Multi level dives

[Wibble]

Sorry, my phone doesn't work at 40m and I'm not always able to stick exactly to the minute on a preplanned dive profile. Besides, what else you have to do while in deco stop other than to pull out your tables and do some math?

Which, of course, is why you have two or three Shearwater computers to tell you how much deco you’ll do… Obviously you can change that if you feel you want to be more conservative or aggressive. The main thing is the Shearwater computers track your depth and gasses breathed. Those table things only know one level so will be more conservative if used correctly.

For some reason a few people — nowadays very few people — still like to risk doing Ratio Decompression on the fly. Hope they all have good memories of their profile depths to base the deco obligation upon.

 

[Blackcrusader]

Older Sherwood regulator (dry bleed)?

Nah Apex regulator

 

[crofrog]

depth averaging

 

[Celt]

I post this in the new diver forum but I think that the answer should come from experienced divers and probably those interested in science.
The diving tables tell you what the NDL is. I know that they should only be used for U shape dive profiles bit some use them for multilevel dives.
Let’s say that your NDL at 40 meters is 5 minutes and is 10 minutes at 30 meters. Some people believe that you can stay 4 minutes at 40 meters and then go to 30 meters as if the previous part of the dive with the on-gassing did not exist. Is it right?
Of course, we have DC today but some people still use tables for such dives.

Why bother, just plan it to 40m. Use your time shallower as built in safety.