John Bantin
Contributor
Some people experience narcosis at quite shallow depths. My experience of doing 55m+ (180ft +) regulator comparisons over two decades using air (the most problematic gas) for UK Diver Magazine is that I had always to be careful to choose participating divers who were unlikely to be affected by narcosis at that depth because they often did it (ie experienced deep divers.) In every case, my test divers wrote coherent notes on the performance of each regulator at depth, which corresponded with the findings of others - so I was confident of the veracity of the tests and the absence of narcosis with them at that depth. Originally, I took photographs on a Nikonos V with film while the tests were undertaken and found that I was able to be proficient with the techniques needed so I guess I too could handle it. (Later digital cameras made it an almost thoughtless process!) Some people can go very deep without experiencing narcosis (Bret Gilliam and Joe Odem come to mind). When we first dived the wrecks at Bikini Atoll (180ft), we only had air. There is no rule. Narcosis affects different people in different ways.