Dive Table Question

[sam1]

I note that the NDL for the PADI and NAUI tables for the first dive in the example above (60 feet) are the same: 55 minutes. The difference noted shows up in the second dive. I really don't know the NAUI tables, but Thalassamania (above) notes that the NAUI tables are based on the U.S. Navy tables. PADI's Encyclopedia of Recreational Diving (p. 5-62) says that the surface interval credit in the Navy tables assumes that the 2-hour compartment controls the repetitive dive. The PADI tables assume it's the 60-minute compartment that does (so any given surface interval reduces your residual nitrogen in the controlling compartment by more in the PADI tables than in the NAUI tables, thus longer NDL for repetitive dives).

 

[Thalassamania]

You've got it, good explanation.

 

[sayuncle]

I'm new to diving and have quite an appetite for information. I am a NAUI OW diver with less than 50 dives under my belt. I learned dive planning with the NAUI RGBM table and though they are very simple to use they leave me feeling like there is more to it. Obviously there is sooooo much more to it, but they seem to be over simplified compared to tables I've seen some of my dive buddies using. I know nothing of group letters and the like.

Thalassamania, is it likely that I will encounter these more complicated (and maybe less mysterious) tables as I continue through my formal dive training or is this informaion that I'll need to seek on my own?

 

[aquaregia]

[-]The NAUI tables should give you letter groups.[/-]

Edit: Never mind, was looking at the wrong tables
Are your friends using this: http://www.scubadiverinfo.com/images/Dive_tables_NAUI.jpg ?

 

[diver 85]

Get a computer.

+1 here.......

 

[knowone]

The essentials of DEEPER sport DIVING. John Lippman. for reading
or
Find some ABYSS software somewhere. for computing

 

[JohnE]

As was said, the navy tables assume deeper nitrogen saturation due to deco diving. The padi rdp tables assume you will be less saturated in the harder to offgas tissues since it is no deco oriented as most rec diving is. So, the rdp gives you about twice the credit for surface intervals.

Your results hold for that, 25 minutes and 49 mins.

When you get a computer youll find some differences from the padi RDP tables. Suunto uses the RGBM reduced gradient bubble model (see RGBM ).

So, yes, you will encounter the various models and you will need to choose the one that applies best for you and your diving. Or, just buy a computer and do what it says without knowing why. I did that for a while like many do.

A divemaster or instructor can help you with this.

 

[waterpirate]

For the table curious there is no substitute for god reading and a dry computer based software. I had several puck failures that led me to a bottom timer. That move led me to the software, I settled on v-planner. By adjusting the user settings and running many couch dives you get a really good idea of how it all works. When I went deeper it was easy to just keep cutting tables.
Eric

 

[Mr Carcharodon]

Lippmann and Mitchell's "Deeper into Diving" has the best discussion out there of various different tables (DAN is the publisher and best source for this book). Although not in enough detail to see exactly how they were arrived at. For an example of that take a look at Workman's 1965 paper which you can get at Rubicon Research http://archive.rubicon-foundation.org/dspace/handle/123456789/3367 .

 

[sayuncle]

[-]The NAUI tables should give you letter groups.[/-]

Edit: Never mind, was looking at the wrong tables
Are your friends using this:

I've seen that table around, but the one my buddy uses (or used rather) is a PADI table from way back. After we discussed them we opted to use the NAUI RGBM due to it's simplicity. We were quarry diving to practice some nav and, well just to dive cause diving in a quarry is better than not diving