Cutting a destroyer in half...

[Sailor Steve]

Originally Posted by GoldenRivet

U-505 was even stuck in repairs for several days because it brushed a jetty or pier of some sort - the minor damage sustained in the low speed collision rendered it completely unable to dive.

I never thought of that before, but it actually makes perfect sense. The pressure hull of a submarine is several times thicker than the hull of a destroyer. The DD's hull is 1/4" (about 6mm) of mild standard steel. The pressure hull of a u-boat was about .85" (20 mm) of hardened tensile steel. This makes it sound like the u-boat would be much stronger, and for submerging - and surfacing again - it is. But what happens when your car gets into even the slightest bump? The hood gets sprung. The doors get sprung. So what happens when the u-boat hits or gets hit by another ship, especially one weighing between two and four times as much? The pressure hull might not get hurt at all, but if it flexes even a little, the torpedo doors get sprung. The hatches get sprung. And those torpedo doors are underwater all the time.

Glug.