... once you learn it, you never forget.
I sailed to a patrol after 6 months of absence, and first thing I noticed is that I forgot most of the keyboard controls. I wanted to pause and I instinctively pressed "P". In the harbor.

AUSBLASEN!!! Now where did I put my manual?
After the initial hardships, I encountered a convoy, during pitch black night and rough seas. I thought it will mean a quick death for me, but then it all clicked. I fired 4 eels and disappeared in the darkness. Two radar equipped Black Swans didn't have a clue where to look.
Despite the large distance (5km, 4km and 3km), all torpedoes hit their targets; two ships wend down right away, one stayed afloat, but motionless. I'm glad I didn't forget how to do manual targeting.
The night is still young, and there's plenty more targets for my eels.