Welcome Captain
Sailor Steve is correct. It is the Basic.cfg that needs to be edited.
I changed it from -1 to 0 too. So you won't get punished, but won't get rewarded either.
I figure that the wasted torpedoes, and wasted time and effort I put into the attack is punishment enough!
In the interior view are a couple of gauges that show your RPM. I like to stay between 50-100 rpm when being hunted. You may have to manually set your speed to 1 or 2 knots to achieve this, rather that using the Ahead Slow command.