Bowzer:
As I suspected, there doesn't seem to be a standard answer. NAUI's 1 min at 1/2 the max depth and deduct it from the 20 foot stop, DUI has lots of stops
dive to 100 feet
depth * NAUI * DIR
50 * 1 * 1-2
40 * - * 1
30 * - * 1
20 * 3(2) * 3
10 * - * 3
total * 4(3) * 9-10
It would be nice to follow this and see what shakes out in the future. DAN has published a study but I am not sure how it relates to recreational diving. I don't recall seeing recommendations specific to and usable directly by recreational divers.
If there is indeed a Dr. Decompression, perhaps she will weigh in?
bty, can anyonr tell me how to preserve formatting , the <pre> tag doesn't seem to work here.
I suspect that you are ready to buy your own copy of V-Planner (not expensive, only around $100 cheap!) and play with it yourself.
You will see that most dives to not require a deep stop. A deep stop is normally 1/2 the depth of your MOD (max depth) of your dive.
If you plug the deep stop into your dive profile on V-Planner, you will see that it makes no difference to your NDL dive. You will also see that the safety stop is completely optional as well, for any given single dive.
But once you start adding on several repetitive dives to the V-Planner dive plan, then under certain circumstances you will end up with a required stop.
There is no really hard and fast rule. Each different combination of repetitive dives results in different requirements.
Having said all that, I myself always do a 1 minute deep stop at 1/2 of my MOD. Then my next 1 min stop is at 1/2 the distance to the surface. And finally, my 3 min stop is at 15 fsw. Even though V-Planner says that in most cases these stops are purely optional, even with the most conservative features selected with the software. This gives me 5 mins of decompression on every NDL dive. (The modern in-vogue word is off-gassing.)
And yes, there is really a Dr Deco. He is a Ph.D. A genius of sorts, whose math and theory is really hard to follow. I hope you catch his attention, because I will enjoy reading his fascinating reply.