Balsa with a 23- Final Preparation Before Painting

top of the radio compartment. You can use the piece cut out of the radio-box lip as the radio-box top or as a tem- plate to cut one out of plastic. Cut out the front I/z-inch balsa bulkhead brace and glue it into the hull. Attach 1/4x1/8-inch spruce strips to the inside top lip of the hull sides, and use binder clips to hold them in place while the glue cures. After the glue has cured, sand the strips to the contour of the sides. Coat the inside of the hull entirely with 2-hour epoxy, then add a second coat the next day. Aftet 72 hours, spray expandable foam into both sides of the huil at the transom and in the bow. The foam will act remove the engine and drill a hole Binder clips hold the spruce strips in as flotation if the model overturns at the pond. Add in the bulkhead with a 1.9164 drill placeandmakebuildingeasy' iust a little at a time because the expandable foam usu- bit where the drive shaft will pass ally expands much more than you would expect. through the radio-box bulkhead. Mark the transom for the drive- Cut the deck out of 7s-inch plywood, and add t/$ls-inchr shaft hole by measuring up the centerline 7e inch from the bot- spruce support stdps to its underside. Coat the entire underside tom and the inchl to the right. This drive-shaft offset will compen- with 3O-minute epoxy and run a thick bead of epoxy along the sate for engine torque. Bend the drive-shaft tube by hand to make spruce strips at the upper rim of the hull where it joins the deck. it fit from the engine through the radio-box bulkhead and Use masking tape to hold the deck in place and maintain a slight through the transom, where it will become the strut. Install the overhang. The overhang will be sanded flush with the hull sides tube later so that it won't interfere with sanding and painting. after the glue has cured. Do not glue the deck to the ftont bulk- Sand the spruce stlips on the outside edge of the hull so that head; there should be a l/z-inch space between the bulkhead and you can install the hull halves. Cut the hull sides out of 7:z-inch the deck. pl1'wood and install them. Glue the sides to the bottom so that they stay at the same angle from the transom going forward. The FINISHING sides will follow a natural flow from the transom to the bow, so Sand the entire hull don't glue them to the two balsa bulkheads. with 150-grit sand- Chances are that you sanded the sides of the balsa bulkheads paper; round off too much when you sanded the spruce strips; this is OK because the edges at the top you'll have to glue small pieces of plywood between the bulk- but leave the edges heads and the sides to support them without bending the sides sharp at the tran- Use auto-body putty to fill the gap where out of shape. The bottom edges of the side pieces will overhang som so the water the sr'des overhang the bottom of the hull. where they meet the hull bottom. Fill this area with auto-body will part there. Seal The overhang provides a strong joint and putty to strengthen the joint and form the spray rail. the huil by coating acfs as a useful spray rail. If necessary, add small pieces of spruce to make the sides flow it with slow-curing smoothly to the tip of the bow then, with a sanding block, sand epoxy. With a plastic squeegee, scrape off excess epoxy so that the the top of the boat to ensure a smooth line from the transom to hull remains light and requires only minimum sanding. The light the bow coat of epoxy will seal most of the hull, but you may need to Cut tlvo radio-box apply auto-body putty to a few places to smooth sides out of l/z-inch any imperfections. Use 150-grit sandpaper as the balsa with a 23- final preparation before painting. Three coats of degree bevel cut on primer and three coats of paint, and you are ready the bottom edge, and for hardware installation. also cut olt a rcat Y2- inch block that will HARDWARE INSTALLATION be mounted on the I used a variety of hardware. My engine mount is transom between the homemade, but a standard 4-inch rubber-isolated two radio-box sides. engine mount can be used. The rudder should have

Glue them all into -!l place with the out- side edges of the sides 6r/z inches The hardware apart. Cut a 6Vzx7- setup is prew 3/sz-inch inch piece of much a plywood to form the standard outer lip f or the surfece-drive radio-box lid. Cut configuration, but the strut is away the middle, as offset slightly shown on the plan. to the right to GIue the radio box's help control outside rim lip to the torque roll.

ocT0BER 2000 35