Lastnight I came across a Taskforce escorting and Nelson Class Battleship. I guess I was in the right spot to shoot.... north if the Taskforce and within 800 meters of the closest escort, but sitting there not moving. Sent off 4 torpedos at 90° and nailed her. Now there had to be 12 escorts around her. 5 broke off to hunt me down. As soon at it got a confirmation she was toast I dove to 45 meters at full speed, and turned 90° from my attack heading directly towards the the battleship. All 5 bore down on where I fired from and pounded that area. Just shy of where she was going down I turned again, dropped to 2kts and headed south away from the escorts. Took 3 hours real time to sneek off but they never found me. Now for some unknown reason I couldn't get Silent Running activated... and that didn't seem to matter.
Sometimes if you can get between those attacking you and the ship you torpedoed, the noise it makes will mask your Uboat. You can then slip quietly away. I've slipped up to a ship that's sinking very slowly and waited out the escorts which finally gave up in a short time, and then slipped away. I've found out they won't come close to a sinking ship. I guess it all adds up to the tactics you use...... and a lot of luck. Just don't get too close or that ship will take you down with it.