Mike Corcoran and I have built many rudders and below is our latest thinking. They are similar but have slight differences. My rudder is shown here. Mikes rudder is shown here. I believe this is the best shape for a rudder and tried to make my rudder to this shape.
Station points begin at zero at the nose.
You can thus use the table to scale for any width foil. Remember these measurements were made to lay out airplane wings. You can shape the whole blade in about an hour with a perfect shape. The jig does take about an hour to make, but once made can be used over and over. When I build a rudder this winter according to Mike's specs, I will make a jig that will last and perhaps pass it around to those on the list who are interested in building his rudder.