Rudder rake / drilling template

Why is it that if in “This old Hobie” it gives a basic rake measurement of 1” for the 17,18, and 20, And all boats use the same castings are blades, are the drill holes different location on the template? Especially the 18?

It depends on whether or not your 18 has the “old-style” or the “new-style” castings.

The old castings are unique to the 18 and use a different hole pattern than the new. They have a metal hook in the lower casting rather than a plastic cam which is used in the new castings. The new castings are shared by the 17, 18, 20, 21 and some others. The 20 uses a different rudder blade that is unique to that boat which is probably why it has a different hole location.

Keep in mind that the rake measurement is just a starting point. You need to sail the boat with the rudders locked down and and the sails trimmed properly and feel the helm. Adjust the rudder rake as needed to achieve a light weather helm.

sm