Why Recreational Triox ??

[MikeFerrara]

Mike Ferrara has a point here - there is a lot of argument about semantics rather than the use of helium. The 30/30 mix does seem a bit odd to me, but then I have not done the GUE course so I will not put up a case against it. However the use of some helium in the mix from 130 to 150fsw makes a lot of sense. From 150fsw onwards helium is essential IMO.
The IANTD rec trimix course is flexible about mixes. GUE are not - and that too has some validity - avoiding confusion etc (with which I agree). Why then pick 30/30, not say 25/25 which gives a 150fsw MWD at 1.4 and an END that is not beyond people in the intermediate phase of their diving??

Chris.

Here you kind of point to a fundimental difference in philosophy in that GUE advocates standard mixes rather than "best mix". It does have many advantages but I can't really speak to the 30/30 question because I haven't used it all that much.

A lot of the divers I know prefer to dive the above wreck using a mix like 28/30. They just choose to cut back on the O2 a little mostly because of the cold water.

 

[MikeFerrara]

Maybe I missed it in all the confusion, MikeF. But what mix are you using for that dive?

I usually use 21/35 for a couple of reasons. One bing that depths of about 145 ft are possible inside and I'm ok with using 21/35 at that depth. Another is that I dive 21/35 often and I'm familiar with my schedules. Yet another is the fact that I often have it mixed already.

I like the idea of introducing it with the "overhead" of a lot of tech training too.

Some people don't ever want to go to170 or 200 but that doesn't mean that that helium won't ever offer an advantage for them.

To think that some aren't allowing penetration (or at least don't like it) at those depths I think is getting a little "Wennie-ish". If the arguement wasn't a good one, I'd say they're being overly silly in caution, but still, to think that one can't function at those relatively shallow depths isn't the real deal IMO.

"Ideally" yes,.......mandatory, well not so big a yes. In fact, to me, that's squarely a personal choice and should be left that way and not forced by a boat captain.

I don't know that they absolutely mandate it for this wreck but they certainly do for some others (deeper) and still others are by invitation only. They definately reserve the right to have some say in what kind of diving is going to take place off their boat.

Unless of course he doesn't mind if you don't have the "card" to prove you took the "training".

They will most certainly insist on a card.

 

[MikeFerrara]

For me personally, Most Definitely Yes.



I have no particular problems with an 'intro to Trimix' concept on general principle. However the foundation of all education is that the student is going to apply and extend the principles of what he has learned, which is why chrisch is spot-on when he says: "Why then pick 30/30, not say 25/25 which gives a 150fsw MWD at 1.4 and an END that is not beyond people in the intermediate phase of their diving??".

Particularly with its EAN36 no-deco tables klunge, 30/30 looks to me to be a niche application. There's nothing wrong with being a niche, but rather the philisophical appropriateness of teaching the exception before the rule.


-hh

I would agree that 30/30 is a niche gas. Too much O2 to ge very deep and much shallower and even lots of DIR divers would skip the helium. This class doesn't go to 150 though.

GUE dives and teaches the system that they choose. You could argue every little detail for ever but that's their system.

BTW, many of us don't care to use 25% O2 at 150 because we'd rather not dive at 1.4 ata PPO2 since we'll be finishing a dive like that up on 100% so we go easy on the O2 until then.

 

[cornfed]

Another Ad Homenium insult.

DID SOMEBODY SAY AD HOMINEM???

 

[MHK]

For me personally, Most Definitely Yes.



I have no particular problems with an 'intro to Trimix' concept on general principle. However the foundation of all education is that the student is going to apply and extend the principles of what he has learned, which is why chrisch is spot-on when he says: "Why then pick 30/30, not say 25/25 which gives a 150fsw MWD at 1.4 and an END that is not beyond people in the intermediate phase of their diving??".

Particularly with its EAN36 no-deco tables klunge, 30/30 looks to me to be a niche application. There's nothing wrong with being a niche, but rather the philisophical appropriateness of teaching the exception before the rule.


-hh

hh,

One of the many reasons that 30/30 mix was used is that for the target depths covered within the application of otherwise NDL limits the gas works strikingly similiar to the way that we convert a 32% to an air table.

Moreover, the complete idea of this class was to keep it RECREATIONAL. Once you start getting into the 150' range a whole set of different protocols come into play: decompression, gas switches, mandatory doubles etc. etc.. The true design and application of this class is tantamount to a deep diving and/or an advanced class. Helium is but one small tool in teaching divers [ that have no desire to do any sort of technical diving] how to more safely explore the deeper ranges of otherwise recreational limits..

Later

 

[DeepScuba]

MikeF:

I said........"I like the idea of introducing it with the "overhead" of a lot of tech training too."

When I meant to type.... WITHOUT the "overhead" of a lot......

My mistake, we agree.

When I was speaking of "mandatory" Helium use, it was at depths described, and NOT 230ft Doria dives etc. I mean the "personal" limit area of 100-140 or so. Maybe even up to 180ft. since I THINK some tech agencies are still OK with this.

 

[Dan Gibson]

How about you show up and do a dive with our group at Little River or Devils next weekend if you are cave certified? Those would be good dives for 30/30.

You are missing the point of the challenge. It has nothing to do with helium. I hope you don't think the rec triox is simply a way to get a card that permits a diver to use helium? The first part of the class will separate those that have the skills from those that don't. Those that can't will never see the helium during the class. I'm not talking about the simple drills run in DIR Fundamentals classes that most people don't do well first time around. I'm talking about performing to the required levels when failures and different scenarios are thrown at the diver. Add to that, situational awareness (that includes the whole team, not just each individual) must be excellent.

Try the 30/30. Your head certainly won't be less clear than on a nitrox mix. I don't know what you will experience in warmer waters and not working hard. I can tell you if you dive 40 degree water that is very dark and deep, it will provide more substantial results. I can also tell you that a working dive (ie high flow cave) around 100 feet will yield positive results.

I think HH has hit the nail on the head here with this.

For myself, I have a solution to this problem. I will simply obtain a couple of cylinders of UHP and mix up some of my own 30/30, and see what I think of it on a couple of 130' dives.

Comparisons will be easy to make, since I will also bring a tank filled with 30% Nitrox.

If I can discern a significant difference underwater, then I will concede that it makes sense in that range to use Helium, provided that the cost of doing so is reasonable (it probably will be for me, mixing my own.)

Since I expect to have a "real use" for He-based mixes this summer, assuming that the carrier planned to be sunk does come to Pensacola, the opportunity will present itself for this sort of experiment within a few months.

I'd even go buy a tank of the stuff at "commercial" rates to do this test earlier, but they seem to want to sell me several hundred dollars worth of training FIRST; as a consequence unless someone shows up with a tank of 'Mix (or will have one filled for me to use) I guess it'll have to wait until I have a reason for the tank leases....

(For those who issued "challenges" earlier, why not take the cheap way out and simply show up with a couple of bottles of 30/30 and go diving with me? If there's a case to be made for using it in the range of 100-130' in terms of mental clarity and such, I'll be the first one to agree - once I have some evidence that its significant.)

 

[Genesis]

So you do not accept my challenge to you to allow me to determine if the gas actually has application in my diving?

Ok. No problem. Let the record show that I even offered a boat trip in the bargain and was turned down - all over one lowly bottle of gas.

 

[Dan Gibson]

I think I'll have to exercise Rule No. 1. It just isn't worth the risk.

So you do not accept my challenge to you to allow me to determine if the gas actually has application in my diving?

Ok. No problem. Let the record show that I even offered a boat trip in the bargain and was turned down - all over one lowly bottle of gas.

 

[Genesis]

I think I'll have to exercise Rule No. 1. It just isn't worth the risk.

More name-calling. Reported.