Hello,
I wonder when music was allowed on u-boats? Also, were the crew allowed to make as much noise as they want outside of combat situations like they did in a few parts of Das Boot?
..or these things were allowed only on friendly waters, during specific hours to let people sleep etc.?
I would appreciate help on this one very much!

The boat gets pretty noisy at times in our game UBOOT and I wonder how realistic is that, considering that noise may be detected by the enemy.