I thought I had read where if you filed the trailing edge of the rudder very lightly on just one side at about 40 degrees that it broke up the cavitation of the two flows coming back together and reduced vibration (from this cause). Can anyone help to verify this? Or to privide what the trailing edge should be (blunt, evenly angled, rounded or one sided)?

I have another person with the problem and I remember reading that somewhere regarding cat rudders and would like to verify this.

Thanks. Paul

i've heard smoothing the mould line out of the LEADING edge of the rudder can help vibration problems, never heard trailing edge. As far as drag is concerned i think you want the trailing edge to be as sharp as practical for the material

A blunt trailing edge will give a hum or vibration make them as nice and sharp as you can.

correct, I would sand down to tapered, fine edge.
some people like the hum sound.

Thanks guys. I guess I was wrong what I had thought I had read. Sharper does make more sense so will go with that.