Are there too many unnecessary steps to get normoxic trimix certified?

[tbone1004]

Redshift, why is that?

Regular trimix can be used as an advantage from day 1 allowing the divers to extend NDL's, or dive with comparably lower nitrogen loading for the same dive profiles. Advanced nitrox is levels over 40%, why would a diver need that until they are doing decompression? You don't get any significant NDL advantages from higher levels of nitrox at the shallower depths that they would be restricted to and while I agree that the math is obviously the same, until you are doing decompression there is no need for higher nitrox levels. That is why most instructors combine AN/DP into the same class. I think the agencies should be doing it as well, but it is unlikely from the recreational agencies.

 

[kensuf]

After that I'm torn on whether or not normoxic should be separate from hypoxic trimix because the procedures are largely the same but at the same time it's more of the depth/time of the hypoxic that makes it worthwhile of separating. Not in the discussion here though.

20 years ago I would have agreed that they didn't need to be separate. Now I believe differently. The main reason being that you can do normoxic dives with just one or two deco bottles, and descent on backgas (no travel gas!). But for a hypoxic dive you're going to have travel gas, and likely 3 (or more!) deco bottles/gas switches. Breaking trimix up into two courses with some time in between gives someone the opportunity to develop the muscle memory/skill to manage multiple bottles.

BTW -- some agencies allow helitrox to be combined with AN/DP. So someone could get out of AN/DP and be on helium for dives down to 150'.

 

[Redshift]

Redshift, why is that?

Regular trimix can be used as an advantage from day 1 allowing the divers to extend NDL's, or dive with comparably lower nitrogen loading for the same dive profiles. Advanced nitrox is levels over 40%, why would a diver need that until they are doing decompression? You don't get any significant NDL advantages from higher levels of nitrox at the shallower depths that they would be restricted to and while I agree that the math is obviously the same, until you are doing decompression there is no need for higher nitrox levels. That is why most instructors combine AN/DP into the same class. I think the agencies should be doing it as well, but it is unlikely from the recreational agencies.

I am not arguing the need to use mixes over 40% straight away (although divers going the rebreather way will need advanced nitrox even while not going into deco at first), I am arguing that there is no need separate the instruction, because it's the same! Dangers of oxygen, requirements for gear, CNS toxicity, OTUs, formulas... all the same for 30, 60 or 100%. The fact that it's split just means extra costs for students.

 

[boulderjohn]

With some of the agencies utilizing "many courses" each course is actually pretty short (2 days, 10 contact hours, 4 dives etc). Via of those agencies offering "one" course you'll find that course is generally much longer, like 5 days, 50 contact hours, and 10+ dives. Obviously price varies too. I think you need a certain critical mass of material to justify any particular course. E.g. advanced nitrox alone is short and quick but also pretty useless.

I am not arguing the need to use mixes over 40% straight away (although divers going the rebreather way will need advanced nitrox even while not going into deco at first), I am arguing that there is no need separate the instruction, because it's the same! Dangers of oxygen, requirements for gear, CNS toxicity, OTUs, formulas... all the same for 30, 60 or 100%. The fact that it's split just means extra costs for students.

I think the academic portions of the two courses are pretty much the same, so taking the advanced nitrox portion of the program repeats a lot of ground. The difference to me is in the physical skills required. Recreational nitrox courses these days usually don't require any dives. Once you strap the tank on your back with the correct mix, the dive you do is the same as the dive you would have done on air, except for the MOD and the different NDLs. The only reason to use higher levels of nitrox is for decompression, so you have added a new skill--carrying and switching to a deco bottle. You also need to have different equipment, including an O2-ready regulator. That is why some agencies, like TDI, usually teach the class in conjunction with a class like Decompression Procedures.

But not all agencies do it that way. UTD, GUE, and PADI blend the skills and training associated with advanced nitrox into the courses themselves--they have no equivalent of the AN class.

Some agencies also introduce helium much sooner. When I was with TDI, I was breathing helium as soon as the tech program started. I had already completed TDI AN/DP, but that was an unnecessary coincidence. I don't think there should be the big leap before starting to use helium associated with most agencies.

 

[PfcAJ]

After that I'm torn on whether or not normoxic should be separate from hypoxic trimix because the procedures are largely the same but at the same time it's more of the depth/time of the hypoxic that makes it worthwhile of separating. Not in the discussion here though.

The procedures are similar but you need a solid foundation in normoxic techniques (gas switching, deco procedures) before throwing more depth, time constraints, bottle rotations, hypoxic descent protocol, gas breaks, etc into the mix. Its too much.

 

[tbone1004]

AJ, that's where I do agree with the separation of trimix because what is required for a 300ft dive is much more than a 150ft dive despite the math and techniques being the same. It's way too much.

I think the ideal training progression would be as follows

Nitrox Diver-no basic class should be done without teaching nitrox imho.

AN/DP potentially normoxic if the student wants/needs it. That's the advantage of keeping it separate, you might need decompression but not helium.

Hypoxic on an as needed basis for expedition. I think GUE breaks it down pretty well with Rec1, Fundies, Tech 1/Tech 2

 

[PfcAJ]

Hypoxic on an as needed basis for expedition. I think GUE breaks it down pretty well with Rec1, Fundies, Tech 1/Tech 2

I think GUE's method is good. Even their T2 ticket is a 15/55 card and they put 12% on your card only after 25 t2 dives.

 

[alfred1]

Thank you all for your feedback

 

[waterpirate]

I am not sure if I am board with an/dp and normoxic as one class. I would want to see more time/dives executing those skills with 20% he , before the leap to 200fsw and a minimum of 2 bottles? Anybody else feel that way?
YMMV
Eric

 

[rhwestfall]

its 150 for my classes.... I was looking for He to take the fog off. I've had some interesting experiences at 110, yet other times 130 was fine (so I think). It was a means to achieve He benefits, and see it as a smart option....