kafkaland
Contributor
I got very recently OW certified, and then took the nitrox course (PADI). And I appreciated having an instructor who was broader than just being qualified to teach that course and recite the manual. In fact, what the nitrox course is concerned, the course materials plus some background knowledge of physics, physiology, and common sense is fully sufficient to pass the course. But where I got the extra information that I didn't already knew was from a question that I asked after he made a throw-away remark along the lines of that any gas mix is always a trade off. So I inquired about helium, which I knew very little about. And since he is also a tri-mix instructor, he gave us a brief outlook into what helium does - and doesn't. I sort of knew that you can get bent on helium, but having that confirmed was good. And, more importantly, it hadn't really been on my radar screen that rapid off-gassing also means rapid on-gassing, limiting its usefulness for short dives, and the need for precise control of ascent rates as a consequence of the rapid gas exchange rates. Now, this doesn't have any practical implications for my diving in the next few weeks or months, because I'm nowhere near ready for going tri-mix, but it changes my outlook on this, as it's not as simple as "just add some helium", as some seem to make it. That discussion, going beyond the nominal course content because of a well-qualified instructor, was for me the most interesting piece I got out of a course that I took mostly for the card.