Hey rik, good to know I'm not the only old one here
the commander who helped them with SH3 was Jürgen Östen:
http://www.uboat.net/men/oesten.htm 
I have all the video interviews with him that were made for the game in my HDD, and IIRC they are still available for download in the SH3 official web (Pity they only asked him general things they could have gotten elsewhere, instead of the technical details that will now be lost after such men die
)