@DAN Southern Africa In respect of the pool dives (the first experiment described by Sandro), comparing a dive with GF (approx) 100:100 to one with GF approx
50:100 and then claiming that deep stops are better because
50:100 was better than 100:100 completely misses the point that technical divers are interested in. No one is saying that 100:100 is a good idea! The real question is "how deep should your deepest stop be"? and in the technical diving world, that translates into "should they be as deep as prescribed by bubble models, or are those stops too deep"? The studies of single "deep stops" in no-decompression diving mentioned in the presentation are completely irrelevant to this question. For decompression diving, all the published evidence to date suggests that bubble models prescribe deep stops that are too deep for optimal decompression. This is supported by Sandro's second experiment (the NDAC one) comparing 20/85 (very like a bubble model in terms of deep stops) with 50/75. Bubbling after the deeper stop dive is more sustained, and likely more problematic as he points out. Parenthetically, the dives in both studies were not really deep enough to fully unmask the potential disadvantages of over-emphasizing deep stops. In summary, I would characterize this body of work by saying that the first experiment demonstrates that extremely shallow stops (eg GF Lo 100) are not a good idea (but no one was claiming that), and the second experiment supports other work in suggesting that over-emphasizing deep stops to the extent seen in bubble models is also not a good idea. For some time now a number of us have been suggesting that for the typical depths of deep technical decompression dives (50 - 100m) a sweet spot probably sits somewhere near a GF Lo of 50.