Desparation spread from a botched intercept course at a Carrier just prior to the Bismark sinking.
4,350ish meters.
1 fish hit an escorting cruiser that was starting to turn having spotted the bubble trail.
The carrier was on a turn but it was to late, 2-eels w/1-keel shot put her to a stop with the bow in the water. 1 eel missed. Finished her off with a stern shot a short time later.
I would also agree with most when normal attacks especially on convoys are under or around 800m. It's great sneaking in between columns and getting the timing close for a double. Especialy when one's a fat tanker. That's like game cleavage.