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Building
The Independence
Building a Stitch and glue plywood model sailboat.
Introduction Making the hull Installing the radio gear Making the Keel Rigging and sails
The plans show full size templates for cutting the panels which make up the hull. Start by tracing the patterns onto the plywood
Use a nail, prick punch or ice pick to trace the pattern by punching through the paper template. Mark along the lines every 1-2 inches. Also mark the location of wire holes 3/8" away from the edge of the panel along the station lines.
Remove the paper template from the plywood. Use a long straightedge and a pencil to mark the edges of the panels. Try to layout the panels on the plywood to use it efficiently. Cut the right and left side panels from separate sheets of plywood.
Put clamps on the two stacks of plywood to secure them as you cut. Make sure the two sheets in each stack are aligned. The clamps will hold the two pieces in place as you saw to make two identical pieces of each.
Saw out the pieces slightly outside the lines. Clamp the pieces together as you cut them out. Be sure to support both the plywood and the pieces you cut out (including scrap) so that the pieces don't move. I use a bench top jig saw to cut the panels, you can also use a utility knife, coping saw, band saw or saber saw (hand held jig saw.) Be sure to use a sharp, fine blade to avoid splintering the wood.
Use your block plane to smooth the edges and adjust them to the marked lines.
Drill 1/16" holes where you marked for them on the station lines plus one half way between 1/2" from the edge of the panels. Also, drill holes 1/2" from the end of the hull panels 1-2" apart.
Cut the transom pieces too. Cut a "bulkhead" from the plywood using the 7th station from the bow in the end or section view as a guide. Draw the bulkhead full size on the plywood or a piece of paper. Copy the 7th station and mirror it to get the full width of the boat. Draw a line inside that line offset by the thickness of the plywood. The bulkhead is smaller than the 7th station by the thickness of the plywood. I cut two big holes in the bulkhead to provide access into the bow of the boat and to lighten it. I left the center section to help support the keel and deck.
After unclamping the panels, bevel the edges so they make a neat joint with their mates. They should be beveled to an angle half of that at which the panels meet. The bottom panel should be beveled a lot where the keel is deeply "V"ed near the ends and less toward the middle. I found that a bit too much bevel was OK and allowed the panels to join tightly. Bevel all the panels with thought to the angles at which they meet their neighbors.
In preparation for the next step make dozens of 2"- 3" lengths of wire to use for stitching the panels together. I use 24 gage copper wire.
First loosely wire together the two bottom panels along the center line and up the bow. Stack the two panels with the good sides facing each other so the holes line up and pass the wire through and loosely twist the ends together with your fingers.
Next, wire in the bulkhead and transom to spread the bottom panels. Then, wire on the chine panels then the sides. Finally add the sloping transom. All the wires should still be only moderately tight, so, twist them tight while checking that every thing is aligned properly. Make sure the boat is not twisted. When tightening the wires, you may need pliers to twist them tight, but only tighten them enough so that the panels meet snugly. Over tightening the wire can break the wire or rip the panels at the hole.
Check that all the joints in the hull are tight and that the panels meet cleanly. Make sure that the lines of the boat are fair…look for humps and valleys in along the joints. You may need to un-wire a section and take a stroke or two with your block plane for humps. Or you can loosen the wires and insert a toothpick or similar bit of wood into the joint to raise valleys.
At this point the hull has taken its final shape and can be stabilized with epoxy. Brush some epoxy into the inside of the hull along the joints where the panels meet. You can also use a syringe to squirt a bead of thickened epoxy into the joints. If you avoid getting epoxy on the wires, you can remove them prior to filleting and taping the joints.
Wait until the epoxy is cured before proceeding to the next step.
Cut or untwist the wires holding the deck onto the hull.
Cut a scrap piece of plywood into an epoxy spreading tool 1-1/2" wide, 8" long with a rounded end. Sand the edges smooth.
Press the wires into the inside of the joint with a screwdriver. This is so the wires can be hidden under the epoxy fillet. Alternately, the wires can be removed as long as the epoxy you spread in the previous step will hold the joint. Removing the wires can make a neater job.
Brush epoxy to wet out the plywood around all the joints.
Mix epoxy with wood flour to a peanut butter consistency. Mix batches of 2-4 ounces as needed. Bigger batches may cure before you finish, especially in hot weather.
Spread the epoxy into the joints with a tongue depressor, Popsicle stick or plastic spoon to make a fillet. Remember to fillet the bulkheads to the bottom and sides. Try to be neat, making an even fillet with no lumps along the edges. Where two panels meet at a shallow angle you can use a plastic squeegee to create a smooth transition between the panels. The ends of the hull are a little tricky and require the most epoxy. Use fairly thick epoxy mixture there so that the fillet stays put.
Cut fiberglass cloth the length of each joint 1" wide and lay it onto its joint. Brush unthickened epoxy on to the tape. Use the plastic squeegee and bristle brush to help move the epoxy around. Try to get only enough epoxy on the tape to thoroughly wet it out, (so it is clear) not so much that it drips. Squeegee excess epoxy onto the plywood to seal it. Seal the entire interior of the boat including the bulkheads.
First cut all the (remaining) wires using flush cutting wire-cutters. You will have to pull some of the wires up out of the epoxy in places before cutting. You can also use a soldering iron to heat the wires breaking the epoxy bond so that you can pull them out.
Sand the surface to smooth the wires and drips. You should use a sanding block with medium (80 grit) sand paper to smooth the entire boat. Sand carefully, do not over do it and sand through the first layer of the plywood. Try to get all the drips off. Round over the joints slightly with your sandpaper
Glue a strip of wood around the inside of the sides to support the deck. Glue it below the top edge of the sides so that the deck will be flush with the sides when you add it later.
I often use a sheet of sandpaper folded in half to hand sand the boat, almost as fast as a power tool. I spray the back side or the sandpaper with contact cement first, then fold it in half. The contact cement keeps the two sides from sliding against each other and makes the paper stronger and easier to use. Try it.
After planing out the deck opening, I glued several cross beams between the deck support strips previously glued to the sides. I built a frame around the deck opening to stiffen the deck. I also reinforced the places that would hold the rigging.
I cut the deck to fit into the hull and around the mast and keel boxes. I also cut out the deck opening.
I dry fitted it to make sure it fit well, then sealed the inside with epoxy and glued it in place with thickened epoxy. I filled any joints that needed it, at the same time.
I drilled a hole to accept the rudder tube and epoxied the tube in place.
Then I sealed the entire boat with epoxy, sanded it and painted it.
Updated on February 2, 2010
by Shearwater Boats
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