I don't know to whom you are responding with this question. I scrolled back through the thread and realized it may have been me. If so, I was not very clear. An AOW deep dive has to be at least 60 feet deep. I do know that there are some shops that will weezle that depth using tables and altitude adjustments. Here is how it could be done where I live in the Denver area (5280 feet). Follow these steps closely to see how it works.I get how you can simulate deco by using nitrox and setting computers to air but how do you effectively simulate depth by substituting tables?
"OK Billy, I realize the pool is only 12ft. deep but we're gonna be pretending that it's 120ft..." Do you use 19cu ft tanks to simulate gas consumption?
Some things can't be faked that easily.
- The diver goes to 41 feet for 30 minutes at Aurora Reservoir, just outside Denver (5280 feet elevation).
- Using tables, that is rounded up to 50 feet.
- To adjust for altitude, use a Theoretical depth at Altitude table.
- Go to the 50 foot row and move across to Denver's altitude (5,280 feet), which is rounded up to 6,000 feet.
- The value there is 62 feet, so PRESTO!, that 41 foot dive is now a 62 foot dive and valid for AOW.
- But wait! There's more! Theoretical depth is used for planning decompression for dives; i.e., finding your pressure groups. That means that 62 foot theoretical depth is rounded up to 70 feet when you log your dives if you are using tables. That means our AOW student will log that 41 foot dive as a 70 foot dive.
That 6 step process shows the absurdity of using tables at altitude like that, because what I showed is indeed what you would do to calculate pressure groups for decompression.
- Let's say that the 41 minute dive went for 30 minutes.Using the process described above, the student would be in pressure group O--pretty serious nitrogen loading. If the dive to 41 feet were repeated after a 45 minute surface interval, that calculated nitrogen loading would limit the student to a 22 minute dive.
- If the student had only gone to 40 feet, there would have been no rounding up originally, and the theoretical depth would have been 50 feet--again no need to round. The students would be in pressure group I. If the dive to 40 feet were repeated after a 45 minute surface interval, that calculated nitrogen loading would limit the student to a 63 minute dive.