What goes into a Trimix course?

[CAPTAIN SINBAD]

What does a Trimix class typically consist of? I am thinking by the time divers reach Trimix level they would be proficient with valve drills, general buoyancy, air sharing and gas switches etc. Additional bottle handling/ passing may need one or two pool sessions. Can anyone enlighten me on the structure of their Trimix class? What did you guys do on each day?

Thanks.

 

[KevinNM]

GUE does trimix in Tech 1, so all that stuff is introduced there.

 

[CAPTAIN SINBAD]

GUE does trimix in Tech 1, so all that stuff is introduced there.

Yes. I am somewhat familiar with the GUE/UTD way of doing things. Their training is very detail oriented annnd heavy on skill development. Expectations are high so a lot of time is spent in the pool. I was wondering how would a mainstream Trimix course differ from the GUE/UTD Tech 2 course? I guess it would depend on instructor but there would still be a skeleton that each instructor would try to build on.

 

[DevonDiver]

I am thinking by the time divers reach Trimix level they would be proficient with...

*choked on my coffee*

 

[boulderjohn]

Academically, there are significant issues with gas planning when you get to those depths and start working with more gases and more cylinders. If you are doing the CUE/UTD approach and only using standard gases, there is a lot of decision making you don't have to do. You just go across town to the nearest full service dive shop and dial up the appropriate standard gas. If you are diving in places where there is not a full service dive shop on every corner, things get a little more complicated. You have to plan mixes carefully based upon what you can get with the supplies you have, meaning you have to make decisions about MOD, END, etc. There is the conflicting evidence related to the supposed helium penalty for decompression. There is the question about deep stops to consider. Planning for and using a travel gas is a consideration. Carrying 3-4 deco bottles is different from carrying 2.

But in reality, most of the real learning comes in the earlier classes, so it should not take as long as it takes in some programs.

When I was with UTD, I was at the rough equivalent of a TDI normoxic trimix class in my training. When I switched over to TDI for that certification, I had to do regular trimix (which was mostly a repeat) and then Advanced Trimix. It took me a few weeks to become full trimix certified. If I had stayed with UTD, I would have been required to go through four more classes PLUS a total of 90 additional experience dives (20 of them experience dives between 200-250 feet in addition to the training dives) at different levels in order to get the same certification level. Additionally, I would not be allowed to do the training on my own--I would have had to have a training partner at the same level for all classes. My honest best estimate is that it would have taken me 7 years. I thought about it for a long time. 7 years. A few weeks. 7 years. A few weeks. 7 years. A few weeks. I made the switch.

 

[Diver0001]

I did TDI and I found it very straightforward. The book is subjective at times but highly focused on the practical application, which made the things I needed to learn easy to spot as I was reading. I only needed to read the book once but I already knew most of the theory and I had been making technical Nitrox dives for a number of years before I did Trimix. The in-water part was a breeze in my case.

I was, however, surprised that not all of the students found the in water part of the course easy. Like you I had assumed that everyone would basically know what they were doing by that point, but this was not the case. One of the divers in particular was an experienced cave diver but had little (no) experience with working in mid-water without a visual reference to judge his buoyancy control. At times he looked like a bit of a beginner because while he could dive just fine, he found it hard to do without being able to orientate himself to the bottom, which is a fact of life where I dive.

Another of the students was training to be a TDI instructor but his communication was so bad (passive and unclear) that I didn't think his chances of ever becoming an instructor were very good. For example, during one dive he started feeling light headed and wanted to abort the dive but instead of communicating that he had a problem and to abort, he just took off..... I chased him down to help him but his action lead to the team getting off plan and ultimately having to split up.

Those are things I never thought I'd see in Trimix class but I guess instructors must have to deal with remedial training needs quite a lot.

R..

 

[tbone1004]

theoretically, and take this with a heavy grain of salt, there isn't actually that much to teach in a trimix course. We'll use TDI's advanced trimix because I don't believe in normoxic trimix
link to standards here for those that are curious
https://www.tdisdi.com/wp-content/u... Diver Standards_13_Advanced_Trimix_Diver.pdf

4 dives, minimum 100 minutes, 2 recommended to be below 230ft.

Above water:

Can you do nitrox math for MOD and EAD? If you can do it with nitrox, you can do it with trimix. Change EAD to END, which isn't actually changing anything, and you're good. The math is as simple as how much O2 do I need/want, use the exact same formula for how much N2 you need/want, and the balance is He. If you do standard mixes, it's that much easier since you are always calibrating back to EAN32.

Can you analyze a tank? Now you have another readout on the display for He.

Can do you dive planning? Great, dive planning is still dive planning. Deco is a little more complicated, but with planning software the hard work is done for you there. Gas management is more critical because it goes a lot faster down there, but it's the same math. You do actually need to learn a bit about how He can change decompression, but that can be done in a book, at home, and if you get lost, read it again or call someone who is a subject matter expert. They exist.

There are a lot of physiology things to go over, but I'm willing to be quite a bit that the vast majority of trimix instructors don't actually understand what's going on, they're just repeating it back out of the book. No different than most technical instructors with deco theory, CCR instructors on how the units actually work, etc etc. It's not a problem, it's just you can get the same information out of the books, and most instructors aren't going to be that valuable in the learning process for the physiological aspects. *This is not a critique, most scuba instructors are not physiologists, engineers, etc etc so they shouldn't be expected to be subject matter experts. Their job is to teach you how to dive properly, not make you a subject matter expert in physiology or engineering*. Basically you need to know that trimix can be dangerous because of the depth increasing gas density which can kill you *cue David Shaw*. Lower density of helium makes you cold, wear good undies. ICD is a real thing, so be careful when planning your deco and travel mix gases.

After those, you're ready to get in the water. Realistically can be taught to people that are qualified to actually take this in maybe 2 hours? About 20 minutes to verify knowledge if they did their homework.

In water:

Can you do bottle handling? You damn well should be able to since you would have to have AN/DP to get in the course in the first place. Now you have at least 3 bottles to deal with. Travel mix, 1 or 2 deco mix, and maybe bottom stage that's rough. Bottle handling is bottle handling. If you can do one bottle switch properly, and if you're in backmount, just subscribe to the GUE equipment configuration and don't try to reinvent the wheel. If in sidemount, I personally think you're an idiot for diving sidemount in open water, but to each his own. If in a cave, you're lucky because you can drop all that stuff off fairly quickly.

After that you should have done everything else including blue water decompression from a lift back or SMB in AN/DP.

what @Diver0001 said about cave divers struggling in blue water is real, I know I do. I much prefer my visual reference to blue water hangs. I can do it, but I don't like it. I'm ok on an anchor line or with a knotted reel, but much prefer deco in caves, much easier.

My personal belief on the subject is going to offend people, and I just deleted it. GUE has the right course progression imho, that should say enough. If you have your sh!t together by the time you get in, with the rest of the world's view on trimix training, there shouldn't be anything skills wise that you learn. You'll learn some physiology and deco points that are different from nitrox diving, but you can learn that from a book. There are "tricks" that you can only learn from a good mentor, and that alone is worth getting time with a good instructor who does this stuff on a regular basis, but don't expect to learn a whole lot of meaningful skills or anything because frankly, there isn't anything skills wise about doing a full trimix dive vs. a big nitrox dive. The biggest difference is everything that can go wrong is amplified because of the depth.

 

[LiteHedded]

there's GUE tech 1 and 2 and there's everything else. they are WORLDS apart

 

[CAPTAIN SINBAD]

Great responses everyone. Very enlightening. I am a bit unclear about the notion that not much in water skill is added at the Trimix level. I am proficient in the use of a single-AL40. I can pass that around without losing buoyancy and trim and do gas switches with is. When you change that with an AL-80 then things change. I can do gas switches since they are the same but I can not pass the tank without losing buoyancy and shooting up. In order for me to dive with a single AL-80 instead of an AL-40 I will have to drill the bottle passing with an AL-80 for quite some time. Now keep in mind that we have not added any additional bottle here. We have only went from AL-40 to AL-80 and one fundamental skill (pass the bottle to your buddy) has changed significantly where it is demanding additional pool time. I can only imagine that with two bottles things would be more difficult. How is it then that Trimix courses do not have sufficient pool time built into their training? GUE and UTD courses do but when I see 4 day long Trimix courses by other agencies then I am thinking if sufficient time is being spent on drilling the bottle handling and other stuff.

 

[tbone1004]

three t
First: al80's are only .6lbs more negative than an al40 when full.... you shouldn't lose buoyancy from half a pound, especially on OC. If the bottle is not fully empty/super floaty, it should be very close to neutral which should negate any difference in passing it around.
Second, and arguably more importantly, who says that you have to use an al80 for trimix diving and why you can't for nitrox diving? The last cave trip, if you follow the need for 1.5x gas for deco, I needed an AL80 for decompression and I was only diving to 100ft. Granted it was for 3 hours, but an AL40 is not large enough for what I was doing.
Third: said dives required the use of 2 al80's for bottom stage bottles, and the al80 of O2 for decompression. 3 bottles to move around, and since I was in a cave that has a restriction to the entrance after the deco room, the bottles had to stay in place. From there, they get moved to my butt rails and chill out, but all of the bottle handling is there.

Had that been conducted like a "full trimix dive" or actually been one in a similar profile cave, one of those bottles would/could have been a bottom stage, another would have been my travel gas/deep deco, so either EAN32, 35/25, 50/50 or whatever you choose, and the other would have been O2. Bottom stage handling doesn't change, and you drop off O2 in the deco room, travel mix could have been EAN40 because of the cave profile so would have been dropped off at the tie in point at 80 ish ft. Return of dive would have you pick up and verify etc etc the deep deco mix and switch off of back gas for the first deco stops. Up through the restriction and into the deco room, you conduct a normal gas switch procedure onto backgas *assuming bottom mix is not hypoxic at that depth* and done a gas switch to the O2 bottle. If diving a wicked hypoxic mix like 12/70 or something, you may want to leave the travel gas up front for air breaks instead of switching over to 12/70 because of ICD and the fact that it's borderline for PO2 if you are on your 10ft stop I'm not sure how that is taught in backmount.

The dive itself wouldn't really have been any different from a bottle switching standpoint, the only difference would have been the use of a deep deco bottle/travel gas.

So it really all depends on the dive profiles you are currently doing and the ones you want to do. For me to go from 3+hr long nitrox dives at 100ft with multiple stages and then go over to full trimix, there are no new skills. I'm already doing multiple stage handling, so the only difference is the addition of He to the gas planning and dive planning *from both a physiological and logistics standpoint*.
If however you are coming from a training background where the only "extra" bottle you are carrying is a 30 or 40 of O2, then yeah, the learning curve is going to be steep because bottle handling isn't something you are familiar with, especially in OW where you aren't staging that deco bottle and aren't used to moving it around.

some good videos from ISE on how they teach multi stage handling.