Which tables do I use?

[lamont]

i tend to chop rec dives up into deep, medium and shallow portions, which roughly correspond to 0-30, 30-60 and 70-110 feet. do your NDL dive for the deep portion using depth averaging for it (as long as it isn't too much of a reverse profile). then scoot up to 60 feet and move from 60->30 feet spending no more than about 20 minutes there. then scoot up to 30 feet and move 30->surface doing "decompression".

for your profile above i would say 'it doesn't matter'. when it matters is when you're out there at 20 mins @ 100 feet on 21% or 30 mins @ 110 feet on 32%. do the move you did from 70->40 (4mins?) only from ~100 to 60 to stop ongassing -- and maybe even a bit faster. then you've got 20 mins to move to 30 feet. then do roughly the profile that you did from 30 feet to the surface. do at least 2-2-2 and 15 or 30 minutes can't hurt if there's something to look at and you've got gas and you don't need to pee... the more you push it deep or push it medium then the more you need to pad your ascent to the surface, but something like 5-5-5 to the surface will clean up a large amount of being too liberal with the NDLs deep.

what you did i'd call 18 mins @ 80 feet. and since you were on 21% you can't pause at 60 feet like you can on 32% and you need to move shallower, so the 70->40 move you did is more appropriate for that gas (although it didn't matter as much since you were nowhere close to your NDL limit).

 

[RTodd]

You guys are making this too complicated. You could do this dive on a PADI air table. 100 for 20 minutes (I assume that is within the RDP nodeco limit), find your exit pressure group, then use that as your residual for the 50' portion. Given the profile, that example has plenty of padding. Convert for EAD or use a 32% table and you have even more padding. The PADI wheel actually allows this but if you use basic common sense you can do the same thing with the tables. The concepts that lamont and others are discussing are great, but until you can get the concept that dives like this are easily within even PADI table limits, you will probably miss the point of the general rules of thumb.

 

[b1gcountry]

I would probably just think of this particular dive as 16 min at 100' with a nice, slow ascent, and an extra stop at 30'. A lot of my square profiles look like this.

Tom