HELP!! OK..I think I got the first part...but not the second.
Day 1-
Dive #1 100 feet for 10 minutes (which means we are in PG E)
Dive #2 60 feet for 20 minutes (which means the RNT was 11, the ABT was 20 minutes and the TBT is 31 minutes/the SI is 1:00 hr) which puts us at PG B
Dive #3 40 feet for 30 minutes (which means the RNT is 9, ABT is 30 and TBT is 39) my new PG is L and after a SI of 2:15, we would end the day at PG A
Right??? Oh please be right
Looks like you've got most of it right. Remember to take note of your pressure group at the end of the dive and at the end of the SI.
Dive 1 - 100ft for 10 mins, you're indeed in PG E
SI of 1:00 puts you in B. so far so good.
Dive 2 - 60ft for 20 mins. RNT is 11, ABT is 20, TBT is 31 minutes. This puts you in L.
SI of 2:15 puts you into PG A.
Dive 3 - 40ft for 30 mins. RNT is 9, ABT is 30, so TBT is indeed 39. This puts you into group I at the end of your dive day.
Work out each section before moving on to the next (dives and SI's) or you'll miss something, which is what looks to have happened here.
Day 2 I picked 40 feet for 30
The first PG would be F and the second would be V...but there is no intersection of F on the diagonal and V at the bottom???
Help please
Determining the minimal SI is the trickest part of these tables to me
That dive would indeed put you into F, but I'm not sure where you're getting the V from.
I'll give you my own example to see if I can help you here.
Lets say Dive 1 is 60ft for 35 mins and Dive 2 is going to be at 50ft for 45 mins.
At the end of Dive 1, I'd be in PG N. Now look at table 3 (where you got your RNTs) to find out what post-SI pressure group has an adjusted NDL of atleast 45 mins. PG J has an adjusted NDL of 47 mins. The intersection of N and J gives a surface time of 0:19 - 0:24. So the minimum surface interval required to do these dives would be 19 minutes.
Hope this helps.
EDIT: ok, I see where you're getting the V from. You have the right idea. The reason there's no intersection is that there's no minimum surface interval required to do these dives. At 40ft, the NDL is 140 mins, so even doing 2 30 minute dives back to back is still within NDL, meaning that no surface interval is required.