Attached are 3 variants of a single simple design. Its a rudder servo mount + rudder post, designed to be used with my rudder gears. One is set for a single rudder, one is set for dual rudders, and the final is dual rudders with a 2.5" idler gear to space the rudder servo closer farther into the boat for ships with shallow sterns.
I print with ABS, 2mm walls 20% infill. I can't account for every hull shape, these mounts are designed for you to print them and then sand to shape. Servo mounting uses the heatset inserts described in the rudder gear resource post.