John, let me throw in one more thing. There is a big difference in going deep in the Caribbean and in the quarry at Hopkinsville. The quarry is MUCH more challenging at any given depth than the Caribbean sea due to lack of visibility and water temp.
A 70' dive in warm water with 100' visibility isn't a real risky dive. In the quarry, the temp at 70' will be in the low 40's year round. It's a different beast.
As mentioned, all anyone can do, including the training agencies, is make recommendations.
While I agree with most you have stated, Bob, I will disagree with your statement about a 70' dive in warm water with 100' vis not being very risky. There are times it can be. It all depends on the local conditions. If you do that dive in a very swift current, down currents or even multiple shifting currents, & you as a diver, are not prepared for it, it can be VERY risky. When I was in Sipadan Malaysia, last year, we encountered some fairly strong currents on our dives. It took me about 2-3 days of diving it to fully adjust. During that time, my air consumption was nothing like it normally is (it sucked, big time
). It took me that time to learn to use the current to my advantage, relax, instead of fighting it. Having mostly dove the same quarry & the Caribbean, my exposure to strong currents was extremely limited. Now, one advantage I did have was general experience. I knew when to call a dive because it was too much for me. That is the reason, a diver, with training, mentoring or in very tiny increments, should expose themselves to as many different diving situations as possible. Know SULLIVAN2049, that there is no bad reason to call a dive, & do not be ashamed to end it, if a dive is not going well for you. It is any diver's prerogative to be able to end any dive at any time, for any reason, with no risk of ridicule. If your buddy gives you a hard time about aborting a dive, then they are no buddy that you really want to dive with. Some situations require or highly recommend add'l training before attempting. I will be interning to teach deep diving at the quarry this summer, as Bob mentioned it is a very different environment. The vis usually isn't too bad, in fact it's usually clearer, deep on the bottom than in the shallows (not so many people stirring it up), however it IS cold. Hope to see you at the quarry this summer & get a chance to dive with you..