I have had rudders on kayaks that I never used. My problem with this boat is the wind will not let the boat track downwind. It turns the boat into the wind and this is the most powerful weathercocking I have ever experienced in a kayak.To fight this I use sweep strokes on one side of the boat. My speed drops and then the boat feels very unstable. By putting the rudder down it keeps the wind from turning the boat. I can paddle to move the boat rather than putting a lot of energy into keeping the boat on track.
My boat is 21 inches wide with a very round bottom profile. Without speed, it feels very unstable in chop.
A lot of this is just getting used to how the boat handles conditions. They are all different. Each one I have had has its great qualities and its qualities that require experience to overcome.
Just never had a rudder dependent boat before.