Re: Isn't that what the watches with the numbered bezels are for?
Those bezels are a hangover from old school I think. Before dive comps and so on, when you worked out your dive plan and profile by hand and lookup tables, wrote it on a slate and that was basically your stopwatch.
Rotating the bezel meant you could align it with where the hand was currently
A Dive computer basically does all of the above, plus more, (depending on the model).