Spiling - What's Spiling?

I tried my hand at spiling for the first time yesterday. Spiling? What's spiling? 

Spiling is the process for copying and transfering the shape of a plank to your stock, be it a piece of plywood or a board.

It's time for me to do my planking. I've already done my keel plank and I went ahead and copied Clint's dimensions for it. I knew there would be some "play" in it fore and aft. It was symmetrical across. However, the other planks are not symmetrical. I don't trust myself to have gotten the setup up my strongback and molds close enough for Clint's dimensions to fit. They might. They might not. I felt spiling would be the safest method, even though I've never done it. 

Here's how the first effort went.

I had made my "compass" and spiling battens a few days earlier and already posted. The battens are seen stacked next to my keel plank in the "hole" picture. 

I started by temporarily attaching my battens to the location of the garboard plank.

Then I measured the distance from a point on the batten at the molds to the edges of the desired plank and marked these on the batten.

Next I removed the batten and transferred all those measurements to the plywood. I then connect the "dots" with a batten, mark new points equidistant from that line which will allow for the offset of your saw and blade, reattach the batten on those new points and cut. 

I tried to cut both garboards at the same time to save time and trouble. The Rotozip just wasn't powerful enough so I switched to the 3.5" saw. As long as I didn't let the blade get too deep, it made the curves OK. It was tight, but it made it. 

Here's the garboard dry-fitted.

It came out OK, but as you can see, there is a 1/4" gap (the second plank is just lying there and not fitted). I'm thinking my spiling batten made have been too flimsy. I can fill this gap since the keel plank and garboard butt up edge to edge. I'm going to rip a strip of leftover ply and lay it in the gap. It will be epoxied and covered with fiberglass inside and out. 

I don't want to have this big of a mistake with the other planks because they overlap. I'm going to purchase a piece of luan and cut two more spiling battens that will be stiffer then the first ones. Hopefully that will give me a more accurate plank. 

All in all, not too bad for the first try. I've got to get the next ones pretty close, hopefully within 1/8". I really don't want to mess up and have to buy more plywood. That would be an expensive mistake!