Dive planning question

[Walt1957]

I have seen it mentioned in quite a few places that it is anywhere from important to imperative that the deepest dive be first and that all dives be shallower than the previous.

Besides giving more BT is there a significant reason? My wife wants to book two sets of two-tank dives that are 40' and 30' in the same day. There is about 45 mins SI between the 40' and 30', and about 2.5-3 hrs between the two trips. Is this truely unsafe? If so they could stay at 30' on the third dive, but is that necessary?

Thanks

 

[Michael Schlink]

DAN came out with a report a while back about "reverse profiles". Although I think it will always be better if you can dive the deeper dive first I believe things have lightened up a bit. IMHO you'd be just fine doing a 40 and a 30 and coming back to do it again later in the day

 

[Scuba_Steve]

I'm not one to throw caution to the wind, but dude I wouldn't lose 1/100 of a second sleep over that one.

Have fun.