The sides were made out 2 sheets of 1/2″ marine plywood bought from Dysons lumber. One sheet was ripped to provide two equal 20″ x 8′ pieces. The other sheet was cut at an angle to provide two long side 28″ and shorts side 20″ pieces (both 8′ long).
These sheets were brought together and an epoxied butt joint was made, using an 8″ wide butt strap to provide strength at the joint. Important: the butt strap wasn’t taken all the way to the bottom edge because room needed to be made for the chine in addition to approx 2″ spiling. Spiling is the bottom curvature due to wrapping a straight surface to a curved surface (picture trying to wrap masking tape on the bottom half of a softball).
Layout of the Plywood Pieces
The butt strap was made from the 8″ wide “leftover” after ripping the two 20″ width pieces. Allotting for roughly 2″ spiling plus 3″ chine height, the butt strap was cut 15″ (or 20-5)” and the outside surface was routed with a 1/2″ round over bit. Both pieces of plywood were place near to each other, epoxy applied to the ends, and both pieces were pushed together. The butt strap area was wet-out, West Systems silica thickened epoxy applied, and the butt strap positioned in place (and allowed to fully cure).
The sides were lifted up on the boat for dry fit. The important thing to look for is to make sure the plywood will cover the entire surface due to spiling, after all clamps and such are put into place. The stern was secured by using a regular old ratchet strap. The stem was just a little more complicated as a wedge had to be temporarily attached so the clamps can be used without sliding off the stem.
The dry fit should produce reference marks that will be used to properly place sides when glue is applied (so as not to make a glue mess with multiple adjustments). After the dry fit was completed (we actually did 2 dry fits to be sure of what we were doing), we applied a liberal amount of PL Premium to all facing (mating) surfaces and smoothed it with a putty knife. The sides were lifted and the aft side was placed against the transom. A washered screw was placed at the highest and lowest place at the transom. We used washered screws because we initially wanted max “pull” without running through the plywood, with the goal of remove and replace with standard stainless deck screws after the glue dried. These washered screws were simply a black drywall screw with a standard #8 washer installed. While someone held the stem end of the plywood, the other person would install washered screws (at chine level) moving from back to front. We avoided the temptation of putting a screw at the transom, then the stem, to make holding the plywood easier, but that method would likely result in a gap at the chine. Once all the chine screws were put in place, and good glue squeeze out noticed, we moved to countersink drilling then installing #8 1-1/4″ stainless screws along the ribs, trying to provide 4″ spacing between screws. After all the screws were installed, we scraped excess glue off the joints, then cleaned up the joints with mineral spirits. After the glue dried, the washered screws were removed and replaced #8 1″ stainless screws.
After the glue dried, the sheer cut was prepared and marked. Since the boat is sitting normal (i.e. not upside down) the first thing to do is mark where the bottom is, as there is still the spiling overhanging. Simply get a small piece of wood and go behind the spiling and mark its depth. This is important because significant error can be introduced if sheer line measurements are taken from edge of the plywood (vs the projected bottom of the boat). After the bottom was marked, and double checked, the sheer line points were marked to the dimensions presented in the Scantlings page. A 16′ batten was selected from excess material (chine I believe). The batten was then attached to the side (with clamps) so the top edge of the batten ran through all the sheer line points. Then we took a Sharpie and ran that sheer line through the length of the boat. The batten was remove and a circular saw was set to full depth as we want the ribs cut at the same time. Then the saw was carefully ran from the stern and stopping slightly before the stem. The bit of plywood attached to the stem was carefully cut with a handsaw because we didn’t want the stem cut down to the sheer. We want a little stem sticking up so it looks like a “Bay” boat. Then a handsaw was used to remove the excess plywood in front of the stem and behind the transom (then smoothed with a orbital sander). At this state, the side is complete except for bottom which still needs to be trimmed flush due to spilling.
Closer Look of Batten