J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Rudder(s)

Here are some images from today's progress. I have added some round head screws to the router base to insure that it does not rock on the offset rails and a pair of extra holes on each side of the base so that when I get to the nose section I can hopefully keep the whole thing stable. My plan for the bigger flat sections is to use a very large 2" diameter bit and take relatively light cuts on each pass. This has worked well on the tables I make. The advantage to the large bit is that it runs much cooler and so stays sharp far longer than a small diameter bit. The downside in this application is that if the router rocks on the rails the edges of the bit will dig in. The large diameter will also be hogging out material from the area on the next pass too.

I also made a minor change to my plan and decided to add one more thick piece on the front side of the blank. Doing this moves the entire foil profile forward and gives me more machining stock on the rear side. It also meant that an area that was rough stock that was going to get milled off now needs to get filled in.

I also used my very elaborate computer overlay system where I actually lay the old rudder over the blank to triple check I have laid out the various key features correctly. In the upper section the rudder is not completely milled to the foil shape in the area between the straps and I do want to maintain the basic appearance of the rudder above the waterline. If I do this right you will never know this is a balanced rudder because the added 2-1/2" of material is all below the waterline.

Tomorrow I will trim the blank square, add my centering and elevation arms and start making a lot of sawdust. I intend to weigh this blank before I mill it, but I may have to call in a crane to get it off my bench. I suspect that the blank will lose 2/3rds of it weight in the milling step. Then it likely will gain a 3rd of that weight back when I glass it up.