Taking TDI Trimix

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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.


Hey Kosta,

I am getting trained on the stealth in about a month. I plan on doing tec with it once I get enough dives in to get everything adjusted and comfortable with the system. If I may ask, who was your instructor? Would you recommend them for advanced nitrox/deco? Thanks!
 
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).

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Not to nit pick, but isn't that a standards violation:

The TDI Trimix course provides the training required to competently and safely utilize breathing gases containing helium for dives that require staged decompression, utilizing nitrox and / or oxygen mixtures during decompression to a maximum depth of 60 metres / 200 feet. The objective of this course is to train divers in the benefits, hazards and proper procedures of utilizing custom oxygen / helium / nitrogen mixtures as breathing gases. Gas mixes are not to have any less than 18 percent oxygen (O2).
 
Not to nit pick, but isn't that a standards violation:

The TDI Trimix course provides the training required to competently and safely utilize breathing gases containing helium for dives that require staged decompression, utilizing nitrox and / or oxygen mixtures during decompression to a maximum depth of 60 metres / 200 feet. The objective of this course is to train divers in the benefits, hazards and proper procedures of utilizing custom oxygen / helium / nitrogen mixtures as breathing gases. Gas mixes are not to have any less than 18 percent oxygen (O2).

Technically, I suppose it is. I view it as possibly against the letter of the law, but totally within the spirit of the law. It's the difference between 17.4% and 17.5% on an analyzer. If it had analyzed at 16%, I would have asked for an O2 bump. But, for the small difference that it was (along with the reality of analyzer accuracy and the reality of the way helium seems to "mix" inside a cylinder), I don't view it as a problem. It's kind of like tech diving and deco in general. Measure with a micrometer, cut with an axe.
 
Hey Kosta,

I am getting trained on the stealth in about a month. I plan on doing tec with it once I get enough dives in to get everything adjusted and comfortable with the system. If I may ask, who was your instructor? Would you recommend them for advanced nitrox/deco? Thanks!
Yes, I’d recommend Don Pierce. Send me a pm some I can get you connected via email.
 
https://www.shearwater.com/products/perdix-ai/
http://cavediveflorida.com/Rum_House.htm

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