Building the Planks

In the plans and the kit version, the planks are out of three pieces each, joined with a butt block. I didn’t like this because I thought it would impede the bending of the plywood in those places. I really wanted to make them out of one long piece of ply, so I asked Janus the designer if I could do a 1:12 scarf joint. He replied 1:10 is enough.

I built a router sled out of some scrap wood and aluminum profiles that I “borrowed” from work and a jig for placing the ply boards with a 1:10 incline. Then I placed the bords spaced every 10 cm and went to work with the router sled. It took quiet a few passes since I was using my makita trim-router with an undersized bit… The shorter midsection will be turned over and receive the scarf on both ends.

I had ordered sapelli plywood bords that were 2.5m X 1.6m and after a lot of thinking and measuring and drawing out the curvature, I realized that I was able to cut out both topside and chin plank out of one board. Just barely though. In total for the 4 planks, I used three whole bords one of them would create the four middle pieces. Even though the chine plank appears smaller it’s actually the wider one due to the curvature of the hull. If you wish to replicate this and would like my measurements, then please reach out to me through my webpage.

After all the pieces were cut, I assembled the jig for the glue-up. All planks were glued at once. I used packing tape to tape over the semes so the planks wouldn’t stick together. The glue-up as well as the scarfing, needs to be ultra precise, since it is a blind glue-up and any gap in the joint would result in a failed bond. I did have nice squeeze out just by laying the pieces over one another. I put small screws on the edges to fix the pieces to the jig and then added a doubler over the top which I also screwed down into the floor to apply pressure.

I am happy with how everything turned out. Some of the thin edges had some tare out which I had to fill with epoxy. This will be visible when I show the Planking of the Boat.

In retrospect I must say that scarfing and joining plywood like this is very hard and difficult work and definitely not for the amateur builder with little experience. The slightest imperfection can result in failure and a little tear out in a “huge” gap. If I were to do it again, I would build it as designed by Janus and do the butt blocks and individual pieces.