Marv writes:
> To all on the list, have you ever dove with anyone who could
> get over an hour on a single 80 cuft tank at ~ 60 ft, go into
> deco and with enough air for both the 5 min deco stop and a
> 5 min safety stop at ~ 10 ft and still have air in her/his tank?

And retain a 500psi reserve, of course.  This means 65ft^3 of air available.
Running a quick spreadsheet where I can vary the SAC and driving the bottom
time to 60 minutes, I come up with this:

Estimated       Available         Planned         Air used by   Air used by
Net air Time at
SAC             Vol (ft^3)  Depth(ft)   5 min @ 15'   5 min @ 10'
available       planned depth
0.375            65               60        0.545         0.4886
63.966      60.527

So you need a SAC < .375 to do this plan.  BTW, note that ascent/descent
times are ignored, so they must be assumed to be included as part of the
60minute square profile to 60fsw (which conforms with the procedures for
some dive tables, but not the old USN's).

In running some different values through the same spreadsheet, I get (same

SAC     Time at 60fsw

0.3     75.90
0.4     56.68
0.5     45.15
0.6     37.46
0.7     31.97
0.8     27.85
0.9     24.65
1.0     22.09
1.1     19.99
1.2     18.24
1.3     16.76
1.4     15.50
1.5     14.40

Now on a good day, my SAC has been as low as 0.4, but my average depth was a
SWAG, so I don't really trust it yet.  I used to be around .7 as I'm still
not sure why it suddenly dropped like it did a couple of years ago.  It
doesn't help that I don't really have many truly square (and thus easy to
calculate) profiles.