When I began building, I was very concerned about the correct plank dimensions, and tried to spile the outline using a spiling pattern to transfer the plank position from the molds and previous plank’s edges to the plywood stock. After a while I realized how accurate the planking pattern on Doug Hylan’s plan is, and that cutting the planks a bit oversized eliminates the need for spiling. I settled on using the following procedure:

To determine the right plank size, the plank is cut oversize relative to the dimensions on the plan. Then the plank is screwed onto the hull, and the correct width is scribed using a comb-like gauge. The inside fork of the gauge rests inside the hull on the edge of the previous plank, or, for the lower edge, on the  position for the plank as marked on the molds, and the outside forks are used to scribe the  correct plank width on the outside of the hull.

Determining plank size