On Tuesday, January 15, 2002 12:38 PM, Dennis Darragh wrote:

> wow ----- get real people , i've been following this thread and can you
> really even think bout teaching the decompression theory without the
> tables ,

Mate!  I'll have a crack at playing Devil's Advocate!  :-)  (With the
understanding that - for want of a better standardised system that *all*
divers have hitherto been encouraged to learn - teaching the use of tables
still has relevance.)  :-)

First define, "the decompression theory"?  In its simplest form I guess it
can best be described as dealing with gas absorption by the tissues and
organs of the body when breathing higher than normal partial pressures of
various gases and the subsequent return to normal pressure?  Apart from a
general agreement that this does happen, there seems to be no consensus on
the exact mechanics of the process.  That being the case, what we teach - as
far as decompression theory is concerned - centres, in the main, on popular
theoretical models.

In that regard, the tables are nothing more than *reasonably* accurate
prediction tools peculiar to each of those models.  While they're a guide to
inert gas loading they do little or nothing to explain decompression theory
or the differences between 'fast' and 'slow' tissues.  Neither do they take
into consideration the fact that very few recreational divers perform square
profile dives.  Nevertheless, as a safety tool, knowing how to use the
tables - even if there's no understanding - is better than not knowing how
to use them.  :-)

Having said that, all that the tables are, (it seems to me), is a primitive
form of computer.  Knowing how to apply them doesn't bestow any better
understanding of decompression theory than the user of a computer who
acknowledges the roles of depth and time in the risk factors associated with
diving.

 what reference would be used ???????????????? i would love to
> hear this one!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

As a learning tool, computer simulations that plot the dive and
simultaneously display the loading and off-loading for a variety of selected
tissues - regardless of the model - is a much more graphic way to
demonstrate the effects of pressure on the body than by trying to visualise
those same effects through *only* teaching the use of manually computed
tables! :-)

Rather than an 'either/or' approach to tables versus computers - in which
divers either ignore the past or refuse to confront the future - it does
seem to me that the Training Agencies need to re-assess the whole approach
to - and expand on - the way that decompression theory is taught.   :-)

And until such time as researchers come up with some firm conclusions about
decompression safety, most of us will still be obliged to rely on what
others tell us is safe and good!  :-)

Strike