Like @RyanT, I got my XR card as part of my TDI Trimix training.
I feel like the benefit was just to have the experience of diving to 180 on air in a somewhat controlled environment - i.e. with an instructor to help me if I needed it. I wouldn't have bothered to get the card by itself.
I have been under the impression that repeat experience will, well, maybe not cause you to experience less of it, but at least make you better able to operate effectively while experiencing it. It seems, to me, to be directly analogous to how I can drink 6 beers now, and not seem, to the casual observer, drunk at all. But, the first time I drank 6 beers, it was obvious to everyone that I was drunk.
I have been to 190 with 20% helium and been very narked. I have been to 180 on air and not felt very narked at all.
It (being narked) is certainly not a reliable, repeatable thing. It could happen when you are not expecting it at all. It seems to me like a good idea to have some direct, personal experience with it (in a controlled environment, of course). At least, a good idea for anyone that is planning to dive deep. Less important for people who will be doing NDL dives within standard recreational depths.
I feel like the benefit was just to have the experience of diving to 180 on air in a somewhat controlled environment - i.e. with an instructor to help me if I needed it. I wouldn't have bothered to get the card by itself.
I see the intent behind it but based on what we understand about Narcosis today, you can't train someone to manage it neither will repeat experience cause a person to experience less of it. So it a drill in understanding how much impairment you will experience at 180 feet depth? If a person chooses to dive to 180 feet on air (for whatever reason) how will this course help?
I have been under the impression that repeat experience will, well, maybe not cause you to experience less of it, but at least make you better able to operate effectively while experiencing it. It seems, to me, to be directly analogous to how I can drink 6 beers now, and not seem, to the casual observer, drunk at all. But, the first time I drank 6 beers, it was obvious to everyone that I was drunk.
I have been to 190 with 20% helium and been very narked. I have been to 180 on air and not felt very narked at all.
It (being narked) is certainly not a reliable, repeatable thing. It could happen when you are not expecting it at all. It seems to me like a good idea to have some direct, personal experience with it (in a controlled environment, of course). At least, a good idea for anyone that is planning to dive deep. Less important for people who will be doing NDL dives within standard recreational depths.