Taking TDI Trimix

[wetb4igetinthewater]

When i did CCR Mixed Gas, which is the same course, the other student was OC and doing your course. He was unable to complete it as when we got to ‘tomorrow we are are doing 50m’ it was clearly not going to be safe. His problem was not about the skills taught on the course so much as more basic skills taught on ANDP and before.

So if you want to be doing skills ahead of time I suggest:

DSMB deployment.
Shutdowns (maybe not so hard in your configuration).
Taking off and recovering stages.
Passing stages back and forth.

In my opinion the main way to be prepared is to have done plenty of diving at the previous level. So, for you, lots of reasonably straightforward single deco gas dives of an hour or so in proper real world conditions.

If you are using side mount as shutdowns on a twinset are too hard I would also suggest getting into a twinset and doing shutdowns while neutral. Then everything else will seem easy .

Ken,

Excellent suggestions as I am now working on prepping myself for the class, diving at least once a week, getting settled. I'll bring the deco bottles that I will use for the class. I won't actually breath off them, just pressurize them, and take them on and off repeatedly. I'm big on DSMB deployment, as I teach it in OW and include it in every con ed course I teach.

Honestly, I may never dive twinsets again. I know, never say never, but I'd really. I have a roadmap for my training/progress in sidemount, from advanced wreck with Andy Davis to advanced technical sidemount with Tomasz Michura (i.e., lots of bottles, target is 6).

 

[RainPilot]

Hey Kosta. If you can check the switch protocols you will need to use, then taking “deco” stages of backgas and doing the actual switches will be pretty useful.

I don’t like taking gases I can’t use on a dive because Murphy is my dive buddy. I sometimes dive with 2 AL40 stages of backgas and mark one as 100 and one as 50.

Note, the labelling and analysis is done correctly, I just put a different mark on to show what they are simulating.

 

[rjack321]

advanced technical sidemount with Tomasz Michura (i.e., lots of bottles, target is 6).

I have to ask why you have a bottle target? And 6 is highly unrealistic in Puget Sound. You might need 5 on the SS Governor or the Bunker Hill (2x backgas, 1 stage of backgas, 2 deco gases). But honestly you'd be making a huge mistake doing those in sidemount in the first place. You might be the first to do them in the configuration though. Assuming you find someone to take you there, someone willing to split the boat and buddy with you, and that somehow you get proficient enough to actually get onto them. You would be better off doing them as 3 bottle CCR dives. I've been to the Governor 3 times, and go on it once. And I have 6 years of SM experience and almost 4 yrs on CCR. 6 bottle SM dives are not something you should be contemplating in Puget Sound (or Lake Washington but for different reasons).

 

[wetb4igetinthewater]

@rjack321,

I’ll never dive with 6 bottles, I just want the skill set to be proficient with them. The max I am going to do on OC is 2 bottles with 18/45 with deco bottles of EAN50 and O2.

For anything deeper than 200 feet, I’ll go CCR as the cost of trimix will catch up fairly quick. I’m not like the two Jeffs who every weekend are below 300 feet. That will never be me. At this point with my diving, I have difficulty justifying CCR.

I may or may not take an advanced trimix course on OC just for the training. We will see.

But I do know that I want to become extremely proficient in sidemount. You are aware of the extremely poor self-certified sm instructors that are around here. But that is another topic. Right now I want to become a proficient trimix sidemount diver.

 

[wetb4igetinthewater]

Oh, and just to get back to the OP, I was looking for what should be in the TDI trimix course that people think should be added. Good tips on preparation though! Thanks for that.

 

[stuartv]

Hey Kosta,

I'll be looking forward to reading your report(s) during and after your course.

I just finished TDI Trimix (and Extended Range) last week.

It was my first time attempting to use 2 deco cylinders during a dive. I did my course in backmount doubles, with an AL80 and an AL40 for deco bottles.

The toughest thing for me was cleanly and quickly stowing the 2nd stage and hose after switching off a bottle. I was carrying both bottles on my left. My instructor pointed out that the way I had my deco regs (Dive Rite XT1/2) setup, it would probably make stowing the hose easier if I flipped the 1st stage on the outboard deco cylinder, so that the hose on that one came down the outside of the tank, instead of the inside. That probably does not apply directly to you, in sidemount. The main point is that carrying and donning/doffing the cylinders was not the biggest challenge (for me, anyway). It was the actual use of them.

Good luck with the class! I'm sure you will ace it.

 

[wetb4igetinthewater]

Hey Kosta,

I'll be looking forward to reading your report(s) during and after your course.

I just finished TDI Trimix (and Extended Range) last week.

It was my first time attempting to use 2 deco cylinders during a dive. I did my course in backmount doubles, with an AL80 and an AL40 for deco bottles.

The toughest thing for me was cleanly and quickly stowing the 2nd stage and hose after switching off a bottle. I was carrying both bottles on my left. My instructor pointed out that the way I had my deco regs (Dive Rite XT1/2) setup, it would probably make stowing the hose easier if I flipped the 1st stage on the outboard deco cylinder, so that the hose on that one came down the outside of the tank, instead of the inside. That probably does not apply directly to you, in sidemount. The main point is that carrying and donning/doffing the cylinders was not the biggest challenge (for me, anyway). It was the actual use of them.

Good luck with the class! I'm sure you will ace it.

Stuart,

It was a great class, a bit of remedial sidemount training, but fortunately my instructor also dives an Xdeep Stealth Tec (and cave trained by Steve Martin), so my bottle handling skills improved ten fold. To start things off, we added stage bottle removal and replacement (not drops) just to address any lack of skill with diving with 2 stage bottles in sidemount (if anyone says I should have figured that out prior, I won't disagree, but sometimes you run out of time. Fortunately my instructor took the extra time to address that). We added other things like broken mask and replacement, which on first attempt made me attach a small ring to the top zipper of the butt pouch as it took me forever to find it without it. Mind you, I'm in dry gloves. I now have my backup mask and backup light in pouch that's accessible from the top zipper with a small ring so I can do it by feel faster.

People told me the difference in narcosis on the first day of dives would be monumental. It was. The next day was a little more challenging due to current. When swimming on the surface, we were being pushed out, so when we dropped, we went hand over hand until we dropped over the ledge. First dive on 21/35 to 175 we had the largest dogfish that I've ever seen. Normally those things take off when I shine a light on them, but this one was circling us for a bit. Due to the current though, we didn't stay down too long due to increased gas consumption rate. So we slowly ascended at an angle (had to counter the current and we slightly overcompensated, but just drifted back where we started).

I will say, sharing air ascents without a mask are not fun in cold water. But you've got to be able to do it obviously, though if that ever happened, I'd quickly switch masks after getting a reg.

With everything, it was a great class. I learned a lot, I was challenged, and I improved. The only thing I didn't like was the gas bill! I don't think I'll be doing a lot of trimix diving, but just occasional just to keep the skills fresh. When it comes to advanced trimix, I'l study that material academically, but I won't go below 60m/200ft on OC. That for me is closed circuit depths. Sure it can be done, but I'm not rich. But I'd like to learn more about how isobaric counter diffusion is addressed below 80 meters.

 

[EireDiver606]

Eye contact eye contact eye contact especially when doing drills and ascent/descent.

 

[stuartv]

Stuart,

It was a great class, a bit of remedial sidemount training, but fortunately my instructor also dives an Xdeep Stealth Tec (and cave trained by Steve Martin), so my bottle handling skills improved ten fold. To start things off, we added stage bottle removal and replacement (not drops) just to address any lack of skill with diving with 2 stage bottles in sidemount (if anyone says I should have figured that out prior, I won't disagree, but sometimes you run out of time. Fortunately my instructor took the extra time to address that). We added other things like broken mask and replacement, which on first attempt made me attach a small ring to the top zipper of the butt pouch as it took me forever to find it without it. Mind you, I'm in dry gloves. I now have my backup mask and backup light in pouch that's accessible from the top zipper with a small ring so I can do it by feel faster.

People told me the difference in narcosis on the first day of dives would be monumental. It was. The next day was a little more challenging due to current. When swimming on the surface, we were being pushed out, so when we dropped, we went hand over hand until we dropped over the ledge. First dive on 21/35 to 175 we had the largest dogfish that I've ever seen. Normally those things take off when I shine a light on them, but this one was circling us for a bit. Due to the current though, we didn't stay down too long due to increased gas consumption rate. So we slowly ascended at an angle (had to counter the current and we slightly overcompensated, but just drifted back where we started).

I will say, sharing air ascents without a mask are not fun in cold water. But you've got to be able to do it obviously, though if that ever happened, I'd quickly switch masks after getting a reg.

With everything, it was a great class. I learned a lot, I was challenged, and I improved. The only thing I didn't like was the gas bill! I don't think I'll be doing a lot of trimix diving, but just occasional just to keep the skills fresh. When it comes to advanced trimix, I'l study that material academically, but I won't go below 60m/200ft on OC. That for me is closed circuit depths. Sure it can be done, but I'm not rich. But I'd like to learn more about how isobaric counter diffusion is addressed below 80 meters.

LOL. I didn't have an issue with my gas bill. We dived air on all but my last dive (to 200'). We hit 180' on air, and I got my Extended Range cert, too. I didn't notice any real difference between 180 on air and 200 on 17/40 (we aimed for 18/45, but the final analysis before diving came out 17/40 - not enough difference to bin a dive). My instructor had me do a couple of things at 180 on air, to illustrate what narcosis does, but neither he nor I could recognize any significant impairment of my response times or cognition. I'm sure there was some, but I was happy it wasn't enough to really show.

Anyway, congrats on getting through and all the stuff you learned and refined! Sounds like it was a great class.

 

[rjack321]

But I'd like to learn more about how isobaric counter diffusion is addressed below 80 meters.

It's not addressed because in modern recreational deco diving it doesnt actually exist.

The plan is don't switch from trimix to deep air, problem solved.