printable copy of dive tables?

[boulderjohn]

Long time ScubaBoard members will remember a forum called As Dr. Deco (Or something like that). If you asked a question about decompression theory, Dr. Deco would answer it. Dr. Deco was Dr. Michael Powell, one of the researchers who developed the PADI tables. He was a NASA scientist studying high altitude decompression.

 

[boulderjohn]

As long as we are actively discussing tables again, I want to admit an error in thinking about tables I have repeated many times on ScubaBoard. Whenever people would say they keep a copy of the tables on hand in case their computer goes bad, I would reply that they usually could not do that, because they would have done a multi-level dive that gave a bottom time far in excess of the maximum bottom time for the tables. For example, I have exceeded 90 minutes on dives deeper than 100 feet and stayed within NDLs. I believe I wrote about that earlier in this thread.

I was wrong.

What I did not account for is something rarely mentioned about NDLs. (Ironically, I think the person who has mentioned it the most on ScubaBoard may be me.) Multi-level dives are possible because once you leave your maximum depth, it does not seem to matter how long it takes you to reach the surface, as long as you don't lollygag so long you go into deco on the way. Therefore, if you left the bottom within NDLs and took 80 minutes to get to the surface, with most of that at shallow depths, if your computer went out between dives, you could indeed use maximum depth and the time you left the bottom for a table-guided dive.

 

[tursiops]

 

[tursiops]

What I did not account for is something rarely mentioned about NDLs. (Ironically, I think the person who has mentioned it the most on ScubaBoard may be me.) Multi-level dives are possible because once you leave your maximum depth, it does not seem to matter how long it takes you to reach the surface, as long as you don't lollygag so long you go into deco on the way. Therefore, if you left the bottom within NDLs and took 80 minutes to get to the surface, with most of that at shallow depths, if your computer went out between dives, you could indeed use maximum depth and the time you left the bottom for a table-guided dive.

I do not think this is correct. The use of tables this way does not give you enough Nitrogen uptake to allow the valid planning of the next dive. For example (using the PADI eRDPml) a 130 ft air dive has a 10 min NDL. If I leave the bottom at 9 minutes and surface, my end-of-dive pressure group is H. But If I spend 10 minutes at 80 ft and 60 minutess are 40 ft, my ending pressure group is X. I shoujld plan the next dive with X residual, but if I use the RDP as you describe I would only use H residual....

 

[boulderjohn]

I do not think this is correct. The use of tables this way does not give you enough Nitrogen uptake to allow the valid planning of the next dive. For example (using the PADI eRDPml) a 130 ft air dive has a 10 min NDL. If I leave the bottom at 9 minutes and surface, my end-of-dive pressure group is H. But If I spend 10 minutes at 80 ft and 60 minutess are 40 ft, my ending pressure group is X. I shoujld plan the next dive with X residual, but if I use the RDP as you describe I would only use H residual....

I am not familiar with the way you are using the table.

 

[inquis]

I do not think this is correct.

True, the "ascend no faster than 30 fpm" guidance doesn't equate to a multi-level dive. I'm sure there are some profiles for which it works, but not in general.

 

[tursiops]

I am not familiar with the way you are using the table.

I am not using the table. I am using PADI's calculator version -- the eRDPml -- which allows multi-level dives and 5-ft depth increments. It is a digital calculator version of The Wheel. You can access it at .::Electronic Recreational Dive Planner - eRDPML::.

 

[boulderjohn]

I am not using the table. I am using PADI's calculator version -- the eRDPml -- which allows multi-level dives and 5-ft depth increments. It is a digital calculator version of The Wheel. You can access it at .::Electronic Recreational Dive Planner - eRDPML::.

OK--but that is different from a plain table.

 

[tursiops]

OK--but that is different from a plain table.

Maybe my point was not clear. You argued that you could use a "plain" table in case your computer went out, by just using your BT and ignoring all the time spent surfacing. No?
My point is you are still on-gassing during all that additional multi-level diving, and that changes your nitrogen uptake so you cannot calculate what the NDL is for a successive dive.
I used the eRDPml to prove my point.

 

[boulderjohn]

I understand. What it comes down to is that I was more right with my original belief than with my change of mind. Unless you do a pretty much direct ascent on your computer dive, you cannot use a table for a follow-up dive because you won't know your pressure group.