Reg, you keep injecting rational thought into what otherwise could become a fairly good brawl . . . 

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The DiveRite NitekHE does all the calculations for you, if you are planning to switch gasses.
So does the VR3.
You simply only need to input the gasses you are using correctly, and switch underwater appropropriately, and tell your computer what you have done, and then it gives you your next stop depth and stop time.
And V-Planner will have done the same in advance for the dive plan and gas planning. The V-Planner output also provides on-the-fly backups that you can memorize as well, or you can put it onto tech forearm-slates as a backup to your dive computer.
There is simply no need to do any calculations yourself in the 21st Century.
Unless you really want to, yourself, the hard way, either with a pencil and calculator or else with an M/S Excel spreadsheet.![]()
A ScubaBoard Staff Message...
Gotta love it.
Lessee, here...
OP asks a question in post #1
Question answered in post #2
OP says "Thanks" in post #3
Water muddied in post #4
Bomb thrown in post #5
followed by some 50 tangential posts headed in about half a dozen different directions, including the obligatory PADI bashing and GUE evangelism.
Gotta love it.
Good idea.It may consist of his ordering everyone out of the water, NOW.