Tdi equivalent ratings with other scuba diving agencies sdi tdi erdi gas zone

A few months ago, we released an article that broke down all of the SDI Diver certifications and what the most popular agency equivalent ratings were. You can view this article HERE. The goal of posting that equivalency chart was to provide a resource for divers and dive professionals to help navigate the web of diver certifications.

This has been a popular blog post that has proven to be a valuable resource, and we have received many requests to create a similar page for TDI ratings. First impression would be that this should be fairly straight forward, however when you look a bit deeper, you will quickly see the challenges it presents.

First and foremost, not all technical diver ratings are created equal. Every training agency takes a different approach when it comes to the flow path for creating technical divers. Throw in helium, rebreathers, cave diving, sidemount, etc. and the flow path begins to look more like a tangled complicated web of options. And that’s just for each agency; now imagine crossing back and forth from one agency to the next, and it becomes a nearly unmanageable maze. But we’re going to try to break it down for you here.

Before we get into the different ratings from different agencies, it’s important to discuss the philosophies TDI holds for all technical diver training. One of those philosophies is based on prerequisites. If you are unfamiliar with this aspect of TDI’s training flow path, please reference the article recently posted regarding prerequisites HERE. Aside from prerequisites, TDI also strongly believes that each course should be focused on one specific aspect of diving. Whether it’s a new piece of equipment (i.e. a rebreather) and environment (i.e. a cave), OR extending the diver’s range (depth, distance, decompression obligation) for that specific piece of equipment or environment. These aspects are NEVER combined into a single course.

For example, if you are not a trained decompression diver, your first rebreather course will not qualify you to conduct decompression dives using that rebreather. You will have to complete the entry level rebreather course, get some experience on the unit, then take a CCR decompression diver course (Air Diluent Decompression or Helitrox Decompression). This ensures the student is focused on developing critical equipment related skills in an environment and conditions that they are already very comfortable with. The requirements and prerequisites for each situation (depth, decompression, and overhead environments) are clearly defined in the TDI Standards and Procedures.

However, I’ve been seen over the years divers that fail to move up the GUE ranks (by inability most of them, but some by other restrictions) taking another path to reach a “depth” goal – opposing the ethos and objectives of GUE. Not saying that the other agencies courses are easier, but just that I’ve noticed this movement over the years with some GUE divers that either failed Fundies, Tec1 or achieving a Tec pass in Fundies.

I’ve seen people saying “you should chose the instructor rather than the agency”, which I tend to agree for some agencies but not all… The agency should/must ensure its instructors quality and standards, failing to do so divers have huge problems taking the right courses to achieve their diving objectives. This table seems to make it even more complicated.

By your comment, I seem to understand the criteria, i.e. numbers and “features/skills”… Also, I do understand that putting something like this together may be highly complex, as I believe passing criteria, instructor quality ranking ratios, etc., should be considered. However if some cannot achieve that, in my humble opinion/view one should not develop such lightly minded comparison.

As a GUE, IANTD and PADI certified diver I know enough about many of these classes to know that the table of equivalencies should be taken with a massive grain of salt. I won’t go into details because that’s seeing the trees not the forest. I’m at a point where there are no instructors around me to continue my training with IANTD or GUE and there are few TDI or PADI instructors around me and none of them really know me as a diver. I don’t want to come across as a card collector trying to skip a level and I don’t want to go back and repeat a level doing stuff I already know. Regarding the GUE Rec 3 and IANTD Advanced Nitrox vs TDI Advanced Nitrox, I don’t think I can agree. There are some limits placed on these cards but both of those divers are doing accelerated decompression dives that is far in excess of TDI AN or PADI Tec 40. Another way to look at it is that IANTD allows an AN diver to take Normoxic Trimix next. TDI would have you go back and take deco procedures. I would hope that it’s possible to get evaluated by a TDI instructor and if suitable skip deco procedures or take a very short version of it (to brief any differences in protocols/procedures) and then proceed on to Trimix or Helitrox if desired (which I think is comparable to IANTD Advanced Recreational Trimix ).

I don’t really see this as a problem at the recreational level classes. With the exception of Master Diver meaning one thing to NAUI and something else to almost everyone else an OW, AOW, Rescue diver is clearly understood and transferable. Reply