I prefabricated the skeg a year ago when I was doing the small parts in my basement workshop.
The skeg plan
First I made a positive mold which was covered with fiberglass. There is even a 3D model of the skeg that you can use to have the shape milled. Since I don’t have access to 3D milling. I glued two 20mm Styrodur plates together. With my orbital sander i reduced them to 38mm thickness. With 2x 1mm glass fiber laminate I get the necessary width of 40mm.
This positive skeg model had to be insulated with adhesive tape. Then i applied some layers of 300g/m2 fiberglass fabric.
Removing the Styrodur material from the skeg mold was a bit tiring.
The skeg is bolted to the hull. I bought 6 M10x120mm V4A screws and V4A rods. I clamped the screws into a jig. The welding of the skegbolts was done by a professional welder.
The welding jig
The skeg bolts must be casted in the skeg mold and the mold has to be filled up with epoxy resin. This must be done step by step because of the generated heat when the resin is curing. The M10 skeg bolts must not protrude more than 5.5 cm above the edge of the skeg mold.
5,5 cm is the optimum bolt lengths.
I added microballoons to the last layer so that I can sand it easily and adapt it to the hull.
After the hull was planked and laminated, I marked the centerline of the boat with the laser level and drilled the holes for the 6 skeg bolts. From the inside I attached a 10mm thick plywood panel as per plan. I glued the skeg to the hull with a mixture of epoxy and cotton fibers and fixed it with the bolts to the hull. I also laminated the transition from the skeg to the hull with fiberglass tape.
Skeg glued and laminated to the hull.
You have to be careful that the rear bolt is not too far aft, otherwise you will have problems screwing it on to the transom frame wood.
Rear skeg bolt very narrow to the transom frame. This is maybe the problem because i added a plywood doubler to the bottom of the transom.
The skeg bolts, nuts and washers in stainless steel V4A quality from the inside of the hull with a plywood doubler as per plan.