Going From Tdi An/dp To Helitrox?

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Stuart, my first trimix qualification was BSAC SMG. It is a 50m qualification to use 20/30. Prior to that course I had was a BSAC Dive Leader which is a 50m nitrox qualification and ADP which is an accelerated deco (single stage) qualification. By your logic I should have been able to just turn up for an hour or two of theory and walk off with the qualification without getting wet.

If you accept the theory that helium is a 'fast' gas then the risk and consequences involved of cocking it up are greater than with nitrox. One minute of missed helium deco is worth more than one minute of nitrox deco. Thus all the risk are worse. To keep yourself safe you have to be less likely to cock up. The judge of that is the instructor handing over the cert.

I don't know how the standards compare for BSAC SMG and BSAC DL + ADP. But, it they are identical except for the classroom coverage of Physiology and Planning and the in-water skills required are the same, then yes, it does seem like you should have been able to get the SMG with only classroom. However, I doubt all the standards, including in-water, are identical, save for 2 chapters of the book, so the question is probably moot.

Or perhaps you are saying something different than the rest of the replies here. It seems like you're actually suggesting that the use of 20% Helium, down to 45m, DOES require a higher level of in-water skill. Is that it?


Another thing I thought to point out is that, as an example, the Oceanic family of computers that has the DSAT algorithm (e.g. Atom, Geo, etc.) is significantly less conservative than any tech diver I have seen. Tech divers generally seem to agree that diving with GF 99/99 would be crazy. But, I have compared the NDLs in the Atom 3.0 manual to what you get when doing a dive plan in Multi-Deco or planning on a Petrel. The Oceanic computers set to use DSAT and no Conservatism Factor produce NDLs that are VERY close to what you get when planning with Buhlmann (ZH-L16, but I can't remember now if I used B or C) and GF99/99.

So, in terms of the risk of getting bent, it seems like any ordinary Rec diver with an Oceanic computer is more likely to get bent than somebody who has full AN/DP training and then has a classroom session/exam and starts using 20% He on the same dives they're already doing.

So, seriously, how realistic are the concerns about getting bent from starting to use 20% He after AN/DP plus a classroom session for the He? Surely one would expect that a diver with AN/DP certs and even diving a liberal GF High of 85 would be less likely to get bent using 20% Helium than a Rec diver with 4 OW dives under their belt, diving a computer that is the equivalent of GF 99/99, using a big tank, and staying down right up to their NDL (as I was doing last Summer with only 30-something dives in my log - it's not that hard, even for a new diver)?

Or, as I have already asked to a resounding silence, what would be the actual argument to TDI to stop them if they announced a change to the standards to make Helitrox have prereqs of AN and DP and then Helitrox is classroom-only? What risks are there to be genuinely legitimately concerned about?

The increased risk of getting bent? And what is the real magnitude of that risk? Is it about like the chances of getting blown off a wreck and having to do a free ascent? Or is it more like the chances of losing all your deco gas, and losing your buddy, and getting lost and having to do a free ascent?

I'm being sincere. It seems like the increased risk of getting bent when diving to 45m and using 20% Helium would be dang near negligible compared to doing the same dive with the best mix of Nitrox. But, I realize I'm extremely inexperienced, so if that's wrong, someone please explain it to me. @KenGordon, you referred to the physiology of Helium and said that shorting yourself 1 minute on Helium is worse than 1 minute on Nitrox. But, the reading I've done on deco makes me think that the risk really is pretty dang near negligible - in terms of the increased likelihood that you'll get bent because of it. As in, if you get bent, you would likely have gotten bent anyway. If you weren't going to get bent anyway, then you probably won't get bent because you had 20% He instead of an extra 20% N2. And it might all be offset by the extra clear head making you less likely to screw up your ascent in the first place. The extra clear head saving you from mistakes on the bottom definitely seems likely to skew the overall stats for getting hurt in favor of being able to use the Helium.

@KenGordon, do you honestly think the decreased safety of Helium's less forgiving deco is a bigger downside than the increased safety of being more clear headed?
 
Ken's point is that helium is NOT nitrox and is not something that just given out regardless of whatever cards you can show an instructor. Every tech certification has a certain bit of "trust, but verify" mentality. Just because you have a certification from one instructor doesn't mean you you should be given a certification from another.

I know a guy who complete Padi tec 50, who wasn't happy with his instruction and is taking AN/DP with another instructor. Technically he already has AN/DP through PADI, but there is no guarantee he will pass this other instructors course. By your logic, he should just be given the AN/DP from the other instructor since he already passed all the requirements in PADI---technically PADI tec 50 has higher requirements and standards. And before you start with "Well, its a different agency...." If he had a TDI AN/DP and was not happy with it, the same exact situation would exist because your previous cert mean nothing when you are going to a new instructor. You want his name on your card, you prove it.

You say you are inexperienced, you are just trying to be sincere......all true and yet total crap. It doesn't matter what is said, you just ignore it and keep stating the same flawed ideas and then throwing in red herrings and rambling tangents on different topics like comparing GF and different algorithms. You have been given ample reasons by every one who posted in this thread (seriously not a single person has agreed with your viewpoint) about why a tech instructor (reputation, liability, etc) cannot and should not issue a blind tech certification without seeing a diver in the water.

If Helitrox is done in conjuntion with AN/DP--like it almost always is now, no issue. It has in water skills.
If your AN/DP instructor wants to give you a helitrox upgrade later on without doing skills--again that is ok, and the way standards are today.
If you plan on making Helitrox a stand alone course with no in water skills so that any random instructor can give out the certification to any AN/DP certified diver---NO. When are you going to understand that there this is no such thing as a no-dive card at this skills level?

This is the position of TDI, this is my position, and this is the position of every other poster up until this point. There hasn't been resounding silence as you put it, only you ignoring anything you don't like to hear. It's not learning if you refuse to listen to any voice that doesn't agree with you. You have less than 70 dives and over 1700 posts. I know we are on Scubaboard, but dive more, post less.
 
Stuart, you should have just waited until your instructor finished 10 other students at the AN/DP level, then you could have done the 20% helium upgrade easy breezy.

Wonder what happens to an AN/DP class of 3 where divers A and B are the 9th and 10th students certified. Diver C is the 11th and can get 20% helium while his classmates cannot...
 
Well.... I started the class last August. It took a long time because of all the students' schedules plus winter rolling in and nobody wanting to do big travel to continue training and do checkouts. So I didn't finish until last week. But, hey, I got a LOT of training in, in the pool and the local quarry. Anyway, when I started the class, Helium wasn't really even on my radar as I knew I'd want a lot more experience (than I had at the time) before even thinking about that. Now, I have 30-something more dives, plus many pool sessions, and Helium IS on my radar. Nothing urgent, but I'm a lot more interested in planning and working towards it than I was last summer.

As far as the the class that includes students 10 and 11, I don't know that it's really an issue. I THINK (just think, mind you), that the instructor would have to cert student number 10, then go take the instructor course to get Helitrox Instructor certified then come back and do certs for Helitrox. So, neither #10 or 11 would get it along with their AN/DP. But, they could both get it as soon as the instructor finished their Helitrox Instructor cert.
 
It seems to me, you put way more stock in your cert card than anybody else does, or ever will.
 
**** it. Safari ate my post. It was mostly about helium being fast and these courses assuming that is a proper issue.

Bottom line, do 60m trimix with a different instructor. Try to find the people near the top of the pyramid that teach the instructor trainers. Don't piss about with some amateur doing it for pocket money when retired.

Explain "I am only here because I was taken in by a wannabe instructor at 45m and I am jealous of my GUE mates who have to use trimix at 30m". (Everyone has been too polite so far, sorry)

You will LEARN a lot. Your normal 40m single stage stuff will become EASIER. Your CONFIDENCE will improve. Your ARROGANCE may be reduced, especially if you fail.

I am sorry if that sounds terribly condescending.
 
there is a difference between helium and nitrogen. helium goes in and out of solution considerably faster, so that will have an impact on your deco schedule making gas management more critical. Your buoyancy skills do need to be more precise when diving helium based mixes, ascent rates are important and being able to hold a deco stop. you also need the maturity to realize that helium is not a magic gas and may over-complicate a dive
 
I could understand if GUE or IANTD or someone else didn't accept a TDI certification as satisfactory evidence that the person has demonstrated a certain level of skill.
GUE instructors occasionally get students with tech passes who show up without the skills for a basic tech class. What happens then is not that the instructor says well, he's got the cert, let's go. No, I'm told that what happens is their fundamentals instructor gets a really unpleasant phone call and the student usually gets what amounts to a second, very expensive, fundamentals class and doesn't get a card.

Nobody competent trusts someone else's evaluation of a student. The instructor is putting his professional rep and his livelihood on the line with every single student they certify. Maybe the original instructor had a weak moment or maybe the student has managed to forget how to do something critical, or just hasn't dived for a year, etc. Anyone who would do this is not someone you want to take a class from.
 
It's been a while, but I figured I would post a follow-up here in case anyone like me comes along later and reads this thread.

IANTD offers a course called Open Circuit Recreational Trimix. That certifies a diver for recreational dives to 130' with up to 25% Helium. I have just gotten email confirmation back from IANTD that the course does not require any dives (though an individual instructor may, at their discretion). Prerequisites are to be at least 15 years old and have the Deep Diver specialty.

So, for someone in the position that I'm in that wants to be able to add some Helium to their mix, the IANTD OC Rec Trimix course may be an option to look into, instead of putting all the time and money in that is required for TDI Helitrox.

Just an FYI for posterity.
 

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