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To: techdiver@opal.com (Internet @ Oz-Email {techdiver@opal.com})
To: maiser@co*.ci*.uf*.ed* (Cave Diver Server)
To: hypbar-l%technion.bitne.t@ta*.ta*.ac*.il* (HyperBaric & Diving Medicine List)
Subject: Recreational Mixed Gas Diving in Australasia
From: ROB CASON <iantdaus@oz*.co*.au*>
Organization: OzEmail Pty Ltd
Date: Sat, 29 Apr 95 10:50:05 +1000
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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