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Reply to message text: As many of you are probably aware, recreational mixed gas diving in Australia / New Zealand has encountered considerable opposition from the Queensland & New South Wales Governments and the Royal Australian Navy (RAN). Much of the opposition was based on professional advice received from the RAN Diving School, HMAS PENGUIN (HMAS PENGUIN letter 88/1/2 (DS 321/91) dated 26 September 1991) The following are extracts from that HMAS PENGUIN letter. I let you all be the judge as to the professionalism of the advice provided by the RAN Diving School. "The FGG 111 set itself is very heavy and when combined with the extra three to six cylinders, will make the diver extremely negatively buoyant and very cumbersome. The wetsuit and buoyany compensator will lose effectiveness between 20-50 metres and cause the diver to plummet towards the bottom. This will cause the changes in breathing gas to become hurried and possibly too late or incorrect. This will result in hypoxia or Cerebral Oxygen Toxicity and subsequent drowning. If the diver succeeds in making it to the bottom conscious, he will be unable to swim up off the bottom due to the extreme negative buoyancy caused by the weight and dimensions of the equipment. He will then have to climb up a shot rope (if one is provided) which will be very slow and tiring. Endurance will be reduced dramatically causing a change in gas at a deeper depth than intended, also resulting in Cerebral Oxygen Toxicity" The buoyancy calculations for this allegedly proposed dive were made by a LEUT M.B. McIntyre RAN, a Miine Warfare and Clearance Diving Officer Under Training who had just completed the Clearance Diving Phase of his course. This information is contained in his report to the Officer-in-Charge RAN Diving School dated 03 October 1991. "Diver Buoyancy: FGG 111 - approx (-) 39 kg 6 staging cylinders (88 cu ft) - approx (-) 86 kg Lead Weight belt - approx (-) 9 kg Buoyancy compensator - approx (+) 15 kg Wetsuit - 0 at depth --------------------------------- negative 119 kg buoyancy" The Commonwealth and Defence Force Ombudsman (Commonwealth and Defence Force Ombudsman letter C/94/11770 dated 19 October 1994 to the Assistant Chief of Defence Force (Personnel) asked several questions including the following: "Was Lieutenant McInyte qualified to make judgements on the dangers of mixed gas diving? Was he an experienced diver? There is a reference to his having completed a Navy course, which suggests he may not have been particularly knowledgeable at that time. Was it appropriate that he brief Workcover (NSW WorkCover Authority) on 30 September about the percieved dangers of mixed gas diving?" "If it was someone other than Lieutenant McIntyre who made the judgement on Navy's behalf concerning the dangers of mixed gas diving, who was that person and what experience or knowledge did he/she have to enable that judgement to be made?" The following replies to the above questions were made in a letter signed personally by the Flag Officer Naval Training Command, RADM P.D. Briggs RAN (Naval Training Command Minute NTC02/186.1 - NTC2830/94 dated 16 November 1994. "When McIntyre attended the seminar he had completed and passed the Diving Phase of the Clearance Diving Officers Course. This is a comprehensive and demanding profesisonal course and he was therefore fully conversant with and had experience in RAN procedures for mixed gas diving........ The information he gathered (not his opinion) was the basis for much of Navy's concerns at the time ...... Reference to LEUT McIntyre briefing Workcover on 30 September 1991 is not held; however, it would be not inappropriate for him to have briefed them, after he had held discussions with the Diving School and School of Underwater Medicine." "No one person made 'the judgement on Navy's behalf concerning the dangers of mixed gas diving'. Navy's concerns was based on the combined experiences of the staff at both the Diving School and the School of Underwater Medicine (SUM). The complement of the Diving School at the time was 2 Lieutenant Commanders, 1 Lieutenant, 1 Warrant Officer, 3 Chief Petty Officers and 6 Petty Officers. As a very conversative estimate this would represent some 185 years of mixed gas diving, using RAN procedures." As McIntyre's buoyancy calculations have not been disputed by the RAN Diving School and the RAN School of Underwater Medicine, it would appear that both these RAN Schools did not appreciate the difference between the weight in air of diving equipment and its buoyancy in water. Furthermore, they apparently did not comprehend the buoyancy characteristics of the Drager FGG / FGT. The Drager FGT has been in service in the RAN as the primary mixed gas breathing equipment since the early 1970s when it replaced the CDBA. If you are interested in reading more about this incredible saga, please let me know. This is just a very small sample of the copius documentation on the issue. As this message is based entirely on official documents from the RAN and the Commonwealth and Defence Force Ombudsman, please feel free to echo it to anyone you think may be interested.
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