I regret, Sir! A german u-boat had no quality lacks! In fact the boat was commissioned in 1944, almost 70 years ago, but my picture was taken yesterday! What you can see is a fatigue tear due to its long action.
magic
the affix "40" is a counter for all terms in the basic.cfg file. For the IXC boats, it starts in 1940 with "00", 1941 with "10" and so on. "40" means 1944 in this case.
I changed the conning type ("Turm") for 1944 to include privateer´s turm1 construction. It should work although i haven´t tested it with your big mod.
Greetings.