I had a situation the other night where I had 2 DD's detach from a convoy I had just attacked. I was about 6KM away, heading away & running silent. They picked me up and all heck broke loose.. I replayed that 'recent save' several times and tried other ways of evading, but they kept finding/destroying me.. I finally raised the scope & schnorkle and hauled butt out of there.. Of course they zigzagged after me, but 500 meters away, they started their straight run.. By then I was doing about 12 kts, making lots of noise. Around 450 meters I let loose with a stern shot .5M under their keel.. Sank the first escort & the second escort ran the same way.. She sank too
Luckily I had electrics in the stern tubes so they didn't spot the bubbles..
Good Hunting!