Shop Talk: Planking aides
from Bill Whitney
Undoubtedly these ideas are not original to me, since plywood boats are older than I am, but I have not seen these techniques in your book or WebLetter. This concerns hull planking...
Butt block clamping
I did not have the courage to attempt scarf joints in 1/4" plywood, but I wanted to minimize creating a flat spot in the hull side at the butt joint. So I glued the butt blocks to the side skins with clamps made to the same curvature as the side of the boat. There is a little springback, but I would not increase the curvature without first making a test piece. I did not use any fasteners so as to improve the odds of achieving an acceptable natural finish. (When gluing parts without fasteners sometimes I use alignment pins so parts don't slide around in the wet epoxy. The alignment pins are just 1/8" dowels, and in this case the holes obviously are not drilled completely thru to the outside.)
Bending Foreword Skins
We used Shelman marine plywood which is beautiful stuff, but it does not especially want to bend around the front of a small boat. So, I provided a place to temporarily attach a long lever arm by leaving extra material at the front in areas that would later be cut away. On the sides, extra material is left outside the sheer line and on the foreword bottoms extra material is left outside the stem. Then you can bolt or clamp a long lever arm here. Use a back-up of course and contour the clamping area to match the boat curvature. We then had the means to apply a little persuasion to the plywood with a small block and tackle which gave infinite adjustment.
The Squirt has a bottom now and is awaiting warmer weather for fiberglass. We will first stain the hull mahogany. We learned that one of the best stains to use under epoxy is W.D. Lockwood water soluble dye (wdlockwood.com).
Bill and Linda Whitney, NE Bothell, WA