Max. depth, average depth, computers & tables

[JeffG]

Did anybody notice this thread is four years old?

Yep

(Cause I know its not the truth, my wife tells me so)

 

[Charlie99]

For general dive planning purposes only, if I use the tables to estimate a multiprofile dive by working through them using zero surface interval and ascent time rolled into the deeper depth time, will I get a rough idea of what my computer is going to allow or am I wasting my time?

Short answer: That's a good method for dive planning purposes, but the dives might go slightly into deco.

I haven't verified it for tables other than the PADI RDP, but the result will be correct for the compartment on which the Pressure Groups or Repetitive Dive Groups are based upon, which is the 60 minute compartment on the PADI RDP and wheel. But you can find combinations still within limits of the table using the 0 min SI method you describe, but which slightly exceed the limits for the faster compartments.

In other words, it's good for rough planning of a dive, but the results are sometimes slightly into deco per the model the table is based upon.

-----------------------

The PADI wheel is very similar to the PADI RDP, but has slightly reduced NDL limits to keep all valid combinations within NDL. The wheel also has some restrictions on what depth levels are acceptable to combine.

I converted these limits back into something similar to a PADI RDP.
http://www.scubaboard.com/gallery/showphoto.php/photo/3142/ppuser/1596
(click on the photo to get a bigger version to print).

In practice, I just do as you proposed and use the backside of the RDP and treat a proposed dive as a string of dives with 0 SI. The "Flat Table" linked to above has 5' depth increments and let me directly compare the table method and what the wheel generates, but on a practical basis the 10' increments of the PADI RDP are sufficient.

 

[boat sju]

Thanks Charlie. That flattened wheel table should give me something to obsess over for several days. I like your disclaimer about not using it if you don't understand it. I was curious if there weren't restrictions on depth level combinations like that, but couldn't explain my concerns to the guys at the dive shop. I want to take a class so I understand multi-level diving better but I'm not sure which one. I don't think they teach the wheel in the SSI deep diving classes here and I got the impression that the computer class doesn't amount to much. Maybe I'll take a Nitrox class and just ask a bunch of questions.