rjack321:
I would say "a decompression obligation is incurred if a direct ascent to the surface exceeds the maximim allowable value, aka M-value, in a compartment".
Actually, when at depth, most if not all computers ignore future ascent time in the NDL calculations and just simply show decompression obligation/NDL time remaining based upon whether or not the current compartment pressures exceed the surfacing value M-value limit, aka M0. This is why it is pretty common to have a couple minutes of deco stop called for when at depth, but then to have the deco stop go away during the ascent. OTOH, if one does tooooo slow of an ascent, the deco obligation will increase.
The oft-repeated statement of "computers don't give credit for deep stops" is not entirely true.
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Another common red herring is the argument that somehow a computer forces one to race up to a safety stop. Computers DON'T set your profile. While there are some minor problems, such as some computers wanting to see 3 minutes of hang under 20', in general you should be able to dive any profile you want, and if it is a proper one, then the computer will be happy. Computers most definitely do NOT interfere with doing deep stops.
IMO, smart computer use includes doing a proper ascent and stops.
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As to the original topic of this thread, I look at computers as a useful tool. I pretty much know how much air I have at any given time, and know what my SPG should read when I look at it. I don't throw it away though. Another analogy would be that I both rely upon my senses and upon a speedometer when driving.
My attitude towards a computer is similar. I have a pretty good idea of what I'll see when I look at it, but I don't throw it away.
One can argue whether your brain should be the primary decompression tracker, with a computer as a backup; or whether my method of using the computer to track decompression status and using my brain as a general validity check is optimum. But in either case, using both is better than just relying solely on either the computer, or solely upon one's ability to track depth and time.
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As I said in an earlier post, there are some situations where computers don't add much value (square profile dives, shallow dives, dives with significant deco where prior gas planning and adherence to the plan is important). They are very useful tools, however, in many diving situations --- most signficantly multilevel, repetitive dives without signficant decompression obligation.