Posted by Kendall Raine on May 09, 2002 at 08:41:55:
In Reply to: Re: PADI dive table posted by Tallguy on May 08, 2002 at 09:10:20:
It depends on what you mean by "reliable" and how you use the tables.
The tables are simplest to use in a square profile. With a square profile a table will yield the same NDL or deco times as a computer running the same model. Hence, the table and the computer will have the same "reliability."
For multi level dives, the table is really more conservative unless you depth average. That's one big reason for the popularity of computers:they give you more "bottom time" because they depth average. If you use a table and depth average well, you should end up with roughly the same schedule as a computer running the same model. That's true whether you are talking about one dive or multiple dives.
The real issue of unrealiability comes in with the quality of the model to account for residual inert gas loading and unloading. This is true regardless of whether you're using a table or a computer. The error terms inherent in the model compound over multiple dives. Since the computer is depth averaging, those errors compound faster then if you're using a table without depth averaging. Again, if you depth average, your table schedule should closely match your computer schedule. The unreliability then comes with the model, not the form of the model.