Wow - fascinating! What a find!
This site:
http://www.ubootwaffe.net/index.html
offers a wealth of information regarding names of u-boat crews, u-boat locations by date, ships sunk by date, etc. Maybe you'll be able to figure out what boat it was!
Edit: oops, looks like maybe that was a very clever way of introducing the story of a fictional u-boat. Nicely done, if so, you had me convinced.