ComPac will upgrade our old flat blades with the foil rudder on the Mod 4s. It has the stainless steel locking tab and pull up handle. They also send you new bronze bushings.
The preferred way is to ship your old rudder back to the factory. Instead, the sent me an undrilled rudder and told me how to drill the new one. It took some effort to align, but installation was easy. Drill the handle hole so there will be some spring pressure to hold the rudder in the down position. Drill out the old bushings with 1/2 inch drill. Press in the new bushings with a C clamp. No more sloppy rudder from worn bushings. An unexpected benefit is how much better the rudder responds while motoring. Almost no pull from prop suction. I like it.
Maybe Delightful is now a Mod 3.5! She sails better.
Interesting...What is the cost of this upgrade and how does it compare to just purchasing from Idasailer (which I am about to do)???
Might be best to call Com-Pac to discuss options. It looks like you have three different options. IdaSailor rudder blade, Com-Pac rudder upgrade, IdaSailor full rudder upgrade. I suspect all will perform well in the water. Each has a different way to hold the rudder down. Each has a different way to hold the rudder out of the water. It looks like the IdaSailor full rudder upgrade really gets the the rudder out of the water. My new Com-Pac rudder does not come completely out of the water - at least yet. I am thinking of some adjustments for that.
I finally got around to posting the "instruction" picture from Com-Pac. It is at http://com-pacowners.com/gallery2/displayimage.php?album=lastup&cat=0&pos=0 on the gallery. Still happy with the result.