GoldenRivet, I've been looking for this legendary handbook everyone seems to refer to here in the forum. My ears (?) perked up when I read that you have an online copy of it bookmarked for reading.
Is this the same 1943 U-boat Commander's Handbook that is archived at hnsa.gov? That one seems, to me, to be very short and skimpy on details for it to be the rich and vital document I have seen described here at SubSim.
I'd very much appreciate your providing the link.