Recreational Trimix Diver course with Techs Mex Divers, Part I

[jtivat]

Somehow I am not making myself clear. I do not dive in doubles, nor will I dive in doubles in the foreseeable future. What I do is buy singles gear from people who upgrade to doubles themselves. There will probably be an upgrade to Y Valves between here and August, but that is a story for another paycheque or two.

I just assumed when I read Trimix in the title of the class that there would be in water skills. I see people going to warm waters to do tech classes all the time and it makes no since to me. Skills like shooting a bag, valve drills, putting stages on and off and OOA should all be done with dry gloves and a dry suit if that is how you will be doing the real dives. My first trimix class had three other students they all put on 3mm glove instead of there dry gloves for the shallow practice dives. They had a hard time when we got to Gilboa in 38f degree water at 120?

 

[Reg Braithwaite]

I just assumed when I read Trimix in the title of the class that there would be in water skills.

A reasonable assumption, however the word "Recreational" is also in the title alongside "Trimix," which makes the whole thing a ball of confusion! If you want a comparable conundrum, UTD offers a Ratio Deco class that is purely theoretical, I do not believe there are any dives at all, not even experience dives. One might assume that with the word "Deco" in the title in-water skills would be involved, but such an assumption would be incorrect.

This feels like Deja Vu all over again, but here goes: Plain Jane Recreational Trimix is an IANTD course that purports to teach minimal trimix mix selection and nothing more. There is absolutely zero certification of any skill whatsoever. For example, although it teaches how to select a best mix for minimal deco dives to 130', it doesn't actually certify you to execute such dives, you may only dive to a certification level you obtain from another course, one that presumably teaches the actual skills you need in the environment where you will use them.

For example, if a student takes a certain agency's "F" course, she may graduate with a card certifying her to dive EAN32 to a depth of 100' and no more. If she then takes IANTD Rec. Trimix, she is still only certified to dive to a depth of 100', she has gained nothing except for the option to execute the dives she has already been trained to do in Trimix if she chooses. She is not certified to physically dive to 130' even though she has demonstrated the skill to plan the mix and gas consumption requirements for such a dive.

Another example of the limitations of the course is that it does not teach any form of deco planning that you don't already know how to do. Some of the exercises require you to demonstrate using EAD to calculate no-stop limits based on IANTD's air diving tables. A single table is provided for 32/15 mix, and there is an exam question requiring you to consult this table instead of using EAD. But these are skills you already know if you have the prerequisite Nitrox certification. Nothing new is presented about deep stops, one minute ascents, minimal deco, nothing. You must obtain training elsewhere on how to conduct the dives you wish to perform.

I appreciate where you are going with thinking that the course would benefit from in-water skills practiced in the environment where the student will dive. I would suggest that you are advocating an integrated approach whereas IANTD in this case are offering an a'la carte item. You can mix and match Recreational Trimix with the in-water dive training that you feel is most appropriate.

If you are saying that the course in and of itself is useless for training me or anyone else to perform a certain dive, we are in "violent agreement." The course provides a certain type of very specialized and limited knowledge, but it is not a complete training program and cannot stand alone.

 

[rjack321]

I don't want to get into a discussion about what other people are going to dive. I've talked to people about this dive, I've had expressions of interest in doing a minimal deco dive on this wreck, but nobody has plunked down money to reserve a seat on the boat yet, much less analyzed gas with me. We'll see what they do when the time comes.

For now, this is a tool in my tool box.

Well you've expressed an interest in GUE diving in the past (which is great) and generally seem like your quite mindful of your buddies and issues such as that (i.e. the Y valve, maybe not a great choice but better than some alternatives). But paradoxically you went to the tropics to get a He card. The class for which didn't expect you to have any in-water skills beyond what a conventional AOW/deep diver specialty might expect at 130ft. As a GUE and "UTD" trained diver, I would dive 32% down to 90-100ft with you like I probably would with any other AOW grad.

But once you start adding He into the mix, your 3 mins of shallow stops, the absence of doubles at depth and in pretty cold water, not being trained in the conditions your plan to dive in (drysuit, drygloves etc), diving to a ppO2 of 1.5, all of those factors start to make me question whether a 120ft dive on helium with a 6 or 7 minute (minimum) midwater ascent is a good plan.

I'm sure the class and the dives were a great experience, but with <100 dives I would say that you're just barely getting your feet wet. And that remembering that you are only qualified to dive in conditions similar to those in which you trained in (an axiom which goes back to OW class) might be prudent.

I would encourage you to find some local buddies who you can progress through your training with together. It really is way more about the training and the buddies. Good physical and mental skills for yourself and your buddies are really paramount to having fun with challenging diving, far moreso than gas choices.

Take care,
RJ

 

[Kevrumbo]

[Hijack by rjack alert]

Instead of blaming obtuse ICD principles you could also say that high N2 gases at depth (e.g. 70-120ft) don't really enhance total offgassing since the N2 loading in that range ends up being significant. N2 that you eventually have to eliminate later. Better to keep the low solubility He %age high. None of which is really relevant to the OP's 120ft, ~10min MDL dive.

On the contrary, it could have been very relevant to Oliver the Instructor --doing gas switches to eanx38 at or above MOD of 32m/107' -- AND if he was diving Trimix. The chances of ICD are slight in this instance, but it still is a bad practice to execute IMO (and the point is moot anyway because Reg could not relate or recall the content of Oliver's backgas in a later post from the OP).

So Rumbo following RBW's advice I take it you don't do backgas breaks, at e.g. the 30ft stop and every 10-15mins during the O2 time?

No I don't do backgas breaks if I was using RGBM Deco Tables and NAUI-tec Mixes. Yes I do backgas breaks --off from Oxygen or eanx50; or in lieu of a hypoxic backgas mix, gas break on the last previous and deeper MOD deco gas-- if I was using Ratio Deco.

Rumbo you are doing 1:4 RD profiles (300ft)??

On planning spreadsheet only for now, but doing a lot of assorted AL40's/63/80 tank practice swapping with four deco bottles plus a stage tank while juggling an X-Scooter. . .

 

[Reg Braithwaite]

But once you start adding He into the mix, your 3 mins of shallow stops, the absence of doubles at depth and in pretty cold water, not being trained in the conditions your plan to dive in (drysuit, drygloves etc), diving to a ppO2 of 1.5, all of those factors start to make me question whether a 120ft dive on helium with a 6 or 7 minute (minimum) midwater ascent is a good plan.

I really don't feel like repeating myself at length for the fourth or fifth time, RJ. I have not said at any time that taking a Recreational Trimix course while I happened to be on vacation with my family is anything except some information and knowledge that form a very small and nearly insignificant part of an overall plan to do a certain dive five months from now.

A month or so ago I went out and ordered Mark Powell's "Deco for Divers" book. Why did I buy and read this book? Because having reviewed what little a certain agency has published on the subject of decompression, I wanted to know more about the theories and basis for the practices that the agency teaches.

Of course, the book comes with zero in-water skills. So we could have exactly the same conversation about it. What's up with looking ahead to a 120' dive on He with a six or seven minute midwater ascent having just read that book?

This course is like the book. It's a source of just one piece of knowledge, nothing more. Try taking it at that and not imbuing it with significance it doesn't have.

 

[grazie42]

But once you start adding He into the mix, your 3 mins of shallow stops, the absence of doubles at depth and in pretty cold water, not being trained in the conditions your plan to dive in (drysuit, drygloves etc), diving to a ppO2 of 1.5, all of those factors start to make me question whether a 120ft dive on helium with a 6 or 7 minute (minimum) midwater ascent is a good plan.

I sort of disagree...
I did my mix-courses in Florida in a wetsuit, a long way from the cold local waters. It gave me more in-water time on the skills particular to that course and with the instructor than I would have had on a local course. When I got back I started slow to determine how the local conditions effect me and I had all the time in the world to slowly work my way back up(down?) to the level I trained at during and after the course in Florida. I already knew how to dive a drysuit, and all that but the only way to find out how you feel after 30 mins of deco in 4C water is to do the dive (after having done 15,20,25 mins before)...

I did my Mod 1 for my RB in local conditions but I figure that by the time at the end of this year (hopefully) when I have 50hrs on the unit, that I will either know how to dive it in cold water or I wont make it that far and so will likely take Mod2/3 (serious deco) in the red sea or somewhere else where its warm...

 

[Kevrumbo]

Did all my mix courses and advanced wreck penetration in the Philippines and The Big Island, and probably will take the Pelagian RB in Thailand --for exactly the same reasons: warm water and benign tropical weather, less physiological stress for a beginner. (As it turns out, I do most of my technical dives overseas in tropical locales anyway. . .)

 

[Reg Braithwaite]

So what mix(s) are you certified to use?

I just received my certification card. It reads:

This individual is qualified to the level of Recreational Trimix Diver
Max Depth 130 FSW / 39 MSW

It doesn't say anything about the specific mixes permitted. On the other hand, the course is extremely specific about what it purports to train me to do: Select hyperoxic mixes with the appropriate MOD and an END of 40 FSW to 80 FSW and conduct appropriate gas planning for backgas-only dives with same.

 

[Kevrumbo]

The card gives you some latitude, but of course stay within your training boundary.

btw, I used to get the "chokes" after repetitive NDL Hyperoxic Trimix dives, so now I always clean-up with Oxygen on the last dive of the series. Recommend you get training in advanced nitrox so you may have that option for an O2 fill. . .