Posted by joe r on June 18, 2001 at 05:29:29:
In Reply to: Re: 160' on nitrox? - Hope you're fireproof! posted by MHK on June 15, 2001 at 10:02:36:
The extended range classes are not about doing deep air but rather more extensive dive planning, procedures, and contingency planning. Diving in the 130ft range satisfies class requirements.
ANDI requires this class prior to trimix TRaining since their trimix class is 100meters max. When it comes to deco violations AIr is much more forgiving than helium, also this class exposes the student to multiple gas switches. TDI now allows intermediate trimix (2oo fsw wax)for diver level without this class but its still a requirement for trimix instructors.
I do believe students should at least have had some exposure to narcosis. How many trimix divers out their have trimix in their bailout bottles (dives wher air PO2 would be <1.6) ??
Someone who had a problem and was forced to bailout onto a narcotic mixture there would be a big problem, the gas switch hits you very fast.. I don't advocate diving to 180 on Air (tdi ext range max limit) I advise those wishing to go to that depth to seek out trimix.. Different divers deal with narcosis differently, I function adequately for most types of dives in the 150ft range on a non helium mix, I wouldn't dream of doing a penetration without He though at the same depth.