The block and tackle under the cabin deck give a 1:4 purchase, so it takes 4 times the force to move the rudder from outside the boat (as a wave would do when hitting the rudder) than moving the rudder using the steering rope. The rope is tightest when the rudder is straight, and somewhat slack when pulled/pushed over, so there is a feel for the rudder angle (marking the rope helps, in addition).
The advantage is that the rudder won't move from where you set it. The rope steering is very nice, one can steer from anywhere in the boat, very handy when picking up a mooring line or an anchor. It takes a bit getting used to, but then it becomes second nature.
The boat steers itself, once set on a course, and adjusts to windshifts without much steering (has nothing to do with the rope steering but with the great design job of N.G. Herreshoff.
This is a great boat!
Best,