Going From Tdi An/dp To Helitrox?

[stuartv]

I have just completed TDI Advanced Nitrox and Decompression Procedures as a combined course.

My instructor is an Adv Trimix diver, but currently his highest level of instructor certification is for teaching AN/DP. He told me that, were he certified to teach Trimix, he could have included Helitrox certification as part of the course I just finished.

I looked at the standards for DP and Helitrox and it appears that the in-water part of the standards is the same between the two. The Helitrox standards do not specify a requirement to actually use He as part of any gas mix on any of the required dives.

Thus, it seems like my AN and DP cards would be sufficient to document that I have already met the in-water requirements for Helitrox.

My question is: Now that I have AN and DP certification (well, as soon as my instructor enters them into your computer), can I find a Helitrox instructor and get the Helitrox cert by just taking a classroom-only course to cover the additional material for adding Helium?

I would like to be able to incorporate 20% He into my diving when appropriate, but it doesn't make sense if I have to pay a large fee for another whole course that is identical to the one I just completed, save for some additional classroom material. If that is the case, I will wait and pursue full Trimix certification sometime down the road.

A different way of asking my question would be: If I ask a Helitrox instructor to certify me for Helitrox without teaching a whole course, and without any dives, they may well respond that the standards for Helitrox require them to require me to do the dives as well as the full classroom curriculum. In that case, is there some statement from TDI that I can relay to them that would facilitate them being able to give me a classroom-only course to get my Helitrox cert? Are they allowed to accept my AN/DP cards as documentation of meeting the in-water standards? Can they call TDI to get a waiver for requiring me to do dives with them, so they can do classroom-only?

Thanks for any info/help!

 

[stuartv]

I could be missing something, but comparing the standards for DP and Helitrox, it looks like the only differences are the classroom portions, "3. Physiology", and "7. Dive Planning".

I would be happy to pay someone a reasonable fee to give me a classroom session on those two chapters of the course, in order to be able to use up to 20% He in my bottom gas.

 

[stuartv]

I emailed TDI directly and got a response on this.

- If my AN/DP instructor is certified to teach Helitrox, he could issue me a Helitrox cert without making me do more dives. But, if I go to a NEW (to me) instructor, I would have to do the full Helitrox course, which is effectively a repeat of the DP course.

- For an instructor to be certified to teach Helitrox, they have to already be an AN/DP instructor and have already certified 10 AN/DP students.

This has lead me to having several thoughts. I'm posting them here hoping to foster a productive discussion that might ultimately yield a change in TDI standards to make it easier for someone in my position to get the Helitrox certification.

My "position" is that I have gotten AN/DP certification, but my instructor, while an Adv Trimix diver, is not certified to teach Helitrox or anything higher. So, the only way I can currently get Helitrox certification is to spend the time and the money to, for practical purposes, repeat the DP course with another instructor.

Since Helitrox certification affords me no increase in depth or number of deco cylinders or anything else. It only allows me to add up to 20% Helium to the gas I'm using, repeating the time and expense of the DP course does not make sense, to/for me. But, the potential for additional safety on the dives I'm already certified for makes me want to be allowed to use Helitrox when I feel it is appropriate.

My thoughts are:

- Nitrox certification as a standalone course did not require any dives. I don't understand why Advanced Nitrox and Helitrox, if taken as standalone courses, would require any dives either. Adv Nitrox is, apparently, typically taken in conjunction with either Intro to Tech or Deco Procedures. Both of those have in-water requirements, which makes sense. If AN is taken at the same time, the student will have to meet in-water requirements. But, if AN (or Helitrox) is taken standalone, why do they need to require dives? Especially if at least Intro is a prerequisite for taking AN? And, really, why not make DP be required either as a prereq or be taken in conjunction with AN? What is the real use for AN if you only have Intro to Tech under your belt? Without DP, you're only certified for NDL dives, so what is the use for having AN at that point?

- The current TDI standards provide a significant incentive for an AN/DP instructor to accept a student that maybe really is not ready to start such a course, and to certify a student whose skills might be right on the edge of what is acceptable. At least, the incentive is there up until the instructor has certified enough students to meet the TDI quota.

- If an instructor has been certified as competent to teach AN/DP, and they are an active and experienced Trimix diver, why does certifying 10 AN/DP students have any bearing on whether that instructor is competent to teach Helitrox? Just like I feel like I ought to be able to get Helitrox certification, from AN/DP, relatively easily, it seems like an AN/DP instructor with sufficient Trimix diving experience ought to be able to get Helitrox Instructor certification relatively easily, too - meaning without a quota of AN/DP student certifications.

- I am now certified to dive to 45m, with one deco cylinder containing up to 100% O2, and any blend of Nitrox for back gas. All my research tells me that diving to 45m would be safer if I properly incorporated up to 20% Helium into those dives. Thus, I feel like the way TDI standards are currently structured, I have an unreasonable financial (and time) barrier to using a safer back gas blend for the diving I'm already certified to do. I am already certified to do any dive that Helitrox would allow me to do. But, being able to use Helitrox would make me safer. And I can't (without anteing up another, unreasonably large, chunk of money and time) because of current TDI standards.

- If using Helitrox on deco dives to 45m really does make me safer, then it seems like any TDI AN/DP instructor who truly puts the best interest of their students foremost would actually explain all that to any prospective student and steer them towards an instructor who could give them a Helitrox cert along with their AN/DP certs. Of course, that would make it really hard for any TDI instructor to ever advance past being an AN/DP instructor, since steering all their student prospects away would prevent them from ever making their quota..... And this comment is, in NO WAY, a cut at my AN/DP instructor. He did talk to me up front about Helitrox and I made my decision to train with him anyway. My thought is really to highlight what seems like another drawback to the current TDI standards.


Like I said, I'm posting this to try and foster a discussion. Really, I hope for one of two things. Either, I hope someone will explain to me why the status quo makes sense and it would be bad for the students and potential students to change things. Or, I hope TDI will change things so I can get a Helitrox cert for a further investment that makes sense, they will take away the incentives for instructors to certify students that are right on that Pass/Fail line, and they will set a more easily attainable bar for AN/DP instructors to be able to teach Helitrox.

 

[rongoodman]

At this point, why bother worrying about Helitrox? Just move on to normoxic trimix.

 

[stuartv]

Honestly, I don't feel my skill and experience are to the point yet where I am ready for full normoxic trimix. I just did my check out dives for AN/DP, so I have no REAL experience with deco diving yet. I feel like it's too soon for me to do the Trimix cert.

But, it seems to me that Helitrox would make the diving I am already certified for safer. That is my reason for being interested in getting that certification.

 

[elgoog]

Is there a time limit after AN/DP within which you need to do the Helitrox with your instructor to avoid doing the full course? You could wait until your instructor has certified enough AN/DP candidates and then do the Helitrox specific portion with him.
In theory, this would be some amount of time that allows you to get more experienced at your current limits (or shallower but with "real" deco) diving EANx but before you feel ready for the Trimix cert.

 

[KenGordon]

Honestly, I don't feel my skill and experience are to the point yet where I am ready for full normoxic trimix. I just did my check out dives for AN/DP, so I have no REAL experience with deco diving yet. I feel like it's too soon for me to do the Trimix cert.

But, it seems to me that Helitrox would make the diving I am already certified for safer. That is my reason for being interested in getting that certification.

Do normoxic, really it is just a course with an extra cylinder. You do not HAVE to dive to the limits if not comfortable. I suggest doing some shallower deco dives in the meantime where being narced isn't going to be the problem. Then you will be used to the extra gear, the knowing you cannot surface and other deco related stuff.

Or you could go to Mexico and do BSAC Sports Mixed Gas in two days, 50m up to 20/30 mix.

I am not entirely convinced by 25/20. The only dive I ever did on it was on AN/DP and it might as well have been air considering everyone's performance. Since then I have mostly used 18/35 for anything where narcosis might be an issue.

 

[Jim Lapenta]

I did Helitrox before I did AN/DP through NAUI. I could in theory go for Helitrox Instructor through TDI but in all honesty for me in my area the demand is not there to justify the upgrade cost since I don't have full trimix and I have had exactly one person ask me about the helitrox cert. I haven't used helitrox in a few years.

There are some things about using helium in the mix that I would want the dives. Helium is also expensive as hell. I like a little He below 100 but not enough now to spend 85-90 bucks for a fill for a 130 ft dive. 160 ft yes but those are few and far between for me lately.

He might make your diving safer in terms of less narcosis. What will really make it safer is to do a butt load of deco dives in the 100 -120 ft range and practice what you know. Then go for full trimix. AN/DP is not just about going deep where He is more beneficial. I can do a 35 minute dive now at 90-110 to explore a wreck and don't need the He to be safer.

Just as an FYI I had around 300 dives in before doing Helitrox. I got my AN/DP instructor card at about 600 dives.

 

[SeaCobra]

After reading your posts I feel you would benefit greatly from the full helitrox course.

 

[stuartv]

Is there a time limit after AN/DP within which you need to do the Helitrox with your instructor to avoid doing the full course? You could wait until your instructor has certified enough AN/DP candidates and then do the Helitrox specific portion with him.
In theory, this would be some amount of time that allows you to get more experienced at your current limits (or shallower but with "real" deco) diving EANx but before you feel ready for the Trimix cert.

I don't know that there is any hard limit. It would just be my instructor's judgment. But, we are both part of the same scuba "club" if you will, so I expect to be diving with him at least occasionally, outside of any class. So, he'll have a pretty good idea of how much I've been diving and whether I've been getting stale and need to do a full course.

So, yes, my current plan in effect is just wait for him to get the instructor cert and then get Helitrox.

My post was really to bring out the issue that I think the current TDI standards would make more sense if the Adv Nitrox and Helitrox certs as standalone courses did not have an in-water component.