Posted by TDI_2 on May 21, 2002 at 11:29:07:
In Reply to: Matching the profile posted by h on May 21, 2002 at 10:08:05:
IF youre going to try to "match the profile," remember that your "bottom time" ends the moment you begin your final ascent, and does not include your ascent time nor your 15 fsw safety stop time.
And if your ascent was along an enclined beach on a long egression, then it does not technically include the time you spent swimming back to shore underwater as you become shallower and shallower.
So your dive computer will need to give you some sort of profile data so that you can look and see at what point in your dive you began your final ascent, allowing you to calculate your actual "bottom time" versus the readout of your total dive time on your computer.
Dive tables were designed with "square profiles" in mind. So that complicates things, when you try to go back and forth between a diving computer and dive tables, or when you try to "match the profile."
The bottom line is still this: no tables are perfect, no diving computer is perfect. Youre still pretty much on your own, and so you need to use a diving computer and/or dive tables conservatively to be safe.
It becomes more pronounced of an issue when (1) youre at a resort diving for several days in a row and/or (2) you dive deep.
Stay shallow [above 50 fsw], stay well within NDL, and dont dive more than 2 or 3 dives a day, for each day of an ordinary diving weekend, and you should be fine as far as DCS risk is concerned. But there are no absolute truisms in scuba diving.
The whole purpose of a diving computer and/or tables is to avoid DCS.
God did not tell Moses on the two tables that everyone had to incribe their diving data into their logbooks a certain way whether or not diving with a computer.