I am currently making a small plywood boat and needed a rudder. The boat is about 2m long and 80cm wide, im thinking this will turn it well.
The wood is 4mm plywood, epoxy is added to the rudder in order to make it more sturdy. The actual size of the rudder plate can be varried by making it longer or taller using more rudder holder segments.
M8 stainless threaded rod is used as the main shaft, 8internal 18external bearings from ebay are used for easy and smooth interaction between moving rudder and fixed attachment. All parts are held tight on the rod by nuts.
The distance between the two mounting holes is 180mm.
Please modify this as needed, custom bearing holes, distances etc. However I am happy with the base design and i bet it will hold up well for my usecase.
"Bouton_de_serrage_M8" is from another user, link to stl here: https://www.thingiverse.com/thing:1865629