Yeah it's a great film, and certainly one of my favourites. And like everyone else is saying in terms of characters (and I know it comes from a book which honestly I haven't really read) I also think a significant flaw exists with the First Officer character, which everyone naturally likes to make fun of because of his obvious stereotype (being a Nazi).
I mean, as the First Officer, we would assume that this guy has had his fair share of patrols and is gearing up to take command of his own U-boat sometime soon. He does have his moments: Such as taking on the historically correct firing duty during the night time surface attack, and being ordered to 'take over' during an underwater emergency event where the Kaleun had to be elsewhere outside the control room. Notwithstanding, the character really doesn't live up to what one might expect from history, and I think that's a fundamental flaw with the script.
Furthermore, I'm thoroughly disappointed that in this aptly named thread (we are already on Page 2 here) no one has yet mentioned the single most obvious and important nutritional item to be found on a U-boat. The obligatory:
U-boat Special Cocktail! 
