Is anyone diving the Hollis prism?

[stuartv]

@houdini0118 Congrats! I just started diving my rEvo at the end of December. I also did air dil and ART all together. Now, I don't ever want to dive OC again. LOL I can't wait to get ramped up more and then do the Normoxic Plus training, so I can work my way back to the depths I already did on OC.

Enjoy!

 

[kensuf]

Something I learned today:

IANTD and TDI use different terms for the same thing.

IANTD says "Normoxic Trimix" and TDI says "Trimix".
IANTD says "Trimix" and TDI says "Advanced Trimix".

IANTD says that if a diver is OC Trimix, they can do IANTD Normoxic Trimix CCR and IANTD Trimix CCR as one long course (presuming they meet the other prereqs, like 100 hours on the unit).

I had (mis)interpreted that to mean that my TDI Trimix cert would qualify me to do that. I have realized now that I was incorrect. I would need to have TDI Adv Trimix in order to qualify to do IANTD Normoxic and Trimix CCR as one combined course.

I could imagine confusion resulting if an instructor asks "do you have Trimix certification" and they mean IANTD Trimix, and the student says "yes" but they mean TDI Trimix.

Trimix used to be one program, the whole enchilada or nothing. In 1997 it was split into two courses, "Normoxic" and "Hypoxic" because there were people that didn't want to go to 300' but wanted the benefits of helium at 190'.

While I wouldn't expect the general diving population to understand the difference, I would hope any IANTD Trimix (Hypoxic) instructor would know that a TDI Trimix certification was normoxic and that any TDI Advanced Trimix (Hypoxic) instructor would know that an IANTD Trimix certification was hypoxic. Regardless, your certification card should also state your limitations of certification, so that should clear up any confusion at the end of the day.

I actually have a TDI "Trimix" (not advanced trimix) instructor card that was a full hypoxic trimix teaching cert kicking around somewhere...

 

[Jeremy Williams]

Tdi posted a set of equivalency tables but this is only the certs that TDI would recognize when meeting requirements for their standards. But it’s a good view I think...

TDI Equivalent Ratings with Other Scuba Diving Agencies - SDI | TDI | ERDI

 

[stuartv]

While I wouldn't expect the general diving population to understand the difference, I would hope any IANTD Trimix (Hypoxic) instructor would know that a TDI Trimix certification was normoxic and that any TDI Advanced Trimix (Hypoxic) instructor would know that an IANTD Trimix certification was hypoxic. Regardless, your certification card should also state your limitations of certification, so that should clear up any confusion at the end of the day.

My rEvo instructor that I have gone to (and expect to go back to) is awesome. I think so, anyway. But, I have definitely dealt with some other "tech instructors" (TDI and IANTD CCR instructors, no less) that I think might not live up to your hopes. They certainly seemed to not know the details of some of the other standards that I inquired about.

Maybe the industry should adopt some common terminology. No "Trimix" certifications. Only "Normoxic Trimix" and "Hypoxic Trimix" certs. No vagueness. No possibility of confusion. You know ... for the 5 people in the world who might have been confused for a few minutes otherwise...

 

[stuartv]

Tdi posted a set of equivalency tables but this is only the certs that TDI would recognize when meeting requirements for their standards. But it’s a good view I think...

TDI Equivalent Ratings with Other Scuba Diving Agencies - SDI | TDI | ERDI

Yeah... that table is somewhat useful. But, it has so many detail things that are wrong, out of date, or left out, that I would think it's really only useful as a rudimentary guide to tell you where to go look for better info. And not even great for that, since it appears that at least some of the links to other agency's info are broken.

I guess it's good for a TDI instructor, if they are verifying that a particular cert from another agency meets the prerequisite for a specific TDI cert. But, the relationship is not 2-way. E.g. IANTD ART satisfies a prereq to have TDI Helitrox. But, TDI Helitrox would not (in my opinion) satisfy an IANTD prereq for having ART.

 

[Jeremy Williams]

The entire standard for rebreather training at TDI is so out of date that even when it’s accurate it doesn’t make any sense to me.

Also, if I’m ranting a bit, the training materials from both TDI and IANTD are not very good for CCR. The CCR Diver online course from TDI spends an inordinate amount of time on SCR theory and operation. But the IANTD book reads like an academic journal where each “chapter” was really just a paper written in isolation by a different author.

 

[JohnnyC]

Interestingly enough, there are some certs you can get that allow freedom in one regard, but limit in another, so you end up with a cert from one agency that says OC 21%, END of 30m or less no deco, but another agency offers OC 55m air/nitrox only deco cert, but with unlimited deco gases. So you've got a diver certified to 55m on air, with unlimited choice of deco gases, but unable to use helium unless it's a 40m NDL dive with a limit of 30m END.

The joys of non-standard standards....

 

[Jeremy Williams]

I almost want to start an entire separate thread discussing why (WHY!!!) TDI Helitrox Dil CCR certifies you to do planned deco to 150ft but DOES NOT certify you to use the standard gas at that depth (i.e. 21/35) for bailout or dil. Insane.

 

[kensuf]

My rEvo instructor that I have gone to (and expect to go back to) is awesome. I think so, anyway. But, I have definitely dealt with some other "tech instructors" (TDI and IANTD CCR instructors, no less) that I think might not live up to your hopes. They certainly seemed to not know the details of some of the other standards that I inquired about.

Maybe the industry should adopt some common terminology. No "Trimix" certifications. Only "Normoxic Trimix" and "Hypoxic Trimix" certs. No vagueness. No possibility of confusion. You know ... for the 5 people in the world who might have been confused for a few minutes otherwise...

Here in North Florida, most of us use the phrases "Normoxic Trimix" and either "Hypoxic Trimix" or "Full Trimix" to differentiate the two programs. It gets real fun when you start talking Helitrox (which can mean two different sets of gases depending on the agency involved), Advanced Recreational Trimix, and TriOx. Or SSI's Extended Range (145', kind of similar to AN/DP) versus TDI's Extended Range (180' on air), "AN/DP" (TDI) versus Technical Diver (IANTD), etc.

 

[kensuf]

I almost want to start an entire separate thread discussing why (WHY!!!) TDI Helitrox Dil CCR certifies you to do planned deco to 150ft but DOES NOT certify you to use the standard gas at that depth (i.e. 21/35) for bailout or dil. Insane.

There's a standards change that I've been told is in the works which will allow this. Instructors wishing to use 21/35 DIL can request a waiver, I've done this, unfortunately the students will only be certified for 21/20 until the standards change happens.