[UnderseaLcpl]

I have very little luck with flanking away after an attack. They seem to pick me up immediately. When I crawl away I can usually get a decent gap as they navigate amongst the remaining merchants.

Also, a spread of four torpedoes seems a waste on an escort. I see you correctly estimated their speed at 12kts. They always circle at close to that speed. But if you know their speed and they are circling 'round for another run it should be fairly easy to hit them at nearly 90.

A bit of advice for those escorts, which you may have seen me repeat, endlessly, in other posts; Once they run over you and begin to turn around just go full rudder in their direction at 1/3 or slow speed. For small escorts like Flowers you may have to go to standard for a bit. Don't even bother to input data into the TDC, just set fire bearing to zero for a target with a speed of zero knots.
Open the tube you wish to use. If using a fast steam torpedo fire when he is 10-12 degrees from the zero mark as his prow crosses your reticle. Electrics are roughly 33% slower so use a 15 or 16 degree lead for those. Always use impact unless the seas are rough and always use a 1.5 or 1m depth for impact.
One hit, if it doesn't blow them to pieces, will at least immobilize or severely cripple them.
Now you have 3 torpedoes left for the other escorts or some nice, fat tankers.