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.

[Saspotato]

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 !!) :)

[Valhalla]

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

[Valhalla]

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.