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Somebody stated: Technical trimix is a deep air course. I believe he's right -- this course is definitely bordering on the "deep air" that most most of us agree to avoid. My deepest "technical nitrox" dive was a nitrox 23 dive to 160'. Of course, 23% oxygen is a ridiculous mix since it's not worth the effort, but the point was to practice making EAD calculations. The purposes of "technical nitrox" are to learn gas management, practice swimming with a heavy rig and practice gas switches. My question to the board is, what do you think would be the preferred depth limit? We definitely do not need "level stoned" yet we do want a realistic task loading, deco obligation included. I would suggest 130' as a good target depth for "technical nitrox" -- it's enough to provide a realistic training scenario for future trimix divers, yet narcosis is not a problem. However, as a physiologist I know that narcosis can be measured at depths shallower than 100'. If we demand no narcosis whatsoever, we really have to pull back. What is a reasonable EAD for a trimix dive? Ask some and the answer is 200' -- ask others and they go 100'. Ask me and you get 100' - 130'. I believe the "technical nitrox", "extended range air" or whatever you call it should have a target depth matching the EAD you will prefer as a trimix diver. Learning the toting, configuring, switching and balancing the rig does not depend on going deep. Actually, some of the best training may be to swim sidemounts for an hour at 20'. I think most of the current philosophies are based on giving students a taste of narcosis and prove the need for trimix. I believe most of today's trimix divers have thorough knowledge of nitrogen narcosis from past experience. Discussing this with some friends, the opinion was voiced that past deep air experience might be an advantage. I half-heartedly disagree. Sure, it may be sort of an advantage to have been there and know what to avoid, but I don't think new trimix divers need to go through the same phase of trial and error. In retrospect, an advantage but no prerequisite, and definitely not the direct way to learn trimix. We need to build a record and gain experience underwater doing what we're supposed to do. If trimix is the tool of the trade, it makes a lot more sense to log more trimix dives than it does to practice deep (or even deepish) air dives. My conclusion: 130' is a good target depth for practicing and preparing for trimix. What do you say? -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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