Dorky Nitrox Question

[TMHeimer]

You plan 2 dives using the PADI special 36% and 32% tables. After the first dive (36%) and SI you arrive at your pressure group to start the 2nd dive (32%). To find your RNT to plan the 2nd dive you use the flip side (table 3) of which of the 2 tables?

 

[RJP]

You plan 2 dives using the PADI special 36% and 32% tables. After the first dive (36%) and SI you arrive at your pressure group to start the 2nd dive (32%). To find your RNT to plan the 2nd dive you use the flip side (table 3) of which of the 2 tables?

Think about it this way...

The residual nitrogen is residual from the last dive you did. Which gas/table did you do THAT dive with? Now which gas/table are you going to do your NEXT dive with?

 

[Walter]

First dive on EAN 36 is conducted using EAN 36 tables. After the surface interval, you take that letter group designation and switch to the EAN 32 tables to get your RNT for the second dive using EAN 32. The residual nitrogen is nitrogen already in your body before you start the dive on EAN 32. It is as if you've already dived at your planed depth for the residual nitrogen time on your next mix.

One note of caution, while you do switch tables, you must stay with the same type table. If you start with the PADI EAN 36 RDP, you switch to the PADI EAN 32 RDP. You must not switch to the US Navy tables, the SEI tables or any other table. Of course, the same applies if you start with the US Navy tables (or any other), stay with the US Navy tables (or which ever you started with). An A on one is not an A on another.

 

[HowardE]

Think about it this way...

The residual nitrogen is residual from the last dive you did. Which gas/table did you do THAT dive with?

This isn't correct.

If you dive with 36% then plan a repet dive with 32% (although most agencies recommend diving the leanest mix first - since most recommend doing the deepest dive first)

The RNT would be calculated on the Mix you're GOING to use.

IOW: Calculate your ending pressure group on the 36% table. Calculate the SI Time, and ending pressure group (offgassing rates are the same for either table)

Then take the table for the mix you're GOING to use. And look on the flip side (table 3) to calculate your RNT, and adjusted NDL times.


edit: I see walter types faster than I do.

 

[RJP]

edit: I see walter types faster than I do.

Didn't have enough coffee yet and apparently I hit "enter" faster than I type.



I edited my post to include the second half of the thought, being "and take the info from the end of the first dive/slate onto the other slate to plan the next dive..." which Walter explained much better than my smart-ass attempt at answering the question.

:cool2:

 

[TMHeimer]

Thanks guys. Yeah, that's what I thought you use the RNT table from the second dive to plan the second dive. This was a problem taken from Nitrox class. It is an odd profile with the 36% being used for the first dive.