Repairing a Rudder with Polyethylene Glycol

[Dantodd]

If you want to dry out the rudder wouldn't it be easiest to just cook it in an oven for a couple days?

 

[Robert M.]

Couple of points:

1. I agree with the comments that corrosion of the SS web and its welds are the most important concern.

2. I don't agree with the comment about splitting the rudder into two shells. First, it can be very difficult to do. Second, assembling the rudder stock and the repaired shells is extremely difficult to do well. Without a jig, proper alignment of the shells around the shaft and web would be a nightmare.

3. The method I've used is to open windows through the skin on one side of the rudder. (Use the other side to serve as a form to help restore the original shape of the repaired side.) Then remove the failed core material and replace it with blocks, either balsa or a synthetic core material, buttered with resin putty.

4. Then restore and fair the skin of the repaired side with new fiberglass laminate. Then remove the failed fiberglass of the other skin and repair and fair it to the original shape.

5. The area at the top of a typical spade rudder is often the biggest part of the problem regarding water penetration and should receive special attention. A thin fiberglass shell is often bonded to the stock with resin putty that has separated from the stock, allowing water penetration. After taking measurements, remove all of the original material. Then mold new fiberglass laminate completely around the stock with resin and CSM. Mold and fair it to the original shape.

6. One trick others have used is to create a shallow groove in the top surface of the fiberglass shell around the shaft. Then fill the groove with 3M's 5200, providing a flexible seam between the shell and shaft. This trick isn't necessary if the repair has been done as outlined in 5. above.

Here are a few relevant pics of my Sabre 28 rudder, circa 1992. The failed core material has been replaced with balsa core blocks and a resin putty, consisting of Cab-O-Sil TS-720 whipped into CoREZYN vinyl ester resin. The rudder shaft and much of the web, particularly the welds, have been exposed. The rudder in the first two photos is nearly ready to be finished with new fiberglass laminate consisting of CSM molded with the CoREZYN. The third pic shows the finished rudder after it's been faired to its original shape and coated with polyester gelcoat. All of its new fiberglass laminate, most importantly around the exposed shaft, was molded with CSM. And after 20 years there are no cracks anywhere and, according to my moisture meter, the inside is bone dry!