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.
Interesting process! It’s impressive how detailed and methodical the skeg construction is, especially with the use of fiberglass and epoxy resin. I’m curious, though, why you chose Styrodur for the mold instead of a more traditional material—was it for ease of shaping or cost efficiency? The step-by-step curing of the resin to manage heat is a smart move, but I wonder if there’s a risk of warping if the process isn’t perfectly timed. Also, how did you ensure the skeg bolts were perfectly aligned with the hull during installation? The addition of microballoons for easier sanding seems like a clever trick—did it work as well as you expected? Lastly, do you think the plywood doubler might have caused the issue with the rear bolt, or was it something else? Would love to hear your thoughts!
Wow, that’s quite a detailed process! I’m impressed by the precision and effort you put into making the skeg. Using Styrodur and fiberglass seems like a smart way to achieve the right thickness and strength. I’m curious, though, how did you ensure the skeg was perfectly aligned with the hull? The step with the laser level sounds crucial, but did you face any challenges during that part? Also, adding microballoons for easier sanding is a great tip—did you experiment with other materials before settling on that? I wonder if there’s a reason you chose V4A screws specifically—are they more durable in marine environments? Lastly, do you think the plywood doubler might have affected the alignment of the rear bolt? I’d love to hear more about your experience with this project!
This is a fascinating process of building a skeg! I’m impressed by the level of detail and precision you’ve put into this project. Using Styrodur and fiberglass seems like a smart way to achieve the desired shape without access to 3D milling. I’m curious, though, how did you ensure the epoxy resin cured evenly without warping the mold? The addition of microballoons for easier sanding is a clever touch—did you experiment with other materials before settling on this? I wonder if the plywood doubler could have been designed differently to avoid the issue with the rear bolt being too close to the transom frame. Overall, it’s inspiring to see such dedication to craftsmanship—would you consider sharing more about the challenges you faced during the welding or lamination process?