Engine controls question...

[Enigma]

So, ima long time player, so I think I know the answer to this, but the game keeps suprising me and I always learn something with each patrol...so...

its 1944, Im currently in a VIIC. (Sunk my first aircraft carrier today. Hoorah!)

In two recent patrols, ive had my rudder blown off by depth charges. Ive managed to survive and make it home both times..(Cheating of course, by selecting return to base. I can only sail in a straight line once the rudder is blown off....)

My first instinct when it happened was to use the engines at different power setting, thus sterring the boat without use of a rudder. However, I cant find a way to do it. I see the 2 seperate tach;'s and power setting guages for each individual engine in the conning tower, but touching them does nothing. Am I to beleive in a sub sim as comprehnsive as this that I cant control my engines seperatly!? Was this left out of the game or am i missing something??