Plot hole: After the first attack on the U96 the captain decides to resurface after sunset. However when they do resurface it's broad daylight.
Das Boot (1981)
1 plot hole
Directed by: Wolfgang Petersen
Starring: Jurgen Prochnow, Herbert Gronemeyer, Hubertus Bengsch, Klaus Wennemann
Revealing mistake: In one scene just before the attack on a big Hunter the young captain (Jürgen Prochnow) is sitting with his charts. Beside him he has got a glass of beer standing. The sub lurches heavily right and left in the hard weather, but the surface of the liquid stays the same.
2nd Lieutenant: First time on U-boat?
Lt. Werner: Yeah. First time. It's gonna be exciting.
2nd Lieutenant: Do you have a will?
Lt. Werner: Excuse Me?
2nd Lieutenant: 13 boats down last moth. Sank with men and mice. Exciting, huh?
Question: I know practically nothing about submarines, so this seemed a bit strange to me. When there's that huge storm, why do they keep staying at the surface, only going down for an hour at a time?
Answer: Because that's what the U-boat was designed to do. Unlike modern nuclear boats, they didn't have the capacity to stay submerged for long periods - basically just as long as the air lasted; there wasn't atmosphere control equipment. They would 'snorkel' near the surface, recharge the batteries with the diesel engines, and then dive for a few hours at most before having to come back up and repeat the process.
Answer: U-boats also travelled much faster on the surface...about 18 knots, vs only 8 knots or so beneath the surface.