johndiver999
Contributor
Does the reduandnt gas supply encourage the diver to extend exposure beyond what they would do without the redundancy? If so that violates the condition of the gas/equipment being a true contingency. It becomes "wag the dog." That is "I'll do something I'm otherwise not comfortable/confident doing/trained for because if I f*** up/get in over my head I have my redudant gas to bail me out."
A redundant air system is used primarily by divers who are often solo and who are not confident that they can reach the surface safely following a failure of the scuba system. A properly selected redundant system provides the diver a means to make a safe ascent should a primary failure occur.
It is quite obvious to me that there is some threshold of depth and dive time, where a CESA becomes impractical or unsafe. That threshold varies for different people and different conditions, but it exists for everyone.
My personal threshold is a no deco dive around a depth of 50-60 feet. Deeper than that, I am generally using a redundant system when solo diving. I generally won't go deeper than that without one.
Why would my decision to take a pony bottle on a 100 ft dive and not on a 40-ft one, "violate the condition of the equipment being a true contingency"? Perhaps you can clarify your reasoning on this concept?