When running at cruising speed I thought it was normal for a single screw boat to be more difficult to turn the helm in one direction than the other. When I take may hand off the wheel of my 26' Sisu it stays where I leave it, but it does take more effort to turn the wheel to starboard than to port. I thought it was due to the rotation of the prop.
Yes, I think it is normal unless it has been "trimmed out". Your Sisu may have a type of steering that does not give feedback through the wheel therefore it stays where you put it even though it wants to turn back.
Anyway, my friends boat has properly working, 2 station, hydraulic steering with the "anti feedback" valves in place so, like you, he gets no feedback either*. But it is twice as hard to turn to starboard as to port, maybe more than twice.
So I was asking if a wedge should be applied to the upper or lower 1/2 of the rudder to correct the imbalance.
Lacking any feedback from the forum, yesterday we screwed on a 3" x 1/2" wedge, 1/2 the height of the rudder, to the portside trailing edge of the rudder at the
bottom. The result was that it not only solved the problem but actually went slightly the other way (a little harder turning to port now) I think if we shorten this wedge a little we are going to be right on.
I hope this helps some other imbalanced soul...
* These valves must be in place on 2 station steering but not on single station.