TDI Nitrox - differences with PADI

[Sias]

I recently contacted my LDS Owner (from a PADI shop, though he was just certified as an SDI/TDI instructor) and told him I would be in the shop in a couple of days to pick up a Nitrox book for something to do in the off-season, being PADI certified, I assumed I would pick up their version. He stated that he would order me a TDI Nitrox book as he believed it would be more valuable. My question is simply, what are the major differences in TDI's teaching of Nitrox, and PADI's teaching. I understand the differences in recreational and technical. But don't understand how there could be a large difference between the two. Are the formula's the same?
Now, I have not taken a nitrox class, and I am not by far a tech. diver, but I do enjoy math, and I have browsed the Boards long enough to understand the theory and usage of nitrox, so please keep the terminology simple.

Thanks!

On a side note: I am looking to becoming a DM in the near future...not a zero to hero kind. (I need way more dives). Is there major differences between PADI and SDI/TDI DM's, or as a DM does it not really matter what your certifying agency is.

[zider]

I recently just completed the TDI EAN course and I discussed this very thing with my instructor. His overall take was that the TDI course is more technical with respect to focusing on the basic physics at work and also the calculations that go with it. The PADI course is designed to get you up and running quicker by focusing on the main points needed, but it doesn't go into the technical detail as the TDI course does.

I also noticed you are a fellow Hoosier. What area of the state are you from?

[RikRaeder]

Out of curiosity, what are the more technical points that TDI covers?

[HowardE]

As I recall... PADI doesn't touch on Dalton's law at all; SDI covers that in their book. A simple concept that makes partial pressure of gasses easier to understand.

Understanding how partial pressures work, is one of the important concepts for understanding nitrox diving. Nitrox diving is also a building block for technical diving, and for rebreather diving. Having a clear concept of nitrox is therefore important.

[RikRaeder]

Thanks

[Divin'Hoosier]

On a side note: I am looking to becoming a DM in the near future...not a zero to hero kind. (I need way more dives). Is there major differences between PADI and SDI/TDI DM's, or as a DM does it not really matter what your certifying agency is.

A DM is the first rung on the professional ladder. Therefore, you are going to want to go with whatever agency you see yourself working with. Typically that's the agency your LDS is affiliated with. As a DM you work for/with someone ... a shop, one or more instructors ... often times both. You'll need to be certified through the agency they teach under.

Becoming a divemaster is quite different then the two courses you've already completed. It's more of a mentorship working under one or more instructors. Once you've completed the program and purchased liability insurance, it's very common to then become a divemaster assisting the instructors who did your DM program. Essentially this means the decision of which agency to use is really made for you. It's based upon your LDS and/or the instructors you'll be assisting.

One bit of advice. It's perfectly fine to have goals. It's actually great to see and I wish you all the best! However, with less then 24 dives (based upon your profile), keep your long-term goals in mind but focus short and mid-term on diving frequently and building your foundational skills in many different environments before moving onto DM. A solid base of experience is essential to not only complete a divemaster program, but more importantly to be a good DM once you're done.

[Brian Sharpe]

My LDS also teaches the TDI Nitrox course rather than PADI, the instructor's reasoning is that the PADI course is an end unto itself as one of the PADI specialties whereas the TDI course is the foundation of TDI's open circuit training (adv nitrox, deco, etc.)

[Doppler]

Not familiar with PADI's course but can explain something about ours. TDI Nitrox course goes more deeply into the laws and calculations behind the theories while SDI's is about diving nitrox with a computer and is aimed at being a simple study.

As a swift overview, think of the difference in this way. Ask an SDI nitrox diver the Maximum Operating Depth of a mix and she will consult a table or her computer. Ask the same question of a TDI certified diver and she will pick up a calculator.

[tmolm69]

And the books are alot less in cost, as well the above stated

HQ has a new DM program it kicks @!! (its also on-line) you need to take a look!!!

[AndyNZ]

Having a foot in both camps, it would actually be very hard to give a definitive answer... it depends very much on the instructor.

The PADI course does go into calculations for MOD, partial pressures, EADs etc, at the same time it also goes through tables use for the same. To my mind, the PADI course doesn't always present the calculations in the most straight forward manner - e.g. MOD calculation uses the formula MOD = (14 / fO2) -10.

To my mind (though everyone is different) it's easier just to think in ATA rather than metres and just use the T equation (aka Daltons Diamond, the magic circle etc)... but there's nothing to stop this being taught in the course.

The advantage that TDI nitrox does have is that you are more likely to get a technically minded instructor who can answer questions that extend your knowledge.

There is a classic question in the PADI course where most students attempt to answer the question using the wrong table - and a rounding down of depths (from 12.7m to 14m) results in a huge difference in available bottom time for the dive. Many PADI instructors come to the conclusion that actually pressure groups aren't interchangeable across the different versions of the RDPs and that's that. A TDI instructor is more likely to realise that the rounding changes the controlling compartment of the underlying decompression model.

With the right instructor, either course will be fine and won't limit any future aspirations. If you don't know whether you have the right instructor, go TDI.

[Rhone Man]

The nice thing about the TDI books is that you get pages and pages of useful tables in the schedules at the end. (The bad thing about them is, with the possible exception of Advanced Wreck, most of the ones I have seen could use a pretty aggressive editor to clean up the main body of the text.)

I have never seen a tec manual from PADI. Their Enriched Air manual is pretty enough, but it takes a long time to make a few basic points.

[Sas]

I did TDI Nitrox at a shop that usually does PADI training, think their reasoning was the same. I think my nitrox training was far more detailed than my buddy's, particularly in regards to dive planning. We had to do detailed dive plans and work it out all ourselves without tables. The teacher basically said if we wanted to use tables after the class that's cool but in class we could only use air tables and the formulas. The teacher also talked for a while on advanced nitrox diving + trimix diving and discussed some of the issues around that, he talked about gear requirements for more technical diving, talked about some of the things to consider when decompression diving, and went into a lot of detail around the physiology of nitrox diving.

Compared to my buddy, I think I got a lot more out of my nitrox course than he did. But, yea I might just have had a good instructor and my buddy not so good, not sure.

[djones103]

As stated by several posters, DM is a professional step forward. As a professional, you need to understand Nitrox at a professional level. That is, the physics and theory of it. The TDI class will get you well acquainted with that. I have both certification and teach Nitrox for PADI. This is a great class for the recreational diver who plans to dive on holiday. There is nothing wrong with a DM who only has the PADI EANx certification; however, would you consider yourself a subject matter expert (aka Dive Master) knowing there was a more in depth Nitrox course out there. My vote is for the TDI class.

[200 Bar]

If I remember correctly there are no dives to make in the TDI course..So from a shops POV time is money .....

[Rhone Man]

If I remember correctly there are no dives to make in the TDI course..So from a shops POV time is money .....

I thought that must be wrong, but it seems you are correct:

TDI basic and advanced nitrox, decompression procedures, entry level and advanced trimix courses with instructor Mark Powell (http://www.dive-tech.co.uk/tdi%20courses.htm#basic)

[RJP]

If I remember correctly there are no dives to make in the TDI course..So from a shops POV time is money .....

PADI no longer requires dives either, I believe.

[200 Bar]

PADI no longer requires dives either, I believe.



Hey your right..!!! ....I just looked...(I guess I live in a cave !!) :)

[Scott L]

The nice thing about the TDI books is that you get pages and pages of useful tables in the schedules at the end. (The bad thing about them is, with the possible exception of Advanced Wreck, most of the ones I have seen could use a pretty aggressive editor to clean up the main body of the text.)

I have never seen a tec manual from PADI. Their Enriched Air manual is pretty enough, but it takes a long time to make a few basic points.

I have never seen a tec manual from PADI either but several tec instuctors declare them to be too verbose. Conversely, TDI's are consise and to the point IMO. If my advanced nitrox/decommpression manuals were "cleaned up" to any great extent they could then fit onto a single page flyer. :D

[Scott L]

PADI no longer requires dives either, I believe.

I am in the process of getting new girlfriend a proper dive education and confirmed this fact. They did offer a charter dive package though but not required...

[Newbie100]

As I recall... PADI doesn't touch on Dalton's law at all; SDI covers that in their book. A simple concept that makes partial pressure of gasses easier to understand.

Understanding how partial pressures work, is one of the important concepts for understanding nitrox diving. Nitrox diving is also a building block for technical diving, and for rebreather diving. Having a clear concept of nitrox is therefore important.
That's the only difference Ptotal= P1 + P2 + P3... Total pressure equals the sum of all of the partial pressures & that there is an inverse relationship between volume and pressure in an enclosed system with a constant . As volume decreases pressure increases and vice versa. If that the only difference between PADI and TDI you are not exactly selling TDI.

[Pullmyfinger]

I have taken both the Padi and the TDI Nitrox courses. I had to Take the TDI class due to the Padi course not being accepted (by my instructor) as a prerequisite for Advanced Nitrox/Deco procedures.
That being said, the Padi course was adequate in my opinion.
TheThe main differences were that there is much more time and material in the TDI class that is devoted to understanding partial pressures. As was previously mentioned, Dalton's Law and the "T", or "Dalton's Diamond" along with more time spent with formulas are part of the TDI course. None of this is really part of the PADI course. The PADI course does devote some time working the formulas so that you'll have an understanding of partial pressures, it's just explained on one page of their book and presented by the instructor.
The TDI course just spends more time calculating best mix, dose, and depth relationships.
The PADI course covers Enriched Air computers in addition to tables use. The TDI class never really covered computers at all, the emphasis was on tables and formulas.
The PADI course was adequate. The TDI course offers a little more to build on.
To be honest, there really wasn't anything that I didn't already have an understanding of from having taken the PADI class. Things were covered in a little more detail with my TDI instructor.

I will say that my experience with my PADI instructor was minimal. I read the entire book, worked all of the problems, and noted next to each problem what page the information that related to that question could be found in the book.

This was a good thing, because there was really no lecture at all.....my "class" consisted of having my answers graded. There was only a quick discussion of the subject matter.
How to analyze a tank was only explained, never demonstrated. In this regard, my TDI class was a significantly better experience.

I'm sure you would have a more detailed class if you found a PADI class somewhere else. Because as many on this forum love to point out......it's not the agency, it's the instructor.:eyebrow:

As I stated, the PADI book was good, and I was able to learn by reading, working the problems and formulas, and just taking an active interest in it.

Another thing I have noticed in regards to nitrox. I've been to Yap and Palau, and I've noticed during both trips that no other divers ever analyzed their tanks. Analyzers were always available, but nobody ever checked their tanks????

Regards,
Mitch

[mddyver]

Another thing I have noticed in regards to nitrox. I've been to Yap and Palau, and I've noticed during both trips that no other divers ever analyzed their tanks. Analyzers were always available, but nobody ever checked their tanks????

Regards,
Mitch

Sigh......

I've taken both courses and teach one frequently to a wide range of students with varying levels of competency in algebra and basic physics. I'm also a gas blender and have worked at a very high volume dive resort that filled scores of nitrox cylinders daily.

At some point during the discussion, usually about 20-25 minutes into the class, I inform the students that if they can recall only two points and two points only, they are:

1. Don't plan a dive that exceeds your MOD.

2. If you have any reason to suspect the cylinder you are about to dive has ever contained anything other than air, personally analyze your gas. Never let any dive leader, SO, dive buddy, or situation, etc. pressure you into skipping this step.

What can you do?

Mike

[Pullmyfinger]

Hi Mike,

I'm sure it's frustrating for instructors, investing the time and effort leading horses to water.
Some of us horses actually do drink.;)

-Mitch

[romad119]

in Palau. But once the wife and I analyzed our tanks, the rest of the boat seemed to remember that this was a step they should be doing and joined in.

[kaerius]

I did it PADI, and my natural reaction is also to go for the calculator before the tables(except for O2 exposure, table only on that)... however I was in one of the last batches of students to use the old manual, from what I've heard, the formulas are gone in the new one(so I guess it's a lot like the SDI one), focusing instead on computers and tables.

On the other hand I did it at the start of my divemaster course and then continued on to OWSI, so I have quite a firm grasp of partial pressures anyway.

[sallyliao]

Thanks

[knowone]

TDI was actually training, peeps nitrox, well before padi even had panties to pee in, about it.

[deepair]

I teach all three. PADI, SDI, and TDI Nitrox. SDI and PADI Nitrox are about the same. Know what is in your bottle, what the MOD is and set your computer. TDI Nitrox is more like the Nitrox I learned from IANTD years ago. It gives a lot of focus on the use of the formulas. This helps the student looking to go further and take the Advanced Nitrox and Deco Procedures a much better foundation. I was not nor am I an algebra expert. Heck I have enough trouble helping my kids with their Homework. But if presented from a good instructor, the formulas make sense and are not hard to use. I actually have 3 DM candidates from other instructors who are planning on taking the TDI nitrox even though they have PADI nitrox. Go figure.

[RTee]

As others have said before...a lot of the training is dependent on the instructor you get. I did my Nitrox qual through PADI but with an instructor who bwas very tech minded. Interestingly enough...not only did he have me read the PADI manual but also he lent me one from TDI. We then sat down and went through all the formulaes he could think of.when I did my PADI DM course, he also threw additional reading materials to augment the theory of decompresssion aspect of the course...such as TDI Advanced Nitrox and TDI Deco procs.

Not too long ago I completed those two courses as part of a combined package and my instructor did recognize my PADI Nitrox course as meeting one of the course prerequisite.

[tddfleming]

Just finished my TDI Nitrox last night. When I took Padi OW last year, tables were not taught unless you stayed after for a few min and the inst went over them. But had not looked at tables since. I have no knowledge of the Padi Nitrox course to compare to, but I like the TDI book, I did not feel like I was reading an info commerical. I spent a fair amount of time learning the tables before class. I felt that this was the first course that covered any dive planning that I have taken to this point. While we have been teaching ourselves some of dive planning this was the first course that started down that path. The one issue we had with the book (I don't have the book here at work with me) but when it starts into examples of tables, there are three examples that are wrong. Which begins to screw with your head, as I tend to assume they should be correct. The scary part, is that we confirmed our suspension that they were wrong to the inst and it appeared that this was the first time that it has been brought up. Our class does involve 2 dives, but not inst lead. I have to admit, finding a good shop and inst has been the hardest thing around here. There are days that I think it would be much easier inventing some rare formula than finding a good LDS and inst.

Edit::

It was made clear in class to always stay within your MOD and to ALWAYS check your own tanks and to do it upon pickup from LDS. Is it common practice to have your own analiyzer or use the shops upon pick up??

[D_B]

Having your own analyzer kinda depends on your funds and how much and where you do your diving ... here it's common to have an analyzer for you to use to check your tank when you have it filled, and usually on the dive boat as well

I have not gotten one yet, but there are economical options, if you can solder, the El Cheepo II kit is $100 ... that is one I'm likely to get.


My PADI class was pretty involved , and the the paper dive scenarios my instructor gave to me were ... stressful

[Centrals]

I had no problem to start IANTD Adv Nitrox and Deep Air training with just PADI's Nitrox certification.