Quote Originally Posted by jj1987 View Post
That seems a lot more reasonable than saying 60ft limit in my opinion and from my observation....I've yet to hear what dangers are present at 80ft that are not present at 60ft. I still kind of find it funny that 130ft is the safe recreational limit on air (ppo2 of 1.037), and their safe limit on ean36 is 94ft (ppo2 of 1.39). I'll admit to being a n00b with this stuff, but it seems random to say the least. Overhead training limits make sense to me, but OW have always left me wondering "why". If an instructor could fill us in, I'd be interested to hear the explanation.
there are 20 feet worth of more danger. if no feet is 1 unit of danger, then 33 is 2 units of danger, 66 is 3 units of danger, 99 is 4 units of danger. Danger multiples with depth, it changes nature too, but just the fact that depth = pressure = danger should be enough to clue you in.

ppo2 is not the only consideration. it is not random. don't do the dives if they make you wonder why.

-skip