So I had some time and somewhat warm weather to take the blades out of the basement and start to cut out the delam spot and sand over everything else. On the STB trailing edge I had a crack / delam and ((((((( cracks on both sides. I cut it all out in a 1/2 moon shape and gave a quick taper with the dremel.
The west system book calls for a 12:1 taper for patching holes. That would be a 6" taper on both sides of the board. This seems a little much right now i have about 1.5 inches and will expand that out 2-2.5 unless I really need to go to 6 inches.
I plan on cutting 4-6 fiberglass patches and laminating them. For support I've see some guys using tacks as a "rebar" in the middle to give the fiberglass something else to hold onto. I think I may go that route and then fill it in with 406 and 407 then laminate the whole blade and paint it. The rest of the blade is ok but needs some knicks and dents sanded and filled. While I got the epoxy out I may as well do it right. Since I'm painting the boat I'll paint the rudders and practice my roll and tip.
I'll post this all up in the tech section once I'm done with it.
I wouldn't use the re-bar idea, this could be a rust / delam issue in the future. But make sure you "wet out" the area and let it cure SLOWLY, this is going to be the bond to your rudder. The slower the set of the wet out stage the longer the resin has to migrate into the scratches in the rudder.
If you use filler do so just for the very last few layers, 406 and 407 have almost no structural abilities.
Your goal, especially on a rudder, is strength so you want a high fabric to resin ratio. Without a vacuum bag this will take some time to do. Be very careful, if you go to fast and build up a high resin to fabric ratio the entire repair can literally "pop" out, or crack under your final layer of glass.
I hope this helps, I have had the "pop" out happen to me LOL, but wasn't funny at the time π
Sorry you don't live closer I would lend you my vacuum pump and some release fabric.
PS. don't worry to much about the 12-1 ratio, but do what you can, the more purchase you have on the rudder the stronger the bond.