Recreational Trimix Diver course with Techs Mex Divers, Part I

[Reg Braithwaite]

I just returned from a trip to lovely Cozumel. Amongst all the family and diving activities, I squeezed in enough time (barely) to complete IANTD's Recreational Trimix Diver with Oliver Robertson of Techs Mex Divers. As the literature says:

This program is designed to provide recreational divers with a breathing medium for extending their dives to deeper sport diving depths without any narcosis. By adding helium and establishing Equivalent Narcotic Depths (END) between 40 to 80 fsw (12 to 24 msw), the divers will not feel the effect of narcosis. The diver may elect to dive the "mix" on tables or computers. The IANTD Recreational Trimix Diver qualification may be taught as a single program or combined with a variety of the IANTD Advanced or Specialty Diver Programs.

(This course is a bit of an odd duck. TDI, IANTD, and NAUI all have a fairly standard progression into technical diving that typically starts with a course like Advanced Nitrox that would include a lot of in-water skills development and learning to dive a technical rig of one sort or another. IANTD has another course called Advanced Recreational Trimix course that features in-water skills and up to fifteen minutes of deco with a single deco bottle. Recreational Trimix, however, isn't really a technical course, it's a recreational course. It qualifies you to dive trimix to your existing depth training or a maximum of 130 feet.)

After doing a little research, I got in touch with Oliver at Techs Mex and asked about taking Recreational Trimix. Via an exchange of emails, he queried me about my aims and experience and agreed to teach me the course one on one subject to my demonstrating sufficient in-water skills. He explained that he normally required at least two students to deliver the course at the advertised priced, but waived the usual one-on-one premium for me.

The course is typically two full days. The first is a long day of paperwork and orientation, followed by the presentation of the course materials. The second day consists of two dives, a written examination, and then the instructor-student review and sign-off. If the instructor is not satisfied with the two dives, he may demand two additional dives (for an extra fee) wherein in-water skills are taught. Oliver explained that for this course, the dives were experience dives rather than full instructional dives, and I was expected to arrives with a certain basic level of diving competency.

My trip to Coz was part of a family vacation, and taking two full days was not an option. Oliver agreed to a very loose schedule of evening course-work, morning dives, and following up with the exam and review later. I paid my fees by PayPal and booked my vacation.

As agreed, I showed up last Sunday evening at his place in San Miguel de Cozumel. He and his wife Janie operate Las Lunas Inn, a B&B catering to divers and other outdoorsy adventurous folks. I didn't stay there this time, but it looked clean and inviting. We did the paperwork for the course and got through twenty slides or so before breaking for the evening and I grabbed a taxi back to by hotel.

The next afternoon I was able to get to his place at three and we sat down and pushed through the material, finishing the coursework around seven-thirty.

Now a bit about the course itself. In my opinion, about one third of it is a review of stuff you are already supposed to know, namely how to dive hyperoxic mixes, or "Nitrox." Nitrox certification is a pre-requisite, but I presume that IANTD knows people have a habit of forgetting what they memorized just to earn their C-card, so they make you do it again. I personally didn't mind this one little bit, especially at this level.

Another third is gas planning. I don't know if most people know this before taking a course like Recreational Trimix, but it can't be a bad thing to go over tank factors and psig/min over and over again.

The third third is selecting a "best mix" given a target PO2 and END for a dive in the deep end of Recreational diving. Driving END with trimix is the new material, but they really want to confirm that you have the basics in place. Again, fine by me.

All in all, the course materials are very straightforward if you have no problems with the arithmetic behind diving Nitrox. If you have been diving a computer for a few years and have forgotten how to derive an EAD with simple arithmetic, then some of the material will be a welcome refresher.

Oliver was a relaxed presenter and had no trouble answering questions that went beyond the materials. I enjoyed sitting with him learning about diving, and I would repeat the experience. We had scheduled the two dives for Tuesday morning, so we went to his compressor station and analyzed my tanks after finishing the coursework. Oliver then sent me home with homework: Plan two dives on 32/20 to depths of 120' and 100' separated by a ninety minute surface interval. My cab was waiting, so back to my hotel where I was reminded that plans for sleep are expressions of optimism when you have a one year-old waiting for you

Next: We go diving

 

[jtivat]

I am curious as to why you chose to do this class in warm water? You are from Toronto so I assume most of your diving is cold yes?? If so why would you not train in the same conditions and gear you will do the real dives in? If you are planning on most of our dives in warm water then just ignore me.

 

[Reg Braithwaite]

Now to the diving. Oliver had us booked with Anita Divers, he doesn't operate his own boat. There was a bit of a kerfuffle getting hookd up with the dive boat due to some wether conditions that made it challenging for them to get to my hotel's dock, but everything finally got figured out. Once on board, I discovered there were several different groups aboard, each with their own DM or instructor. The boat was big and comfy, I liked it fine. We set off for our first dive, 120' off Palancar Bricks.

Oliver reviewed my plan, and we had a good discussion about how one deals with multi-level dives given just an air table. Although I had a computer as back-up, he insisted that we plan the dive manually and fly the dive manually, using the computer strictly for a mental bail-out. I had prepared a list of rock bottoms calculated for my tank at various depths and I also a similar list of "no deco limits" for various average depths in my back pocked based on a different system. Oliver was ok with my plan and we discussed our deco carefully. Although this wasn't a square profile dive, we planned a deep stop just in case we decided to ascend directly from depth. We also planned stops at 30', 20', and 15'. I am not endorsing our plans, just reporting what IANTD trains you to do.

Oliver also warned me that on the first dive after experiencing the effect of diving Trimix at depth, I would do a skill test at moderate depth, namely he would signal that I was out of air and I was to remove my regulator and swim 40' or more to him without air.

We were first off the boat and after doing a bubble check we descended the wall to 120'. I can't really say how clear it felt compared to air: My last dives to 120'+ feet have all been in cold, Ontario water. Maybe I was just enjoying the warmth of tropical diving. But it felt very easy, and after a few moments of swimming along the wall, I noticed Oliver had swum a fair distance from me. I was just kicking my frog kick up a notch to stay with him when boom, he gave me the signal. I was OOG!

I removed the long hose from my mouth and left it hanging around my neck, put both hands out in front of me like the free divers I have seen, and tried to make the most efficient frog I know how, with long, easy strokes and gliding as much as possible. I keep it up, and when I sneaked a look at him, he was swimming backwards away from me. Drat!

Eventually I started to struggle and he was right there. He put his long hose in my mouth, and when I signaled ok, told me to switch back onto my own reg. I don't know if he always planned to have me go OOG at 120' or if he thought I could handle it and changed the plan on the fly. But I will say that I felt calm and relaxed at the time. It was a bit of a surprise at first, but I was able to relax myself for the swim and try to maximize my efficiency. Would I have panicked if I had been diving air and been given the same test? Would I have gotten paranoid and tied up, struggling to swim quickly rather than smoothly? I can't really say for sure, but I can say that I feel a little more confident about diving that depth on that mix now that I've tried it.

And of course those of you who have dived Cozumel know what marvels I was enjoying on this dive. Wow. Everything felt amazing and wonderful. We enjoyed a leisurely dive, floating with the current up along the wall to the top and then over the coral formations at about 40'. The other groups from the same boat were below us, weaving through the swim-throughs as we floated overhead in the current, barely kicking at all. We eventually broke out the spools and lift bags then rose to do our stops at 30 and 20 feet. I broke with the plan and did my final stop at 10', I felt good about my buoyancy. I drifted as slowly as possible to the surface and we were done.

One down. One to go. During the surface interval I met three very nice divers from Washington State who were actually doing "Discover Scuba" dives with an instructor. Oliver dragged me back to reality and we reviewed the first dive and I planned the second dive, this one to 100'. The drill this time was a gas sharing ascent. I won't bore you with that, nothing as surprising as being OOG at 120'.

What was interesting was this. Oliver was diving what he called "half and half:" He had back gas and was slinging an AL80 with EAN38. On each multi-level dive he would breathe back gas until he rose above the EAN38's MOD and then switch. So the "stage" isn't really a deco gas and it isn't an extra bottle of back gas. I recall reading about some wreck divers who would do a similar thing as switching to a richer mix on the ascent would keep them out of deco.

Anyhoo, Oliver and I did another spectacular wall dive, and this time when we came over the wall he set off swimming determinedly. I set off after him. It was a long swim and after a while we left the reef behind us and were swimming across a sandy bottom, something like leaving a continent and sailing across the ocean. The water was very blue, and there was very little reference point, just Oliver hanging in the blue in front of me and this vast sandy bottom that could have been twenty feet or one hundred and twenty feet away.

I found myself glancing at my BT repeatedly for depth, sticking in the 37-40 range. I definitely was not pegged perfectly at 40', it was hard for me to lock onto my depth. I think it was an excellent exercise, it hi-lighted a skill that needs work.

After a long while another set of reefs appeared. By this time I was approaching my RB even for 40' and Oliver stopped. He unclipped his stage and clipped it onto me. I switched over to the richer mix and we set off again for another swim. This gave me a chance to get used to the feeling of slinging a bottle, and I knew I had back gas if I needed to switch out. It was fun. Eventually Oliver stopped and I handed the stage back to him, and we did our stops. This time I was tired, and my buoyancy was nowhere as precise as the first dive. We got back on the boat, and to my surprise the other divers surfaced very near us. I guess Oliver had arranged for us to be dropped off a ways from where the others were doing their second dive so that we could do another wall and have a swim. Looking back, the swim gave me a very good opportunity to focus on the mechanics of my finning, and I have some stuff to work on.

The boat returned to San Miguel and Oliver drove me back to my hotel in his truck, debriefing the dives as he drove. I did the exam later and managed to do a short review with Oliver the Friday night before flying back to Toronto on Saturday morning.

Overall, I enjoyed taking the course with Oliver and although I did a lot of reading and studying before sitting down with him, I definitely learned a lot from the entire experience. Thumbs up from me.

 

[Reg Braithwaite]

I am curious as to why you chose to do this class in warm water? You are from Toronto so I assume most of your diving is cold yes?? If so why would you not train in the same conditions and gear you will do the real dives in? If you are planning on most of our dives in warm water then just ignore me.

Good question. Consider training for a typical sport, let's say Soccer. You need to spend a certain amount of time training the "whole player" in game condition, scrimmaging, playing "friendlies" with other teams, and so on. And you also benefit from doing highly specific training where you try to work on one thing and eliminate other distractions. for example, you do wind sprints or lift weights or practice taking hundreds of penalty kicks.

I thought this was a very specific course that would be mostly the math. I am already used to diving a long hose, BP/W, and so on in gloves and dry suit, so I didn't think there would be a big win doing the course in Ontario. But I agree, if I were doing something with a greater emphasis on skills and buoyancy, I would want to do it in my dry suit and in my home waters. A wreck course, for example.

 

[Kevrumbo]

Wish I had Trimix on Maracaibo Deep and the Devil's Throat Dives . . .nice report!

How much is Helium there (per cuft or per liter)?

 

[Reg Braithwaite]

How much is Helium there (per cuft or per liter)?

Not sure. I believe Oliver does his own fills. He charged me an arm for the one tank and a leg for the other relative to Nitrox, but in his defense he gave me a complete quote of how much everything would cost before I booked with him, there were no surprises. I haven't shopped for Trimix in Cozumel, he might have given me a very good deal, I don't know.

Next time you are down there, you might want to talk to him and see what he has to say about diving Trimix and how much that would cost.

 

[Kevrumbo]

Well . . .it's nice to have that option/tool to use Trimix wherever you travel to, and if it's available. In Truk Lagoon for example, helium is $0.14 per liter, so for a 20/20 mix --you're looking at around a $80 fill for a single 11L tank.

 

[TSandM]

Reg, sounds like a pretty good class. There is nothing for building confidence and diving skills like being subjected to a little stress, and I suspect the OOA at 120 fsw was somewhat of a compliment, because I don't think an instructor would have done that if he had any worries about what he had seen of your diving that far.

Helium would have been nice in Coz, to do some of the trademark dives like Devil's Throat. We dove 32% and stayed at or above 100, so we missed them.

 

[rjack321]

Maybe I missed it...
what tank(s) were you diving?
what was your mix?

did you actually do up to 15mins deco? or were all the dives no deco dives?

 

[Reg Braithwaite]

Maybe I missed it...
what tank(s) were you diving?
what was your mix?

AL80s with 32/20. The second dive featured a switch to EAN38, then back to back gas for stops.

did you actually do up to 15mins deco? or were all the dives no deco dives?

We planned "no deco" dives and stayed within "no deco limits," then executed stops at 30', 20', and 10' anyways. Planned decompression normally refers to deco stops designed to handle dives outside of the "no decompression limits," not these stops. The terminology is confusing as practitioners and agencies transition from older models featuring a direct ascent to the surface to models requiring deep stops from 75% or 50% on all dives.

Agencies such as GUE and UTD would call these "minimal deco dives" and teach making such stops as part of their recreational level training. Using GUE's terms, I executed minimal deco dives, which is appropriate for this course.