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Where When How May/June 2017 : Page 98

Southern Stingray -see story page 103. Photo by Mickey Gopigian of Flamingo Divers. Findings and Conclusion of the Smithsonian Institution, Reverse Dive Profiles Workshop, Washington, D.C., October 29-30, 1999 Findings : Historically, neither the U.S. Navy nor the commercial sector have prohibited reverse dive profiles. Reverse dive profiles are being performed in recreational, scientific, com-mercial and military diving. The prohibition of reverse dive profiles by recreational training organizations cannot be traced to any definite diving experience that indicates an increased risk of decompression sickness (DCS). No convincing evidence was presented that reverse dive profiles within the no-decompression limits lead to a measurable increase in the risk of DCS. Conclusion : We find no reason for the diving communities to prohibit reverse dive pro-files for no-decompression dives less than 40 meters sea water (130 fsw) and depth differentials less than 12 meters sea water (40 fsw). searcher named Dennis Walder in 1968. His rationale was that by making the deeper dive first, one might crush “silent bubbles” — assumed progenitors of de-compression illness — making the devel-opment of bends less likely on that and subsequent repetitive dives. But this was based primarily on theory and informed speculation, not empirical evidence. Moreover, no reference to any deep-first guideline appeared in any recreational diving literature until 1972, when the fol-lowing statement was published in PADI’s Basic Scuba Course Manual (a curriculum segment of the then-current PADI Instructor Manual): “One very im-portant rule—WE ALWAYS MAKE OUR DEEPEST DIVE FIRST when using the dive tables.” No rationale was provided, though examples were often included during training showing the aforemen-tioned advantage of avoiding decom-pression stops. Other sources picked up on the deep-first issue, such as Dr. Chris Dueker. In his 1978 publication, Scuba Diving Safety — a book that received wide dis-tribution within the recreational diving community — he recommended the deep-first guideline. Dueker was also one of the few to provide any rationale for the recommendation, when he wrote, “Generally it saves time to take the deeper of the two dives first.” Once again, his suggestion was based on prag-matism, not decompression safety con-cerns. In 1979, a symposium entitled “De-compression in Depth” was sponsored by PADI and brought together many of the leading experts in recreational diving safety. Interestingly, that program in-cluded no discussion of the deep-first issue. However, all example problems contained in the symposium proceed-ings followed the rule, except for one re-verse profile, which was labeled a “contingency.” This was a clear implica-tion that reverse profile dives were not to be planned. 98 • • • • • MAY/JUNE 2017 “Where When How -Turks & Caicos Islands”

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