AfterDark
Contributor
But the point is his only planning tools appear to be tables that he apparently doesn't have or perhaps even know how to use....so the only safe assumption for him is a square profile, so the only safe answer for him is to shorten the second dive. If he uses the PADI RDP, the first dive (50 ft) puts him in PG O, which after a 75 min SI is PG E. That's 13 mins of RNT at 75 (80) ft, so his remaining BT is just 13 mins. He could do a 13 min dive, but not a 45 min dive.
If he has a computer, the game changes....but only a little. Even if his first dive (being multi-level plus a 75 min SI) gives him zero residual nitrogen, he still can't go to 75 ft for 45 mins on the second dive. His second dive must also be multilevel, and most likely aslo considerably less than 45 mins.
The only safe answer is no answer so he can't blame you after he screws the pooch.