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?
Rooster of Doom
13th Jun 2005
Das Boot (1981)
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.