Centerboard progress

The centerboard and rudder are nearing completion. This has been one of the more labor-intensive projects so far. The plans give general instructions on shaping the profile of the blades, but I decided to try to get something close to a NACA section for (hopefully) a bit of improved performance. The link is to a Duckworks article by Warren Messer on a method for producing blades with this profile. I didn't go crazy here. I just plugged in some numbers for my blade dimensions to get a profile which I used to "eyeball" my blade as I was shaping it. I'm sure it's far from perfect, but I think it will be an improvement over what I would have produced with the the stock plans.

Here is the rough blank with the control appendage. It had been rough-shaped at this point.




After comparing the rough shaping with the NACA dimensions, I needed to do some fairing. This was done with an epoxy and phenolic micro-balloons mixture mixed to a fairly thick, non-sagging consistency. After curing for a couple days, I hit it with a fairing board while frequently checking against the NACA profile.


After several iterations of compound and fairing board I had a shape I could live with. Like I said, not perfect, but pretty good. Then I "rattle-bombed" it with a can of white appliance epoxy. This stuff goes on thin and dries very hard. I will probably give it two or three more coats of the stuff before I call it done. Here is how it looks now.