TDI Deco Procedures.

[SailNaked]

I am considering taking TDI Deco procedures by itself. I do not intend to dive deeper than 150 at the moment however I would like to be able to use my doubles in some of the shallow wrecks near me. (Oriskany, Texas Clipper). I understand that adv nitrox is usually part of the package however my question is, if I am fine with decoing on 36-40% what would I be missing if I only took the one course?

[UCFKnightDiver]

Why wouldnt you want accelerated o2 deco? I suppose you could deco out on 36% or w/e, but it would just be a needlessly longer dive.

[ucfdiver]

Deco'ing on 40% is nickel rocketing at it's finest. Are you really willing to more than double the amount of deco time you have to save a few bucks?

[Michael_Lambert]

As said you are pretty much going to lose out on the opportunity to deco out on higher percentage of O2.

[rjack321]

I am considering taking TDI Deco procedures by itself. I do not intend to dive deeper than 150 at the moment however I would like to be able to use my doubles in some of the shallow wrecks near me. (Oriskany, Texas Clipper). I understand that adv nitrox is usually part of the package however my question is, if I am fine with decoing on 36-40% what would I be missing if I only took the one course?

You are missing helium.
You are missing any real gas gradient (Air on the bottom up to 36EAN for deco is lousy).
You are missing actually understanding enough about technical diving to chose the best options/plan for a given set of circumstances.
Might be hard to find like minded buddies willing to restrict themselves to your (limited and maybe not so prudent) dive choices.

[Michael_Lambert]

Helium?? In the advanced Nitrox course?

[rjack321]

Helium?? In the advanced Nitrox course?

Ummm yeah why not actually get useful training on something like 25/25 or 21/35 with O2 or EAN50 for deco depending on the dive.

Adv. nitrox alone doesn't even get the ability to switch gases, nevermind the lame 21% to 36% balony.

[Michael_Lambert]

Ummm yeah why not actually get useful training on something like 25/25 or 21/35 with O2 or EAN50 for deco depending on the dive.

Adv. nitrox alone doesn't even get the ability to switch gases, nevermind the lame 21% to 36% balony.

Don't get me wrong i am all about the Best mix for the dive; be it bottom gas or deco gas.

However the OP was saying they have no issues doing deco on upto 40% and wanted to know if there was any other benefit to the Adv Nitrox course which there really is not.

Now if they where going to be going down the road more and doing Long range dives or have the need to get into a Entry level trimix then sure the adv nitrox is needed for it.

[rjack321]

My only point was...
There are vastly better ways to dive to 110-150 than on air and <40% for deco. The only reason the OP "doesn't have a problem" with such a plan is because he doesn't have any training yet and doesn't (by his own questions) know what he's missing.

My answer is that deco proceedures by itself probebly shouldn't even be taught (by a reputable instructor) and that even adding Adv. Nitrox to deco proceedures is still missing alot.

I would find an instructor for NAUI, GUE or UTD course that gets you entry level helium, 50%, or 02 and then you have a whole lot more information and tools to make rationale dive plans with.

[Michael_Lambert]

I am not one to argue the Deep air debate.. being a student of GUE myself.. However i do feel their is some benefit to the two courses taken together, while planing dives within Recreational depths.

[SailNaked]

hmmm to piss off the Scuba cops or not to piss off the scuba cops?

Let assume I am only going to 130ft, and I plan to stay for 30 min and at most I will carry 2 deco bottles and I have 28% in my double 80s (cause that is what i have).

No class and I have a 59 min dive. (unless I use 100% @ 20ft then it is 49min.)

with Adv Nitrox I can use 50% and 100% and have a 48 min dive.

If the course is not meant to be taught by itself why is it? seriously for 11 less minutes in the water enjoying the fish?

Not trying to wad all yalls panties, just asking if the Deco procedures class is stand alone or if it is really useless without the Adv Nitrox.

I hear yall about Trimix, later I will go down that path, for now, just looking to have a reasonable bottom time on two local wrecks that happen to be at 130 ft.

[wedivebc]

Deco'ing on 40% is nickel rocketing at it's finest. Are you really willing to more than double the amount of deco time you have to save a few bucks?

What deco algorithm is giving you those results?

[wedivebc]

Not trying to wad all yalls panties, just asking if the Deco procedures class is stand alone or if it is really useless without the Adv Nitrox.

Yes the deco proc is pretty much useless without adv nitrox.

As far as the helium question is concerned there are a number of folks on here who are overly sensitive to nitrogen narcosis and will have you on He for anything deeper than a snorkel dive but for myself 130ft dive using 30% nitrox and a 50% deco mix is a good days diving.

[ucfdiver]

What deco algorithm is giving you those results?
Assuming back gas for the dive and a roughly 2:1 o2 to back gas ratio. Obviously each mix will throw it off slightly, lean mix being over 2x, and a rich mix like 40% being way less. No deco algorithm was used, since I didn't know an exact plan...But I've read enough of your posts to know that you're well aware of that ;)

If he's going down to 150, I can see some use for 40% as a deeper deco gas, although I don't see why you would exclude yourself the use of 100%/50% when the two classes are typically combined. Also limiting yourself to nitrogen/oxygen only mixes for 150ft dives seems odd to me, but there's already enough debate on this board about that.

[rjack321]

Yes the deco proc is pretty much useless without adv nitrox.

As far as the helium question is concerned there are a number of folks on here who are overly sensitive to nitrogen narcosis and will have you on He for anything deeper than a snorkel dive but for myself 130ft dive using 30% nitrox and a 50% deco mix is a good days diving.

Actually most of us just get out of the water cleaner on helium than on N2 for say a 35min dive at 120ft. I did a few barely deco dives on air/nitrox back in the day and you sure get out sleepy.

I would do a dive to those depths on 28% or soemthing like that if push really came to shove. But N2 has alot of less than desirable properties esp. once there's alot of slow tissue loading.

I'm only recommending a "more modern" intro deco course prgression because they are readily available now and the OP's 120-130ft goals will probably be 150-160ft within 6 months anyway. Why not get a complete set of tools to make informed choices vs. getting a limited cert which leaves him wondering about what he's missing in his gases and concepts?

[wedivebc]

I am not disagreeing with you. I just think helium should be used with caution and should be used when needed. I am not convinced it is needed in an entry level tech training program and I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal. My personal choice is that I will dive past 100ft on air and under certain circumstances will venture to 150ft without the benefit of helium but when available will always opt for the better gas for the application.




Actually most of us just get out of the water cleaner on helium than on N2 for say a 35min dive at 120ft. I did a few barely deco dives on air/nitrox back in the day and you sure get out sleepy.

I would do a dive to those depths on 28% or soemthing like that if push really came to shove. But N2 has alot of less than desirable properties esp. once there's alot of slow tissue loading.

I'm only recommending a "more modern" intro deco course prgression because they are readily available now and the OP's 120-130ft goals will probably be 150-160ft within 6 months anyway. Why not get a complete set of tools to make informed choices vs. getting a limited cert which leaves him wondering about what he's missing in his gases and concepts?

[SailNaked]

Thanks all for taking the time to comment. I will probably just wait till I get the Time/money and enough points with my wife to do the whole course. I suppose I have enough to keep me busy for a few months, maybe I can take Chatterton's course next April.

[Blackwood]

I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal.

slight hijack, but I find that absolutely ridiculous. If TDI doesn't feel that the class should be taught to the training limit for reasons of safety, they should lower the training limit.

[rjack321]

I am not disagreeing with you. I just think helium should be used with caution and should be used when needed. I am not convinced it is needed in an entry level tech training program and I think it has been made pretty clear by Doppler and others that 150ft is a max limit for deco procedures not a goal. My personal choice is that I will dive past 100ft on air and under certain circumstances will venture to 150ft without the benefit of helium but when available will always opt for the better gas for the application.

Helium is not the enemy, N2 is

(data)...support the rank order of increasing DCS risk (He less than N2 less than Ar)...
Rubicon Research Repository: Item 123456789/2613 (http://archive.rubicon-foundation.org/2613)

[boulderjohn]

I am not sure why we are talking about helium here, since it is not a part of either the Advanced Nitrox or Deco Procedures course. (IMO, it should be, but it is not. TDI holds helium off until later certification levels.)

As for whether you should take one course or both, you really need to take both at the same time. The TDI final exam for Advanced Nitrox has questions that are in the Deco Procedures course, and the TDI final exam for Deco Procedures has questions that are in the Advanced Nitrox course.

If you take the Advanced Nitrox course by itself, it does you no good, since you get no benefit from it. What will you do with the ability to use richer mixes?

If you take the deco procedures course by itself, it will do you no good, since you can't use the rich mixes you need for your deco procedures without advanced nitrox certification.

[rjack321]

I am not sure why we are talking about helium here, since it is not a part of either the Advanced Nitrox or Deco Procedures course. (IMO, it should be, but it is not. TDI holds helium off until later certification levels.)

Kinda my point. Why not take a more comprehensive course now? E.g. UTD has a great "tech1" course using 25/25 + O2 for deco in the 90 to 130ft range. And it can be upsized to 21/35 + EAN50 for deco in the 120-160ft range with a few more days of class - typically taken 3-6months after part1.

Helium is neither difficult nor evil so introducing it sooner is better IMO. If you chose not to use it that's fine, but at least you're educated about when/where its a good idea and why. BTW, to me its way more about low solubility and low density than narcosis issues.

Deco proc by itself is really useless. No higher O2 mixes, no helium either.

[wedivebc]

slight hijack, but I find that absolutely ridiculous. If TDI doesn't feel that the class should be taught to the training limit for reasons of safety, they should lower the training limit.

No, TDI recognizes 150ft in Cozumel is not the same as 150ft off Vancouver Island. This allows the instructor to use discretion based on environmental and other conditions.

[paddler3d]

To the OP's original comment.

A while back I ordered the TDI Deco Procedures text book. Granted, your missing the interaction with and experienced instructor/mentor.

With that said, there was nothing in the book that I wasn't doing already.

I would suggest taking an advanced gas course versus a deco procedure course. At least fore me, that advanced gas course would be a better bang for the buck.

Now my buddy is pushing me toward Trimix vs. Adv. Nitrox. One day I'm leaning towards trimix, and the other towards nitrox. Choices.

Good luck.

[K Mejean]

I am finishing Advanced Nitrox and Deco in a couple of days. I did them both together. Thats how I would recommend it. They really seem to work together very well. They are a prelude to trimix for me and I have enjoyed the classes and the dives very much. I also think that you should have them both before going on to trimix. I somehow doubt that anyone is going to go to the trouble and expense of a trimix course and not do some type of decompression or need the ability to get and properly use O2 for your decompression.

[ucfdiver]

I somehow doubt that anyone is going to go to the trouble and expense of a trimix course and not do some type of decompression or need the ability to get and properly use O2 for your decompression.
I've yet to hear a good reason not to include all 3 in one course. UTD/GUE and many NAUI instructors teach it that way.

[K Mejean]

I've yet to hear a good reason not to include all 3 in one course. UTD/GUE and many NAUI instructors teach it that way.

I think its a good idea to do it that way as well. My instructor is a NAUI and NACD guy. We have done all my tech training together and I will continue with him until I have done all the training I want. So it has been an ongoing progression.

[ianr33]

I've yet to hear a good reason not to include all 3 in one course. UTD/GUE and many NAUI instructors teach it that way.

Agencies have around 700 good reasons to teach Trimix as a separate course :D

[boulderjohn]

I've yet to hear a good reason not to include all 3 in one course. UTD/GUE and many NAUI instructors teach it that way.

I think that is newer thinking. The TDI Deco Procedures book is copyright 2000.

[AndyNZ]

If the course is not meant to be taught by itself why is it? seriously for 11 less minutes in the water enjoying the fish?

The reason that the Advanced Nitrox and Deco Procedures courses have not been combined is that AN is a pre-req for CCR courses, but DP is not.

[AndyNZ]

I've yet to hear a good reason not to include all 3 in one course. UTD/GUE and many NAUI instructors teach it that way.

There are a couple of reasons.

1. There is no Fundies/Essentials in the TDI curriculum. Yes, there is an "Intro to Tech" but it's not a compulsory pre-req for anything. Ask a GUE or UTD instructor whether they want to teach their trimix courses to a student in five days when the student may not have ever worn a twinset before.

For me, AN&DP is Fundies in terms of what I teach. It's a means of ensuring a diver has the basic skills before going on with further training.


2. $270 per trimix fill. The US has the cheapest helium in the world, we are moderately expensive.... you should try some of the remote pacific islands. The deep air argument will run forever, but "deepish" air is a necessity in places. It's a question of where in the 30-40m range you draw the line.

Personally, I'm happy doing 32m on 32% at $20 to fill my twins... as opposed to $270 for a 21/35 mix. I have different opinions when it comes to 55m, but hey. Everyone's line is different.

[SailNaked]

Seems to me that there should be a Deco procedures course that was on deco procedures and deep diving to some limit (limit of air for instance but I would accept 150'). include everything you need to dive past the NDLs. and include deco at 20ft with O2.

Then you have an advanced gas course that has all the speedy gas mixes. (He & O2 < 21% > 40%). I would like to stay on wrecks at 130' in warm water for more than 8 minutes, and need a course to do so. I would pay about 6-700.

As it is I have to take 2 courses and then a third for 3k, such is life, but it will take me a lot longer to save the pennies when I could be diving safely sooner if the course was actually what it was advertized as "deco procedures- certified to dive to 150ft" maybe TDI should change it up a little, "deco procedures - 1/2 the course to be certified to dive to 150 ft." why are they offered seperately if you must have both? I do not have other alternatives in Houston or Austin that I know of.

[rjack321]

Seems to me that there should be a Deco procedures course that was on deco procedures and deep diving to some limit (limit of air for instance but I would accept 150'). include everything you need to dive past the NDLs. and include deco at 20ft with O2.

Then you have an advanced gas course that has all the speedy gas mixes. (He & O2 < 21% > 40%). I would like to stay on wrecks at 130' in warm water for more than 8 minutes, and need a course to do so. I would pay about 6-700.

As it is I have to take 2 courses and then a third for 3k, such is life, but it will take me a lot longer to save the pennies when I could be diving safely sooner if the course was actually what it was advertized as "deco procedures- certified to dive to 150ft" maybe TDI should change it up a little, "deco procedures - 1/2 the course to be certified to dive to 150 ft." why are they offered seperately if you must have both? I do not have other alternatives in Houston or Austin that I know of.


My wife has GUEF ~3-4 yrs ago in a single tank. And GUE Cave1 in doubles. And took UTD Tech1 this past summer. She has had some great 25-30min dives in the 120-130 range on 25/25 with O2 for deco.

Maybe the TDI shoe just doesn't fit. The reality is that Austin isn't exactly a diving/training hub anyway so why not get a bit of training in during your dive travels?

There are plenty of good instructors offering courses that meet your needs in FL, CA, and elsewhere.

[Blackwood]

No, TDI recognizes 150ft in Cozumel is not the same as 150ft off Vancouver Island. This allows the instructor to use discretion based on environmental and other conditions.

Is there a minimum depth to which is must be taught? Or can students who live in cold murky waters potentially go through a deco course only doing simulated decompression?

[AndyNZ]

Is there a minimum depth to which is must be taught? Or can students who live in cold murky waters potentially go through a deco course only doing simulated decompression?

For AN&DP there is no minimum depth. Most "critical" skills need to be conducted shallower than 30m.

Most instructors I know tend to aim for 70-80% depth of the course limits, irrespective of the course.

You can still do a good DP course if you limit it to a max depth of 35m - the challenge is getting students to realise that 45m is a big dive, and a big step up from 35m.

[AndyNZ]

As it is I have to take 2 courses and then a third for 3k, such is life, but it will take me a lot longer to save the pennies when I could be diving safely sooner if the course was actually what it was advertized as "deco procedures- certified to dive to 150ft" maybe TDI should change it up a little, "deco procedures - 1/2 the course to be certified to dive to 150 ft." why are they offered seperately if you must have both? I do not have other alternatives in Houston or Austin that I know of.

You can do DP as a separate course, you just don't get the value of doing it in conjunction with AN.

AN is separate as it is a pre-req for CCR courses that require O2 knowledge without deco knowledge.

You could always look at other agencies, DSAT, IANTD etc.

[ianr33]

Although they are technically 2 separate courses Advanced Nitrox and Deco Procedures are normally done at the same time. In practice it is difficult to tell which course is which.You do what is essentially one course and come out of it with a card good to 150 feet and 100% O2. Combined cost is probably somewhere around $600 ??

There are now at least 2 instructors in the Austin area and probably many more in the rest of central Texas.
Lake Travis is very convenient. It is also pretty deep dark and cold (or at least it will be deep again if it keeps raining) While I would not recommend diving in these conditions to 150 feet on air, many people will do 120-130 (DIR types flame me now ;) )
A 130 foot dive through the trees in Travis feels like a much "bigger" dive than a 150 foot dive in Cayman

[Scott L]

Kinda my point. Why not take a more comprehensive course now? E.g. UTD has a great "tech1" course using 25/25 + O2 for deco in the 90 to 130ft range. And it can be upsized to 21/35 + EAN50 for deco in the 120-160ft range with a few more days of class - typically taken 3-6months after part1.

Helium is neither difficult nor evil so introducing it sooner is better IMO. If you chose not to use it that's fine, but at least you're educated about when/where its a good idea and why. BTW, to me its way more about low solubility and low density than narcosis issues.

Deco proc by itself is really useless. No higher O2 mixes, no helium either.

Very logical statement. What are the basic diffirences between GUE Tech 1 and UTD Tech1 and the agencies in your opionion? No instructors in east coast USA? GUE/UTD agreement? :dontknow: Odd!

[Red Sea Shadow]

Adv. nitrox alone doesn't even get the ability to switch gases, nevermind the lame 21% to 36% balony.
Advanced Nitrox alone gets the ability to switch gases up to 100% O2 within the non-deco limits.

[Red Sea Shadow]

Although they are technically 2 separate courses Advanced Nitrox and Deco Procedures are normally done at the same time. In practice it is difficult to tell which course is which.You do what is essentially one course and come out of it with a card good to 150 feet and 100% O2. Combined cost is probably somewhere around $600 ??
Advanced Nitrox alone certifies the student to use up to 100% O2 mixes within non-deco limit. Deco Procedures introduces the student to decompression diving.

[Rhone Man]

To be honest, they might as well consolidate Adv Nitrox / Deco Procedures into one course. I have never met anyone who didn't take them together.

Amen on the 150 feet in the Caribbean is not the same as 150 feet off Vancouver Island concept. Diving deep in Caribbean waters involves a lot less task loading. For one thing we don't need to carry lights or wear drysuits. I did my 180' checkout dive for TDI Extended Range in a shortie.

[ianr33]

To be honest, they might as well consolidate Adv Nitrox / Deco Procedures into one course. I have never met anyone who didn't take them together.


Believe the reason for them being separate is something to do with rebreather training. Advanced Nitrox is a prerequisite but not Deco Procedures.

For OC they might as well be one course.

[Red Sea Shadow]

To be honest, they might as well consolidate Adv Nitrox / Deco Procedures into one course. I have never met anyone who didn't take them together.
People who want to climb the technical diving ladder usually combine them in one course. However, others prefer to extend their dive times without decompression.

[Rhone Man]

Believe the reason for them being separate is something to do with rebreather training. Advanced Nitrox is a prerequisite but not Deco Procedures.

For OC they might as well be one course.

Sorry - I see that you posted that earlier in the thread - sorry for jumping in without checking.

[boulderjohn]

To be honest, they might as well consolidate Adv Nitrox / Deco Procedures into one course. I have never met anyone who didn't take them together.


I think the fact that you need the book for one to take the final exam for the other makes it a very practical policy.

[Van Isle]

I think the fact that you need the book for one to take the final exam for the other makes it a very practical policy.

That's a fault of the training material. The fact of the matter is that there are people who desire the information/cert. provided by one course or another and not both. In 3 seconds I can think of gas blenders, scientific divers at shallow depths, military/paramilitary swimmers on 100% O2, non-overhead rebreather divers. Imagine paying twice the price for a course from which you only needed half the info? Methinks some have need of one or the other, and some have need of both courses.

YMMV (which is why there are options)

VI

[boulderjohn]

That's a fault of the training material.

I agree, but the training materials are part of the course. If you are taking the final exam in one course and find that you need to have information from the other course, then that is still a problem, regardless of the fault. The simple solution would be to change the training materials, and perhaps in time that will happen. The current training materials are only about a decade old, so I guess we just have to give it enough time to be fixed.

[Red Sea Shadow]

TDI Advanced Nitrox and TDI Deco Procedures are two different courses. They are not depending on each other. The exams do not require extra material other than the course material.

[boulderjohn]

TDI Advanced Nitrox and TDI Deco Procedures are two different courses. They are not depending on each other. The exams do not require extra material other than the course material.

Interesting. That's not my memory. I took both exams the same night, and the fact that we had to switch books was a topic of amused conversation.

[Red Sea Shadow]

Interesting. That's not my memory. I took both exams the same night, and the fact that we had to switch books was a topic of amused conversation.
I have both exams in front of me now; Advanced Nitrox version 1.2 and Deco Proc version 1.1. Neither exam requires other material than the course's manual.

[Michael_Lambert]

I recently wrote both exams and each had answers to its specific training manual. Now i did take the courses using the 2009 training materials i can't comment on the older 2001 materials used until recently, which some instructors/shops still are phasing out.