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Barrie Kovish wrote,
> Last summer I performed an experiment which relates to the issue
of
> free diving and the bends.  I carried an old SOS decompression 
> meter along on a free diving trip.
.......
> the total time underwater but it was probably in excess of 1 hour.

> Anyway when I turned the dive and started swimming to shore the 
> decompression meter showed a significant amount of nitrogen
> absorption.  If the meter was linear then with a somewhat 
> longer/more aggressive dive profile I would easily have entered
the 
> decompression zone.

Surely the decompression meter is *assuming* that you are 
absorbing nitrogen from the air in your lungs which is at ambient
pressure?  Which, on a free dive, it isn't.  A breath of air taken
at the surface and held on a free dive to 30m doesn't result in your
lungs compressing to one quarter of their size!  The musculature of
the body resists the thoracic squeeze.  Think about what would 
happen to Pippin free diving to over 100m?


I think we should consider why a free diver should get bent at all? 
It seems to me that the rapid number of ascents plays a very
important part.  Could it be the formation of micro bubbles from the
early ascents that are transported around the body on subsequent
dives?  I am not trained in physiology but it looks to me that the
recent case was due to a number of micro bubbles 'amalgamating'
together at some form of restriction?  Any ideas?


Ken Gould

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