A speed of 2-3 knots would have been enough to secure Bismarck’s escape. The only reason the British caught her was that she was steaming in their direction, unable to do otherwise. I don’t believe the thrusters would have to counteract the jammed rudder. The ship was able to get out of its circular course but could not fix on any steady course. The rudders were, I believe, a non-factor at that point. If thrusters offered prospects for escape, the Germans also had the option of blowing off the rudders, something they opted against historically.