There is a small plastic screw on the side of the rudder mount that attaches to the back of the yak. It screws into the rudder side of the mount about 1/2" and will lock it down until you are in very rough conditions or go above 10mph on an extended run.
I thought of this but the problem I have with this is that all of the fresh water lakes near me that I can sail on have to many weeds near the shore for me to be able to lock down the rudder. In Lake St Clair I have to get out a good 1/2 mile before I bother with tipping up the rudder to dump the weeds that have collected on it. Sometimes I have to do it more than once because of the course I have to take.
Check your Port and Starboard rudder deflection out of the water. Mine was off a bit. You can readjust your control lines to correct if necessary.
I will check this again, I wonder if its possible for the cables inside the hull to get stuck or caught on something? Dose anyone know of an easy way to check this?
Thanks for the responses...