We are often asked why we have two nitrox programs, one SDI and one TDI, and why would someone choose to take one course over the other – or even consider both? The answer is simple:
SDI (Scuba Diving International) focuses on the entry-level sport diver while TDI (Technical Diving International) focuses on the more advanced diver looking to develop their knowledge and adventure into technical diving.
Though both have a nitrox course that covers nitrox mixes from 21% to 40% for no-decompression dives to 130 fsw/40 msw, they have a very different level of content, and target audience.
SDI Computer Nitrox builds upon the Open Water course by giving simple and clear guidelines on the use of nitrox for entry-level diving using a dive computer. As all SDI programs require the use of a dive computer, the Computer Nitrox course allows students to program their PDC (personal dive computer) for a given mix, say 32%, and retain the standard diving practices that they were taught in their Open Water Course. EAD tables allow equivalent air depths to be used if using an air-only dive computer whilst the introduction to oxygen toxicity focuses on a simple single PO2 limit using a look-up table in an easy and straightforward manner. This is a very simple course that can be taught using the manual (with no exams, just some easily completed knowledge review questions at the end of each chapter) or via the eLearning options. It is the SDI Computer Nitrox course which is regarded as the equivalent to entry-level nitrox courses from other sport training agencies.
TDI Nitrox is a much more in-depth program, designed for the diver looking for a strong background in nitrox or considering taking additional technical diver programs. EAD, oxygen toxicity, exposure limits, and O2 exposure percentage uptakes and decreases are looked at in much more detail. Chapter reviews and an exam are required. This program is beyond the scope of the traditional sport agencies’ nitrox programs and is regarded as equivalent to other technical agency programs.
Though you can use either the SDI or TDI Nitrox course as the pre-requisite to the TDI Advanced Nitrox program, divers with the SDI Computer Nitrox background have a much greater learning curve and often Advanced Nitrox Instructors find it best to give the TDI Nitrox exam to these candidates at the start of the program so they can see the level of knowledge they are lacking.
Choosing which nitrox course to take is really dependent upon what you are looking to do with your diving. If you are a more sport-orientated diver, then the SDI Computer Nitrox course is probably the most suitable program. If you are a diver who wants a more demanding program, then the TDI program fits better.
So, SDI or TDI Nitrox? Really, when it comes to nitrox, you should take the course that fits your needs. Not every brand of mask fits all divers – the same can be said for your training programs.
