On Wednesday, March 21, 2001 12:47 PM, J.M. Vitoux wrote:

(snip)
> Originally I thought that a reverse profile referred to a dive
> during which the deepest part is reached late during the dive
> (for example 20 minutes at 10m then go down for 5 minutes at 30m
> before ascent). From the usage I see here and there, this does
> not seem the case. So how would you call such a dive profile.
> Inverted profile?

That's a good question - and one that I can only answer from my perspective!
:-)

I was taught to plan my dives and go to the deepest planned depth at the
beginning of the dive and then - on a swimming dive - to move progressively
shallower avoiding, as far as possible, any sort of saw-tooth profile!
(Your 'inverted profile'?).  This was because - in a pre-computer age - the
dive was based on a square profile model in which bottom time was taken to
begin from leaving the surface until final direct ascent to the surface, and
depth computed as the deepest point reached during the dive.  In the
instance you quoted that would be logged as a 30-metre dive for 25 minutes!
(It could be claimed to be badly executed, but it would still be classed as
a single dive to the maximum depth of 30-metres!)  :-)

To put that further into perspective, if one dive was conducted to a maximum
depth of 30-metres for 25 minutes before the diver ascended, and he then
undertook a second dive within the space of ten minutes to 40-metres for 20
minutes, then it would be classed as one dive to a max. depth of 40-metres
for 45 minutes.

A subsequent dive within a given time-frame and where the maximum depth
achieved was greater than 40-metres, would be classed as a "reverse
profile"!  :-)

Given the number of new decompression theory models that now abound - and a
greater understanding of the topic - it might be a moot point!  But that's
my understanding of the term!  :-)

Strike