Impatience and greed will kill you in this game.
Later in the war, from mid-late '42 onward, night surface attacks become more and more difficult. The escorts are starting to have radar and the radar improves over time. It becomes extremely difficult to penetrate the screen. Daylight submerged attacks against the convoy become a better option most of the time. Even that becomes difficult with sonar improving, not to mention the escorts are just getting better.
In either case,submerged or surfaced, being forced to shoot from outside the screen happens more and more which means longer ranged shots than you may be used to.
