Honestly I can't remember hitting any target
intentionally at more than 1,500 or 2,000 meters.
There have been cases where I missed a closer target and had the torpedo hit another one several thousand meters away on the other side of the convoy (but how far exactly? Who knows?). It's actually a nice surprise when after getting pounded by an escort and creeping away to see a ship you don't remember shooting at in your logbook.
