What goes into a Trimix course?

[LiteHedded]

PO2 doesnt cause vasoconstriction, FiO2 does, you're still on 100%. 10ft may not be a transitory depth if you are trying to get the PO2 down, many of us prefer a 10ft final stop depth and do at least half of our O2 stops up there, but either way, was just curious what you guys did for air breaks when the mixes were that rich with helium from both an ICD standpoint as well as a pO2 standpoint.

on the normoxic issue.
read up on the GUE S&P and while my bias here is for cave diving, I think they have it right aside from the time limits for decompression which is confusing to me. Take Cave 2 so you can do deco dives, then Tech 1 for narcosis management if you're going below 100ft, then Tech 2 which is equivalent to TDI advanced trimix and IANTD's trimix diver with a depth limit of 300ft with introduction of big helium mixes for depth advantages vs narcosis management and multiple bottle handling.

My point still stands, I don't agree or believe in "normoxic trimix", "tdi trimix diver" whatever you want to call it because I don't think the step is big enough to warrant a separation between what they call normoxic and the ART/helitrox course. I much prefer GUE's approach to it as a two step with the introduction of helium to what is essentially the an/dp class for open water.

If you don't trust your students to limit themselves to progressive penetration by experience, then why are you certifying them in the first place? With TDI's normoxic you've basically given them all of the skills, so why should they have to come back just so you can make sure they know how to use a travel gas and a second deco bottle? What is the justification? From reading the GUE S&P you guys are actually teaching meaningful and new skills in each of the courses, I don't see that from the other agencies, so no, I don't believe in normoxic trimix as a course.

I do have a couple genuine questions for you @PfcAJ . Litehedded said that 12/70 isn't taught in Tech 2, so what gas are you using to get to 250ft or was that not accurate? The other is the time limits for Tech 1 and Tech 2. How do those apply for cave diving assuming you have Cave 2 or Cave 3 certs where there isn't a minute limitation for decompression? I don't think I'd be able to do any cave dives at the Cave 3/Tech 1 level and limit the dive to 30 minutes of decompression, heck the Cave 2/Tech1 limits would be very difficult, and a 60 minute limit at Cave3/Tech 2 combined level would be essentially impossible.

15/55 is the tech 2 gas. in that class you'll do dives to 250ish with a stage and two deco gases.

i think every tech diver should take tech 2. I think it would be a very good class for you to take, for instance, but it's very expensive so people will take the class from other agencies 9 times out of 10

typically by the time someone is at the cave 2 tech 2 level they will set their own limits and dont worry too much about what the gue standards say. when you start doing extended range deep cave diving there isn't a class for it. there's no combination of cave2 tech2 that will teach you to do a 4 hour bottom time in a siphon for instance.

 

[CptTightPants21]

PO2 doesnt cause vasoconstriction, FiO2 does, you're still on 100%. 10ft may not be a transitory depth if you are trying to get the PO2 down, many of us prefer a 10ft final stop depth and do at least half of our O2 stops up there, but either way, was just curious what you guys did for air breaks when the mixes were that rich with helium from both an ICD standpoint as well as a pO2 standpoint.

on the normoxic issue.
read up on the GUE S&P and while my bias here is for cave diving, I think they have it right aside from the time limits for decompression which is confusing to me. Take Cave 2 so you can do deco dives, then Tech 1 for narcosis management if you're going below 100ft, then Tech 2 which is equivalent to TDI advanced trimix and IANTD's trimix diver with a depth limit of 300ft with introduction of big helium mixes for depth advantages vs narcosis management and multiple bottle handling.

My point still stands, I don't agree or believe in "normoxic trimix", "tdi trimix diver" whatever you want to call it because I don't think the step is big enough to warrant a separation between what they call normoxic and the ART/helitrox course. I much prefer GUE's approach to it as a two step with the introduction of helium to what is essentially the an/dp class for open water.

If you don't trust your students to limit themselves to progressive penetration by experience, then why are you certifying them in the first place? With TDI's normoxic you've basically given them all of the skills, so why should they have to come back just so you can make sure they know how to use a travel gas and a second deco bottle? What is the justification? From reading the GUE S&P you guys are actually teaching meaningful and new skills in each of the courses, I don't see that from the other agencies, so no, I don't believe in normoxic trimix as a course.

I do have a couple genuine questions for you @PfcAJ . Litehedded said that 12/70 isn't taught in Tech 2, so what gas are you using to get to 250ft or was that not accurate? The other is the time limits for Tech 1 and Tech 2. How do those apply for cave diving assuming you have Cave 2 or Cave 3 certs where there isn't a minute limitation for decompression? I don't think I'd be able to do any cave dives at the Cave 3/Tech 1 level and limit the dive to 30 minutes of decompression, heck the Cave 2/Tech1 limits would be very difficult, and a 60 minute limit at Cave3/Tech 2 combined level would be essentially impossible.

Taken from a recent fundies work book pdf.

Up to 250ft use 15/55
Up to 300ft use 12/65
Deeper than 300ft use Helitrox

Those deco limits are during the course, although once a a diver has the card they are free to plan their dives accordingly. Once you have the Tech 2 card you can basically do anything and I have never heard a tech 2 diver say he can't do a dive because he has to limit his deco to 60 min. Similar to the GUE JJ CCR card. Officially, the course is only for mod 1. But every GUE CCR diver is also tech 2, eventually they will start diving the rebreather with trimix and there isn't any other Mod 2/3 course at the moment.

 

[LiteHedded]

Taken from a recent fundies work book pdf.

Up to 250ft use 15/55
Up to 300ft use 12/65
Deeper than 300ft use Helitrox

Those deco limits are during the course, although once a a diver has the card they are free to plan their dives accordingly. Once you have the Tech 2 card you can basically do anything and I have never heard a tech 2 diver say he can't do a dive because he has to limit his deco to 60 min. Similar to the GUE JJ CCR card. Officially, the course is only for mod 1. But every GUE CCR diver is also tech 2, eventually they will start diving the rebreather with trimix and there isn't any other Mod 2/3 course at the moment.

the rb80 course is very much a hypoxic trimix course.

 

[CptTightPants21]

the rb80 course is very much a hypoxic trimix course.

but the JJ is Mod 1

 

[LiteHedded]

but the JJ is Mod 1

cool

 

[CAPTAIN SINBAD]

My point still stands, I don't agree or believe in "normoxic trimix", "tdi trimix diver" whatever you want to call it because I don't think the step is big enough to warrant a separation between what they call normoxic and the ART/helitrox course. I much prefer GUE's approach to it as a two step with the introduction of helium to what is essentially the an/dp class for open water.
.

I was talking to Steve Lewis (Doppler) and I wish he comes into this discussion sometime. What I understood from him was that initially the depth at which TDI wanted to bring in Helium was 150 feet and not earlier. That was when their "Normoxic" or Basic Trimix certification made sense for it would be the first introduction to Helium. In UK and other low vis areas instructors were eager to introduce Helium at a much shallower depth and that is why the option of doing ANDP with Helium was introduced in TDI ANDP course. The certification depth of that was still 150 feet but you are correct that it kills the next course they are trying to sell.I think the course breakdown made sense in the initial form in which it was conceived. By adding Helium component in their ANDP they have created an overlap which has compromized their Trimix course.

 

[stuartv]

I feel like the TDI progression makes sense.

AN+DP (optionally, including Helitrox) teaches you basic deco planning and diving, and the u/w skill of managing 1 deco cylinder, with a certification limit of 150'(45m).

The next step teaches you how to manage 2 deco cylinders, allows you unlimited Helium, and bumps the depth limit to 200' (60m).

The final step teaches you to manage more than 2 extra cylinders and bumps the depth limit into hypoxic territory.

Whether you get to start using Helium at the 45m level with 1 deco cylinder, or wait until you have 2 deco cylinders at a 60m depth limit doesn't make much difference, to me. The progression still makes sense (to me). I am certified to dive with 1 deco cylinder now. I am comfortable with that, but I feel like I need to get a reasonable amount of experience diving like that before I want to take on diving with 2 deco cylinders.

It is the amount of gear I have to manage that I think needs to ramp up gradually. Use of Helium is incidental and comes with diving deeper. But, adding Helium by itself doesn't change my task load.

When I take TDI Trimix, I will be expecting to learn how to manage 2 deco cylinders. That is really the only "skill" to learn in that course, as I understand it (when coming from AN/DP). I also expect some class time on how to plan contingencies when you have 2 deco gases versus my current training of planning for 1. Whether I already use Helium or it's included in that step up is kind of irrelevant - to me.

 

[PfcAJ]

PO2 doesnt cause vasoconstriction, FiO2 does, you're still on 100%. 10ft may not be a transitory depth if you are trying to get the PO2 down, many of us prefer a 10ft final stop depth and do at least half of our O2 stops up there, but either way, was just curious what you guys did for air breaks when the mixes were that rich with helium from both an ICD standpoint as well as a pO2 standpoint.

on the normoxic issue.
read up on the GUE S&P and while my bias here is for cave diving, I think they have it right aside from the time limits for decompression which is confusing to me. Take Cave 2 so you can do deco dives, then Tech 1 for narcosis management if you're going below 100ft, then Tech 2 which is equivalent to TDI advanced trimix and IANTD's trimix diver with a depth limit of 300ft with introduction of big helium mixes for depth advantages vs narcosis management and multiple bottle handling.

My point still stands, I don't agree or believe in "normoxic trimix", "tdi trimix diver" whatever you want to call it because I don't think the step is big enough to warrant a separation between what they call normoxic and the ART/helitrox course. I much prefer GUE's approach to it as a two step with the introduction of helium to what is essentially the an/dp class for open water.

If you don't trust your students to limit themselves to progressive penetration by experience, then why are you certifying them in the first place? With TDI's normoxic you've basically given them all of the skills, so why should they have to come back just so you can make sure they know how to use a travel gas and a second deco bottle? What is the justification? From reading the GUE S&P you guys are actually teaching meaningful and new skills in each of the courses, I don't see that from the other agencies, so no, I don't believe in normoxic trimix as a course.

I do have a couple genuine questions for you @PfcAJ . Litehedded said that 12/70 isn't taught in Tech 2, so what gas are you using to get to 250ft or was that not accurate? The other is the time limits for Tech 1 and Tech 2. How do those apply for cave diving assuming you have Cave 2 or Cave 3 certs where there isn't a minute limitation for decompression? I don't think I'd be able to do any cave dives at the Cave 3/Tech 1 level and limit the dive to 30 minutes of decompression, heck the Cave 2/Tech1 limits would be very difficult, and a 60 minute limit at Cave3/Tech 2 combined level would be essentially impossible.

I'm going to have to disagree with you on the notion that ppo2 doesn't influence vasoconstriction. I certainly believe that gas breaks assist with deco efficiency, but I don't see any value in doing them shallower than 20'.

For a 250' thing I'd use 15/55 (maybe ramp up the helium some cuz I like it).

For what "cert" I'm using for dives, there isn't a really card for this type of stuff. You're given the tools, its up to you to apply the tools. Imo the best way to learn to do advanced dives is through mentorship on a long term project.

Fwiw, Cave 3 has a tech 2 prerequisite but no one takes C3 anyways.

 

[LiteHedded]

I'm going to have to disagree with you on the notion that ppo2 doesn't influence vasoconstriction. I certainly believe that gas breaks assist with deco efficiency, but I don't see any value in doing them shallower than 20'.

For a 250' thing I'd use 15/55 (maybe ramp up the helium some cuz I like it).

For what "cert" I'm using for dives, there isn't a really card for this type of stuff. You're given the tools, its up to you to apply the tools. Imo the best way to learn to do advanced dives is through mentorship on a long term project.

Fwiw, Cave 3 has a tech 2 prerequisite but no one takes C3 anyways.

i'm sure someone would love to sell a cave 3 or tech 3 class if they could find some takers

 

[CptTightPants21]

i'm sure someone would love to sell a cave 3 or tech 3 class if they could find some takers

My understanding is that Cave 3 and Tech 3 aren't really classes, they are more like learning "expedition" programs and have a longer duration.