DIY Johnboat

Construct the upper frame, or top rail, and the bottom frame, or keel rail, from pieces of 2-inch-by-3-foot PVC pipe. Use a tape measure and reciprocating saw to make the cuts. Make the 12-foot-long top rail using four 3-foot pieces for its length and two 3-foot pieces for its width. Make the keel rail using three pieces to a side and two pieces wide. Connect them together with T-connectors pointing down, from the top rail, and up, from the keel rail, at the 3-foot intersections. The top should have 90-degree elbows at the corners connecting to the bow and stern tubes and four T-connectors. Use PVC adhesive to glue all the connections.

Make the bottom using four 3-foot sections with T-connectors, the T pointing up and the front, or forward, corners ending in a bidirectional joint. Accomplish this by inserting a 1-inch piece of 2-inch PVC pipe into the forward end of the most forward T-connector. Then take a 90-degree elbow, heat it with a torch and stretch it open to 135 degrees. Slide this elbow onto the 1-inch extension piece of 2-inch PVC pipe and point it up. The 43-1/4-foot section that will extend up from this joint will be attached to the most forward corner of the top rail. This creates the johnboat's bow. Make this same multipiece corner design on the front corners of the top rail, pointing down to receive the bow pieces.

Measure, cut and insert twelve 24-inch pieces of 2-inch PVC pipe into the corresponding T-connections on the top rail and the keel rail, to connect the top rail and keel rails together. Measure and cut two 43-1/4-inch pieces of 2-inch PVC pipe to connect the front corners of the keel to the top rails.

Measure and cut nine 3-foot pieces of 2-inch PVC pipe. Connect them with T-connectors to form the keel interior frame, measuring 9-by-6 feet. This frame is three pieces long, and two pieces -- T-connected left and right -- wide.

Turn the skeleton over on a pair of sawhorses, and make detailed measurements of the sides, keel, bow and stern. Measure and cut 1/2-inch plywood that matches those dimensions. Exact measurements will vary due to T-connection inexactness. Lay the cut plywood pieces up against the exterior sides of the skeleton, and tape the seams temporarily with duct tape.

Invert the boat, and attach the interior pipes to the plywood with a two-step operation. Drive construction nails 2-1/2 inches long through the center of the PVC pipe and into the plywood. Do this every 12 inches around the entire interior of the PVC skeleton. Pull out all the nails and drive 2-1/2-inch wood screws through all the nail holes and into the plywood. Invert the boat and pull off the duct tape.

Mix 1/2 gallon of epoxy resin and hardener (2-1 ratio) in a wooden or metal bucket. Use a roller to paint the entire outer surface of the boat with the epoxy mixture, and wait one hour. Cut and lay sheets of fiberglass fabric, which are the same dimensions as the plywood pieces cut for the skin of the boat, onto the epoxied surface. Be sure that the dominant weave pattern of the fiberglass fabric is parallel to the long axis of the keel. Use a fiberglass-quality roller to thoroughly wet the surface of the fiberglass fabric. Wait one hour and apply 3-inch-by-3-inch fiberglass tape to all the seams. Cut the excess edges of fabric, and roll an additional layer of resin over all the seams. Age the fiberglass for 24 hours.

Use a lacquer thinner and cheesecloth to clean the oxidized blush from the surface of the tape. Use a roller to apply the next coat of resin. Apply two more layers of fiberglass fabric, being sure to wet the top layer. Allow the boat to cure for seven days. Clean the surface with lacquer thinner, and apply two coats of marine-grade paint to the outer surface of the boat.