Yeah, I play it unmodded, and I was getting kinda curious myself as to why in 3 patrols I had only encountered, and sumarily sent to the bottom of the ocean, two british J-Classes out of many merchant convoys.
I'm fairly new and still learning the game, but I defeated a J-Class with what I thought was an insane feat of awesomeness (but I highly doubt that since many of you other captains have probably done this lotsa times). Basically I surfaced right in front of her and essentially mooned the jerk. They instantly cranked that ship full rudder and gunned her straight at my face at flank speed.
In the time it took her to cross that expanse of water, I went to periscope depth, calculated two torp shots straight at her bow, and let em rip...
Lucky for me, she saw them, tried to evade and went hard starboard. Both torps struck her midships...Kersploosh, one soggy J-Class...
Captain must've been greener than me, LOL!
Erm...back to the present topic, thank you Wolfhound for asking this question, I was begining to wonder myself if historically there weren't many escorts around.
