Some additional info - just sunk a passenger/cargo ship, total time between "torpedo impact!" and "she is going down" 60 minutes, still counted as a "kill".
Ship was hit a bit stern for the sweet spot, several times the fire broke out aboard and was snuffed again. 3,3 km distance.
Weather: storm on approach, medium height waves.
I really don't get it.
is it the distance that makes difference between "ship sunk on itself" and "kill"?