Going From Tdi An/dp To Helitrox?

[stuartv]

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.

That is my plan. Dive as often as I can. Do deco dives as often as I can. Get more experience. Eventually get full trimix, when I feel like I'm ready. But, I would still like to have He as an option to use within my other current limits.

I have had NAS Part 1 training. Some of the diving I am likely to be doing is with my scuba group, doing underwater surveys of some different wrecks off NC. We did a preliminary site review of a wreck last weekend that we may be surveying this year. The depth is around 120'. That seems like a prime example of where it might be beneficial to me to be using He.


Anyway, I appreciate everyone's concern for my personal safety and/or need for more training. But, I would really like it if the discussion could focus more on the issues I have raised with the TDI standards and less on my personal circumstances.

Do you really think Adv Nitrox and Helitrox as standalone courses should have in-water requirements?

They don't provide any certification for the student to dive any deeper than the student was already certified for. They don't provide any certification for the student to do decompression diving, if they weren't already certified for that. They don't provide any certification for the student to use doubles or carry an extra cylinder that the student wasn't already certified for. So, why should those courses have in-water requirements? Doesn't Deco Procedures provide for all the in-water requirements and skills needed to actually take advantage of AN or Helitrox?

 

[KenGordon]

TDI have a problem with AN/DP. The two courses depend on each other such that they individually more or less useless, so I don't think you can use AN as a guide to principles.

As to adding Helitrox as a classroom only course. As an instructor would you want to sign someone off to dive helium never having been in the water with them? With no idea whether they can still do a proper ascent, hold stops etc?

The general view on helium (although now subject to review) is that it is less forgiving of deco mistakes and so a diver on helium needs to be a bit better than one on nitrogen for similar deco risk.

My expectation is that if you had Helitrox you'd not use it for those 120ft dives too often. The extra hassle and cost of the fills would be practical barriers. For example there are a couple of wreck I like to dive from Brighton, due to the tides they are often drived on consequitive days. I cannot get a helium fill for a twinset between getting off the boat one day and getting on it again in the morning.

 

[rjack321]

I think its BS that the instructor's first 10 students do the dives on air and students 11+ get heliox. Is the instructor qualified to teach the helium component or not?

 

[CptTightPants21]

I think its BS that the instructor's first 10 students do the dives on air and students 11+ get heliox. Is the instructor qualified to teach the helium component or not?

By that logic, we might as well allow an instructor to teach advanced trimix if he "is certified and actively dives to adv. trimix level".

There is always going to be different requirements for various instructor certifications from the different agencies. They are used as barriers to entry to help insure quality control, create agency loyalty, creates an instructor hierarchy, and provides a general check&balance. Some of these you might agree with, other you may not, but every agency needs a way to promote safety and a reason for instructors to move up the ladder. Otherwise you get situations where a guy who has had a cert for years, doesn't do a lot of a particular dive but still has the cert, is teach full cave courses and taking students to 250 ft.

Have just 10 tech student certifications is really a small and insignificant barrier, an active tech instructor has dozens if not hundreds of certifications to his name. It has already been covered in depth why heliox as a course isn't really that beneficial, but If you REALLY want heliox, find an instructor who has certified more than 10 students.

In my opinion, TDI's current standards are fine and I agree with the difference between taking the course with his current instructor vs a new instructor. Where Stuart gets off thinking he should get a tech cert from an instructor who has never seen him in the water before is beyond me.

 

[stuartv]

As to adding Helitrox as a classroom only course. As an instructor would you want to sign someone off to dive helium never having been in the water with them? With no idea whether they can still do a proper ascent, hold stops etc?

An instructor can sign off on Nitrox for an OW diver without seeing them dive and who may have zero dives since their original open water course (which could have been months or years prior - a friend of mine got his OW and AOW last Fall. He has 9 total dives and hasn't been in the water in over 6 months. He just got Nitrox certified, with no dives). Is an OW diver trying to stay at or above their MOD somehow inherently safer than someone with AN/DP certification who wants to add 20% Helium to their back gas?

The general view on helium (although now subject to review) is that it is less forgiving of deco mistakes and so a diver on helium needs to be a bit better than one on nitrogen for similar deco risk.

An AN/DP diver is certified to have adequate skills to dive in the ocean to 150', stay as long as they want/can, then hang at 20', on 100% Oxygen, for as long as they want/need. Are there people who really think that doing deco on Helium is more risky and less forgiving than doing a hang in the open ocean on 100% Oxygen?

There is someone or some group who thinks that I can have adequate skills to do unlimited deco on 100% Oxygen, but I need still better skills to be safe with 20% Helium in my back gas?

As a fresh AN/DP graduate, I personally feel MUCH better about doing a controlled, staged ascent from depth, than I feel about hovering at 20', breathing 100%. Don't get me wrong. I feel comfortable with using my judgment and doing both. I'm just saying that doing a staged ascent correctly and safely seems easier and less risky to me than a hover at 20' - particularly with the kind of conditions that I have seen some times in the open ocean.

My expectation is that if you had Helitrox you'd not use it for those 120ft dives too often. The extra hassle and cost of the fills would be practical barriers. For example there are a couple of wreck I like to dive from Brighton, due to the tides they are often drived on consequitive days. I cannot get a helium fill for a twinset between getting off the boat one day and getting on it again in the morning.

That kind of thing could pose a problem for me, as well. That's why I have two twinsets - so I don't have to get fills while I'm down for a weekend of diving somewhere. There is no extra hassle for me to get Helium. Both of the shops I frequent (and get my fills at) can provide trimix fills. The only extra anything is possibly an extra minute or two analyzing the tanks when I pick them up, and then, of course, the extra cost.

 

[stuartv]

By that logic, we might as well allow an instructor to teach advanced trimix if he "is certified and actively dives to adv. trimix level".

It doesn't seem so, to me. Helitrox does not certify the diver to dive any deeper or carry any more cylinders than they can with AN/DP. OTOH, a Trimix cert DOES cert the student to go deeper and use more deco gases.

And that really is the point here.

Certifying some number of students to dive to 150' and use one deco cylinder seems like a reasonable step to require before allowing an instructor to certify students to 180' and manage multiple deco cylinders.

But, how does certifying 10 students for AN/DP make any difference to an instructor's competence to teach an identical cert except for allowing 20% He in the back gas?

Have just 10 tech student certifications is really a small and insignificant barrier, an active tech instructor has dozens if not hundreds of certifications to his name. It has already been covered in depth why heliox as a course isn't really that beneficial, but If you REALLY want heliox, find an instructor who has certified more than 10 students.

Did you read my earlier posts? If so, you would already understand that the issue is the money and time required and why that much money and time seems unreasonable.

In my opinion, TDI's current standards are fine and I agree with the difference between taking the course with his current instructor vs a new instructor. Where Stuart gets off thinking he should get a tech cert from an instructor who has never seen him in the water before is beyond me.

So, every tech cert should require dives, regardless of whether that cert inherently requires any additional in-water skills beyond what the prerequisite certs require?

TDI holds to anyone outside TDI that I am now competent to dive to 150', perform staged decompression using one deco gas, and use 100% Oxygen for deco. But, TDI won't allow their own instructors to accept their own certification as sufficient evidence that I have the necessary in-water skills to use 20% Helium in my back gas for the same dives I'm already certified for?

The whole discussion seems to come down to the statement that diving with 20% Helium requires a higher level of skill in the water than what is required for AN/DP. I recognize my own inexperience and I am not saying that that statement is false. I'm asking if you all more experienced people agree with that statement. And what it is about about doing staged deco on Helium that makes it require more skill in the water than what is required to be considered safe to do deco on 100% Oxygen?

I have read Deco for Divers and Deeper Into Deco. I feel like I understood both of them about as well as you could expect someone to who took 2 years of Chemistry, Physics, and Thermodynamics 30 years ago. From my perspective, I am failing to understand what there is about a staged ascent with Helium that makes it require a higher level of in-water skill than doing deco on 100% Oxygen.

If there is no requirement for a higher level of skill in the water, then why should Helitrox certification be anything more than a classroom session for someone who already has AN/DP?

 

[CptTightPants21]

TDI already told you that the tech instructor who issued your card could issue you a helitrox card without in water skills. If you use a different instructor, you would at least need to get some in water time---their position is not only reasonable, but completely correct. Being rigid enough to ensure safety and liability protection, while still allowing a student to get the card as a minor "upgrade" should they want it from the instructor that has actually seen them dive.

Helitrox isnt' a popular cert exactly because it is so limiting. I've mostly seen people get it in with the Adv Nitrox/Deco package as a free add on and then use it for a dive or two to go a little deeper than 150. Just so we are clear, your tech instructor hasn't certified more than 10 students and that is why you can't get the cert?

You actually think that TDI card AN/Deco card means something to me. I (and many of us) have seen how little value that certification can have depending on the student/instructor. Any instructor that has never seen a student dive and issues a tech cert loses my respect. (and should rightfully be sued should anything go wrong)

And Nitrox is radically different than Adv Nitrox. They aren't even in the same galaxy. If you can't see that, I'm not sure what else there is to talk about.

 

[stuartv]

I don't know how many AN/DP certs my instructor has done. I know that he is working to get enough certs done to get his full Trimix instructor cert. I believe I mentioned that earlier.

My reading of the standards is that it looks like, to get a Helitrox instructor cert would be another class for him. So, I think he doesn't want to bother with getting a Helitrox instructor cert. I think he's holding out to go straight to getting Trimix instructor cert.

I understand the difference between Nitrox and Adv Nitrox. I think perhaps you are choosing to ignore the real point.

You can take Adv Nitrox as a standalone course, without taking Deco Procedures. But, that would then mean you are certified to use Oxygen - but not certified to do deco dives and not certified to dive with deco cylinders. I.e. it's pretty much useless without DP. Yet you can get it. But, since there is no actual use for it without DP, why require in-water skills? If you take DP, you're going to have to demonstrate the in-water skills. So, what is the point of also putting the in-water requirements in the AN course?

Similarly, once you are certified for DP, you have demonstrated the skills to do staged decompression. You haven't explained yet why Helitrox requires any more in-water skills than what you need for AN/DP. So, the question remains, if you have AN/DP, where does the need come from to demonstrate a higher level of skill?

Your response seems to be that some people are getting AN/DP that don't actually have the skills they should have. Okay. But, one, shouldn't that be addressed directly with DP course and instructor standards, rather than adding in-water requirements to other certs that shouldn't need them? And, two, if I had an AN/DP instructor that certed me when I shouldn't be, how does adding in-water requirements to Helitrox make anything any better? I can go right back to the same instructor for that, right? Possibly after waiting for them to cert 9 more people. How does that make me any safer?

In other words, if an instructor is a bad instructor, then does it really help to put the same in-water requirements from DP into the Helitrox requirements? If if they are a good instructor, then why does Helitrox need to have the in-water requirements?

If TDI changed the standards so that AN and Helitrox were classroom-only and DP was where the in-water requirements were, then why would it be a problem for any tech instructor to issue a Helitrox cert without seeing the person dive - just based on them having AN/DP plus passing the classroom course? Why would the instructor have any more legal or moral responsibility than an instructor that issues a Nitrox cert without seeing the person dive?

The instructor would not be certifying the diver to do anything new except add an additional gas to their mix. Just the same as an instructor issuing a SDI Computer Nitrox cert.

 

[CptTightPants21]

Please look at Advanced Nitrox standards
https://www.tdisdi.com/wp-content/uploads/files/sandp/currentYear/TDI/part 2/pdf/individual/TDI Diver Standards_07_Advanced_Nitrox_Diver.pdf

Advanced Nitrox requires in water dives and skills. Please find me an instructor that would teach Advanced Nitrox as a stand alone course.

I think there was a post on here once with some extenuating circumstances where a guy only took Advanced Nitrox as a stand alone class. The instructor gave him the same exact class/skills as his usual Adv Nitrox/Deco class. They are technically separate in TDI, but not really. Which is why 99% of AdvNitrox cert are issued with Deco. I am not even sure how an instructor could conduct an advanced nitrox class without covering the deco procedures material. Other agencies/instructors just have courses called Advanced Nitrox which covers all of Deco/Nitrox. Don't get too hung up on course names in scuba.



At this point, I am confused at what you are even asking? Is the below correct and/or can you restate in 1 to 2 sentences.

"I believe that helitrox should be a classroom only class, with a prerequisite of both AN/DP certifications"

If the above is correct, my answer is that no self respecting tech instructor would ever issue a tech certification with out seeing the student in the water.


Helitrox doesn't require any more in-water skills if you use the same instructor as AN/DP. It requires more in-water skills if you GO TO A DIFFERENT INSTRUCTOR. Your entire point is that you should just be given a certification blind by an instructor based on what some other instructor signed off on you. That's almost like saying if you passed GUE fundies, you should automatically be given SDI buoyancy, computer nitrox, and drysuit cards since those skills are required to pass fundies so why should the instructor need to see me in the water.

TDI has not changed standards so stop creating this random fantasy land. Advanced Nitrox and Helitrox will always have in water standards, because those are the actual cards that matter. You're never going to carry around and whip out your deco procedures card. You are going to carry around the advanced nitrox/helitrox card to get fills and as proof of certification.

I don't know all of TDI's procedures, but It sounds like your instructor is going for his trimix instructor cert--If it is his advanced trimix instructor cert then he can teach all of trimix, if it is only his basic trimix cert, then he can probably teach basic trimix and below (which would include Helitrox). At this point your instructor is not qualified to teach/certify to ANY degree of helium. Which makes sense.

 

[stuartv]

I have read the standards. I said that AN can be taught standalone. I did not say that it can be taught as classroom only. I have understood from reading what some places offer as courses that some people do teach a combo of Intro to Tech along with Advanced Nitrox, but not including DP.

But, if you take AN without DP, you're not actually certified to do deco dives, so what use is it? The only prereqs for AN are to be 18 (or 15 with parental consent), have TDI Nitrox (also requires no dives) and have 25 logged dives. It doesn't certify you to do deco or even carry a deco cylinder. As far as I can see, AN gives you nothing except allowing you to dive with a Nitrox blend higher than 40% as your back gas, if you wanted to for some reason. I.e. pretty useless. So, to get just AN, why have any more in-water skills requirements than you had to have for TDI Nitrox? I.e. none. When you do something that would allow you to actually make use of AN (i.e. take DP), THEN you will have to have the in-water skills.

Similarly, Helitrox doesn't let you do any more advanced or technical dives than you can already do with AN/DP. You're already able to do dives to 150' with deco on O2. The He would only make you safer, by being more clearheaded. Why make you demonstrate skills again that you already had to demonstrate to get your current certifications? That doesn't make any more sense than requiring in-water skills to get Computer Nitrox.

So, yes, after me saying it numerous times, you have got it. Why should Helitrox not be classroom-only with a prereq of AN/DP? Why would any instructor have any more problem with that than teaching Computer Nitrox with no dives, to an OW diver? Classroom-only Helitrox for an AN/DP diver seems less risky, to me, than classroom-only Nitrox for an OW diver.

And instead of trying to broaden the discussion to "any tech cert", can we please retain the original point of just talking about a cert to add 20% Helium with no additional depth and no additional deco gases to a diver who is already certified for 150' and 100% O2? Helitrox seems to be a special case as it's the only Tech cert that doesn't add any depth or cylinders. AN/DP takes you from 130' to 150' and adds a deco cylinder. Trimix takes you to 200' and adds a deco cylinder. Adv Trimix takes you to 330' and a travel gas. All those seem to have good reasons to require more advanced in-water skills. So, trying to expand the discussion to "any tech cert" is just obfuscation by straw man, I think. Helitrox is a special case, and I think it makes sense for the standards to treat it as such.

Finally, yes, I know that TDI has not changed it's standards. If you read my OP (1-3, actually), you will see that I stated right up front that the point of this thread was to talk about and possibly foster a change in the standards.

So, please tell me specifically why, in the specific case of someone who has AN/DP, they shouldn't be able to add 20% He to their mix by just getting the additional classroom training on Physiology and Planning that is appropriate?

So far, all I can get from your posts as reasons are:

- Because some people have AN/DP who shouldn't. And,

- Because no decent instructor would issue "any tech cert" without seeing the person dive.

If that's all there is to it, then why should any shop give me an Oxygen fill without someone there seeing me dive?

And, okay, decent instructors follow the standards. And the current standard is to see the person dive. But why shouldn't the standard for Helitrox change (to classroom-only, if the person has AN/DP)?

It seems to me that AN/DP either means nothing and shops shouldn't give me O2 fills without seeing me dive, because of the potential liability, or AN/DP means what it says it means and standards should allow me to use 20% Helium with only some additional classroom training.

I know you think I'm just being argumentative and pig-headed. But, I am really trying to understand what it is about using 20% Helium that makes it require a higher level of in-water skills than what is required for using 100% Oxygen. If it doesn't require any higher level of in-water skills, then requiring an AN/DP diver to, essentially, repeat the whole DP course just to add 20% Helium seems to be nothing more than a crutch to account for a feeling that some AN/DP divers really shouldn't have even been certified for AN/DP at all. In which case, the in-water requirements seem like a bassackwards way to try and deal with that.