial before the dive. Once in the water, I can dial and switch so that it performs identically as my primary. No problems even in heavy current while being towed. Works for me.

[peterbj7]

Once something is written, it stays forever.  Things change.  Equipment changes.  People change.  Be careful about reading old news and then assuming it is still current information.

Yes, but GI's paper is still being promulgated so one must assume that the DIR people intend it still to be taken as advice (or should that be "mantra"?). I certainly don't agree with it any more than you seem to, and I wouldn't have agreed with it had I read it hot off the press whenever it was written. The problem is he did not express his views as opinions, but as undisputed fact that should be observed by divers. THAT aspect is what I find untenable about DIR.

This sentence is new. I am in favour of standards being introduced and followed where it is important that uniform kit layouts are used, which generally refers to group operations in high stress/high task loading/poor visibility situations (and maybe others besides). The fact is that these standards are usually introduced at the start of a mission anyway (and of course must be), whether or not "DIR" is being used. And these are varied over time according to equipment, circumstances, personal experiences, etc. etc. DIR appears not to permit this natural evolution, and this is why I consider it not just irrelevant but actively undesirable.

Edited by peterbj7, 10 December 2004 - 12:43 PM.

[ScubaDadMiami]

Once something is written, it stays forever.  Things change.  Equipment changes.  People change.  Be careful about reading old news and then assuming it is still current information.

Yes, but GI's paper is still being promulgated so one must assume that the DIR people intend it still to be taken as advice (or should that be "mantra"?). I certainly don't agree with it any more than you seem to, and I wouldn't have agreed with it had I read it hot off the press whenever it was written. The problem is he did not express his views as opinions, but as undisputed fact that should be observed by divers. THAT aspect is what I find untenable about DIR.

No question about it, it often does come out that way or at least seems to. In fact, I have my own issues about the zero variance cadre mentality.

[jextract]

You guys might appreciate this:
http://www.singlediv...wtopic=1229&hl=

[wreck_maniac]

That's funny Jex...where'd you ... wait , I posted that

Anything George says is gospel...don't you guys know this by now? (was that prejudice)