What's the deal with the "Advanced Nitrox" certification?

[Reg Braithwaite]

I presume by "recreational trimix" is meant TMX 30/30.

One agency, GUE, teaches the use of two standard gasses, EAN32 and 30/30 for no decompression dives. IANTD teaches a "best mix" approach and sells two different no-decompression Trimix tables: 28/25 (which they promote as covering 30/30), and 32/15. Or you can cut your own tables and dive 21/35 or 25/25 or anything else that you deem appropriate. Although I have not purchased their training materials, I have heard anecdotal evidence that another agency teaches 25/25 as one of its standard gasses for no-decompression dives, and I have also heard it is easy to mix.

So I get the impression there are a variety of opinions about the use of trimix and the specific composition for recreational dives.

Advanced Nitrox is normally the first tech course in any sequence. It is the class where the instructor gets to meet the new students and work on their weighting, trim, buoyancy control, sculling, finning, and what not. So normally ordinary 100 ft dives are done with EAN 50 used as a "clean up" mix in simulated decompression.

I purchased TDI's "A Guide to Advanced Nitrox Diving," which I understand is their manual for their course. Nowhere in it do they mention working on fundamentals such as weighting, trim, buoyancy control, sculling, finning, and what not. Other than mentioning the use of enriched mixes for accelerated deco, they don't cover that subject at all. It's mostly a review of what is covered in the normal nitrox course with some extra detail around the equipment and procedures for handling mixtures above EAN40.

I value improving fundamental skills, and prior to reading your post I assumed the best way to work with an instructor on my fundamentals was in a course specifically targeting fundamentals, such DIR-F or NAUI Intro to Tech. Which is why I have made a commitment to taking a fundamentals course that doesn't cover the use of any gasses other than Nitrox mixtures under EAN40.

My thinking was that a fundamentals course would address the fundamentals and a gas course would address the use of gas, so I have pursued these things separately. If there is an instructor in my area who uses either Advanced Nitrox or Recreational trimix as an excuse to cover fundamental skills, that would be good to know.

 

[nereas]

Like I said, you need to speak with individual instructors in your neighborhood. That is indeed step one.

I would start by visiting your closest scuba stores and asking them about tech (deco & trimix) training.

If that does not provide any tech instructors, then I would turn to internet sources.

If you need to travel to get the training, Hawaii is famous for their nice warm waters and concentrated tech courses.

Besides Hawaii, there are also tech communities in Florida, Texas, and California. Of these 3, Florida has the warmest waters.

The instructor can tell you if he/she uses the Advanced Nitrox course to cover buoyancy and trim, and whether it is combined with stage deco as well.

 

[grazie42]

I purchased TDI's "A Guide to Advanced Nitrox Diving," which I understand is their manual for their course. Nowhere in it do they mention working on fundamentals such as weighting, trim, buoyancy control, sculling, finning, and what not. Other than mentioning the use of enriched mixes for accelerated deco, they don't cover that subject at all. It's mostly a review of what is covered in the normal nitrox course with some extra detail around the equipment and procedures for handling mixtures above EAN40.

I value improving fundamental skills, and prior to reading your post I assumed the best way to work with an instructor on my fundamentals was in a course specifically targeting fundamentals, such DIR-F or NAUI Intro to Tech. Which is why I have made a commitment to taking a fundamentals course that doesn't cover the use of any gasses other than Nitrox mixtures under EAN40.

My thinking was that a fundamentals course would address the fundamentals and a gas course would address the use of gas, so I have pursued these things separately. If there is an instructor in my area who uses either Advanced Nitrox or Recreational trimix as an excuse to cover fundamental skills, that would be good to know.

While a gue-f will certainly focus on the "fundamentals" I think you will find that adv. nitrox/tmx will as well (with the caveat that it is instructor dependent). The reason being that those courses are the "intro to tech" for those agencies (tdi/iantd)...My own personal experience (with IANTD) was that we certainly spent quite a bit of time working on it (and it was a "debriefing point" on every dive)...

If there is one negative with the agency materials (from IANTD/TDI) that I´ve seen, it is that they don´t really do the courses that are taught justice and most instructors supplement these with material of their own. This isn´t really a put-down on those agencies, just an argument for you to talk to an instructor to see what´s really on "the inside of the tin" because the "label" doesent do it justice, imo...

I think you´re at the stage now in your research process where you know enough about the generalities to get down to the specifics. Start researching instructors and talk to the ones that "stand out", see what they suggest for you...if you don´t just "want a card"(Im not suggesting that you do), then Im sure you can find some way to get the instruction you want out of people, even if they aren´t "teaching a course"...a sort of mentoring approach...

 

[orange_diver]

has anyone corrolated this to diving?

by experience, yes, many have. it really is MUCH easier to breathe at depth.

 

[orange_diver]

As Howard has said, I also see no use in "recreational trimix."

I presume by "recreational trimix" is meant TMX 30/30. I find that this mix works better for deco in the range of 140 to 70 ft than as a back-gas mix. I don't know why some recent agencies advocate using this as a back-gas, unless it is specifically for diving in the range of 100 to 140 ft. I see no benefit in it for dives shallower than 100 ft. I know that anecdotal benefits are broadcast, however the cast of characters who subscribe to these kind of agencies will believe anything they are told to believe from the top of the agency, unfortunately.

please do the math on that. 30/30 would give you a PPO2 of almost 1.6 at 140'. it's recommended to keep the MOD at 100' for 30/30. That's why some like 25/25 as it allows for a MOD of 130'.

This kind of person makes a very poor diving buddy because (1) they often cannot resist criticizing everything you do and (2) they further cannot explain why they are doing what they themselves do.

yeah, we clearly don't know what depths our gases should be used and can't explain why.

 

[ComputerJoe]

I agree that narcosis is extremely subjective and the degree you are narced will vary from dive to dive. Hal Watts has his 7 step deep air class that I will take if I ever get the opportunity.

I believe that to judge your level of narcosis on air versus Trimix you need to find out how much more clarity you gain back after being under the inluence, like asking a sober person how drunk that other one is. Going from trimix to air would be to as the drunk how drunk he is.

 

[ianr33]

please do the math on that. 30/30 would give you a PPO2 of almost 1.6 at 140'. it's recommended to keep the MOD at 100' for 30/30. :

If you check some of Nereas' posts you will see he often advocates a pO2 of 1.6 on the bottom section of a dive.

He can do whatever he wants but I wish he would not advise new(er) divers to do this.No agency will teach it.

 

[Reg Braithwaite]

please do the math on that. 30/30 would give you a PPO2 of almost 1.6 at 140'. it's recommended to keep the MOD at 100' for 30/30. That's why some like 25/25 as it allows for a MOD of 130'.

A few people have pointed out that He is expensive. From my arm chair, I would think that it makes zero sense to pay big money for a trimix fill on an NDL dive and then flirt with Ox-Tox. If it isn't conservative, it isn't my idea of recreation.

 

[battles2a5]

If you check some of Nereas' posts you will see he often advocates a pO2 of 1.6 on the bottom section of a dive.

He can do whatever he wants but I wish he would not advise new(er) divers to do this.No agency will teach it.

If you check his posts, you will clearly see that he has no idea what he is talking about. He probably read somewhere that someone uses 30/30 as an intermediate deco gas in those depth ranges and regurgitated it on this thread.

Reg- you are right, you don't want to risk CNS with ANY gas. You chances of surviving mild narcosis at 140fsw is MUCH greater than surviving a O2-tox event. The best way to avoid both is to just plan the dive correctly, which is something that Nereas cannot help you with.

 

[Blackwood]

IANTD teaches a "best mix" approach and sells two different no-decompression Trimix tables: 28/25 (which they promote as covering 30/30), and 32/15.

If IANTD sells 28/25 as covering 30/30, then I must conclude (contrary to what I was taught... by IANTD) that the tolerance on oxygen is +/-2%, and thus those two gases can be identical (30/20).

I'd love to get a hold of those tables and see how much the deco varies.

(Note, I am not advocating diving any table other than the exact one for which your analyzed mix calls for).