IANTD offers a recreational trimix course which mates up pretty well with deeper NDL dives. Remember, NDL has nothing to do with depth. You can do a NDL dive to 140, 150, etc. The definition of 'tech' diving isn't really depth related either.
Sorry, think you've got it wrong here. Although Tech is usually a reference to overhead environment, recreational diving is defined as no-stop diving to a depth of no more than 40 meters with most mainstream agencies (Apart from BSAC which operates with 50 meters and deco - which in my book is tech, but that's a different discussion). So maybe a NDL dive to 150 feet would not fall into the tech category by default, but it would fall outside of the recreational diving category, so make of it what you will.
Most have adopted the term 'overhead environment' to signify technical diving in most cases. While deep can cause decompression obligation, which would be considered technical under this definition, depth along with time is what puts you there, not depth by itself. Performing a normal slow ascent with He is not dangerous. The problem stems from the fact that many divers ascend too quickly even on air or nitrox. They get away with it most of the time. This 'most of the time' would not be as forgiving with helium, since He offgasses quicker than other inert gasses. The average recreational diver wasn't deemed able to handle Nitrox many years ago either. Trimix to recreational depths (just a squirt is all it takes to eliminate narcosis), is a great tool for divers that want to do dives a the deep end of their NDL abilities, perform work (video etc), and do so with a clear head.
Maybe so, if you are doing 150ft dives as NDL's - But since 5 minute bottom time is on the low side to do any work, I kind of assumed we were discussing the depth limits of the mainstream recreational agencies when we were discussing recreational diving. I totally agree that a normal slow ascent with helium is not dangerous. But pop down to an average tourist dive centre, and see how many recreational divers do a normal slow ascent.
Divers who are competent enough to go down the tech route would probably be totally safe with recreational trimix, but these divers tend to go down the tech route. If your buoyancy is not good enough to hold formal deco stops, I would suggest helium might not be the best idea in the world.
How is that you can make a comment like, "narcosis is not a problem within recreational diving limits."? Are you an authority on dive related incidents? Narcosis is a factor in incidents and accidents. It often times can be the dissappearing evidence after the fact.
Yes, narcosis is indeed a factor, and if all divers dived recreational trimix, I dare say the outcome of a lot of the incidents might have been fatal. Or maybe some incidents would never have happened, but some that hasn't happened might have. It would be interesting to get the views of a dive doc in regards to this matter - Given that a lot of the chamber rides around the world are due to rapid uncontrolled ascents on air or nitrox, what do you reckon the outcome would be if all these were on trimix?
Also, how can you say that recreational trimix is one of the courses aimed at NDL that makes no sense and say that normoxic trimix does? You do not understand trimix. Recreational trimix is normoxic trimix by definition of the gas and curriculem. Normoxic Trimix courses assume you have already taken decompression training. The trimix training is identical to recreational trimix. If you don't believe, I will show you the materials for the two courses. I have taken all of them. Which of them have you taken to be such a knowledgeable source on any of this? BTW, you can use what you learned in Normoxic trimix on dives in the NDL ranges. We do it all the time.
Because a recreational dive tends to be shallower than 30 meters for the majority of divers - A few do 40 meters, and it starts to make sense to dive trimix, but then it starts making sense to add in 10-15 minutes of stops, and actually have time to look around as well.
I'm not sure what your point is here?? Are you backing my line that the antagonists got it wrong and that you now have it wrong about trimix?
No, I have never argued that trimix hasn't got a purpose, but not in shallow diving. Trimix is a deep(ish) gas - Nitrox is a shallow gas, so I'm saying the antagonists had it wrong, and one ought to use the right gas for the dive in question.
How about 35 to 40 meters? You say risk management like putting 10% He in a tank is going to somehow raise the risk by some huge degree. Hardly. I agree, trimix is no goal. Safe diving is.
As I said - At those depths it's starting to make sense if you tend to get put out by mild narcosis. Each to their own. I would use mix if I was doing something vaguely complicated, like penetration, but not for a nice dive over the reef looking at the pretty fishes.
Right. And my statement was that trimix does this and one more thing, reduce narcosis. Simple true statement. You sound foolish attacking that simple true statement with uneducated(untrained) responses.
You're clearly not reading what I'm saying. You made a statement which pretty much said that there was no point in Nitrox - Trimix is the way to go. That is a false statement - You have the greatest benefit of Nitrox in fairly shallow water - You have the greatest benefit of Trimix in fairly deep water. See my point?
The question of your education was not pointed at anything other than that related to diving. I'm not sure how I've been offensive, but you borderline on it. Try to add a little humor to your life. You might actually be a little less annoying.
That's funny, because it came across as if you were relating it to your comment about being able to read a simple sentence.
The reality of the matter however, is that there is not an issue with my education. Or yours, I'm sure - Your profile looks fairly impressive. What it an issue though, is your arrogance. I've never disagreed that Trimix has a purpose. You might not agree, but I'm telling you, your original post came across as if you meant people should forget about Nitrox and go for Trimix instead (and your subsequent posts came across as if someone disagreed with you, they were stupid). To use Trimix safely requires CONSIDERABLY more in-water time than using Nitrox, so by throwing out the trimix comment, not only did you come across as a little bit of a cyberdiver with big words and little knowledge (although I understand this is not the case..) but you also potentially made divers with insufficient dive experience to use trimix safely think that they ought to go and do a trimix course instead of the nitrox course they were considering.
So in the spirit of making peace, I will agree with you that on dives to the deeper end of the recreational depths, for divers with sufficient experience and skill to do it safely, trimix is not a bad idea. (Be that on an NDL dive or a deco dive). But let's be clear, we're talking about maybe the top 5% of the diving population in terms of skill and knowledge here.