Haha, finally got one..
I am not playing DID, but wanna survive as long as possible. Before, thus untill now I get away from them as the plaque.. they are not worth an eel.. just 1250 tons, is nothing.
But, normally I fire at the merchant, and then dive as mad and try to get away.. what always succeeded.
Now, in the Med, I had a very persistant Brit who wouldnt gave up, it was a Black Swan (who on earth comes up with this) and a big merchant.. sunk it.
Well, eventually I got sick of it after an hour, he came closer and closer, I ordered zero tieffe, and fired a torp, while he was about 300 meters away.. BAM! gone is that hot potato!
I dont think I do it again.. wanna keep the crew save and thru the war.