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Do not use the template I posted. My hull arrived today and I’m going to revise it slightly. My hole came out oversized (easy to fix), and I will re-do it in a day or two. Using the revised template, mark and cut out the stuffing tube hole in the tunnel floor. Mark the deck opening as shown in the photograph and cut it out. Keep the scrap for future use. NOTE: It is important that the “lip” that remains in the hatch opening be as small as practical. 1/8” is adequate. If this lip is too big, the upper deck will not fit properly on the center bulkhead, and you will have problems installing the batteries and accessing equipment. Sometimes Randy’s hulls need some final trimming. If you look closely, you can see a trim line in the plastic. Mark this with a Sharpie pen and trim to that line (sorry for the blurry photo, but you get the idea).
After the cutting has been completed on the hull and deck, perform a test-fit on the framework. Adjust the stuffing tube hole if necessary. Don’t worry if it gets a little too large, the tunnel floor reinforcement will help fill any gaps. Since the corners of the hull are somewhat rounded, some sanding may be necessary on the framework edges and corners to get a good fit, especially at the bottom of the transom/stringer joint. Add a small piece of triangular stock to the stringer/transom joint to strengthen this area.
Inspect the area where the turn fin will attach. Glue the turn fin doublers (2 each) to the bulkhead. Depending on how things fit, you may want to glue the doublers on one side of the bulkhead or the other, so that you have a good contact with the hull at that point. See photo. I did one on each side. Attach the rudder doubler to the transom as shown in the photo (I’ll post this photo later). Once you are satisfied with the fit of the frame, paint the entire framework with thin epoxy. The slower setting the epoxy, the better. I use a 4:1 mix epoxy with the “fast” (8-hour) hardener from Diversified Materials in La Mesa, California. You can order this from their website.
Using some medium-grade sandpaper, roughen up the inside of the tunnel floor and clean with denatured alcohol. Spray a very light mist of 3M-77 glue on the tunnel floor. I mask off this area and spray the glue into the air a few feet above the hull, allowing just a fine mist to fall on the tunnel floor. You are not using this glue to attach the fabric; rather, it is just to make it tacky and keep the fabric from moving around as you apply the epoxy and framework. Cut out some fiberglass cloth or carbon fiber mat so that it goes from the transom to the front of the tunnel, and extends past the sides of the tunnel floor by about ¼” or so (1/2” to ¾” in the sponson area is acceptable). Carefully place the reinforcement on the tunnel floor and smooth it down into place, being careful to avoid wrinkles or fraying the edges. Cut a slit in the fabric for the stuffing tube.
Using a small paintbrush, apply some thin epoxy onto the fabric with a paint brush, again being careful to avoid wrinkles and/or fraying. You only want to wet-out the fabric, not have pools of epoxy on the floor. Then, use a paper towel to blot-up the excess epoxy. This helps stick the fabric to the floor and soak up excess epoxy (weight). Run a small bead of expanding polyurethane glue on the forward underside of the front cross-member. While the epoxy on the tunnel floor is still wet, insert the framework, and use clamps, weights, tape, or a strategically placed drop of CA (in the sponson bottoms) to hold things in place while the epoxy goes off. Exercise care to guarantee the hull is “square” as the epoxy goes off. When the epoxy has cured, go back and fill any small gaps in the framework/hull joint with epoxy. Big gaps can be filled with thickened epoxy or expanding polyurethane glue. Be certain you have a good joint at the turn fin doubler. Fill the gap between the framework transom and the hull transom with thickened epoxy or polyurethane glue. Pay close attention to the rudder area. You want this as solid as possible. Fill any gaps in the tunnel floor/stuffing tube joint with thickened epoxy.
After the cutting has been completed on the hull and deck, perform a test-fit on the framework. Adjust the stuffing tube hole if necessary. Don’t worry if it gets a little too large, the tunnel floor reinforcement will help fill any gaps. Since the corners of the hull are somewhat rounded, some sanding may be necessary on the framework edges and corners to get a good fit, especially at the bottom of the transom/stringer joint. Add a small piece of triangular stock to the stringer/transom joint to strengthen this area.
Inspect the area where the turn fin will attach. Glue the turn fin doublers (2 each) to the bulkhead. Depending on how things fit, you may want to glue the doublers on one side of the bulkhead or the other, so that you have a good contact with the hull at that point. See photo. I did one on each side. Attach the rudder doubler to the transom as shown in the photo (I’ll post this photo later). Once you are satisfied with the fit of the frame, paint the entire framework with thin epoxy. The slower setting the epoxy, the better. I use a 4:1 mix epoxy with the “fast” (8-hour) hardener from Diversified Materials in La Mesa, California. You can order this from their website.
Using some medium-grade sandpaper, roughen up the inside of the tunnel floor and clean with denatured alcohol. Spray a very light mist of 3M-77 glue on the tunnel floor. I mask off this area and spray the glue into the air a few feet above the hull, allowing just a fine mist to fall on the tunnel floor. You are not using this glue to attach the fabric; rather, it is just to make it tacky and keep the fabric from moving around as you apply the epoxy and framework. Cut out some fiberglass cloth or carbon fiber mat so that it goes from the transom to the front of the tunnel, and extends past the sides of the tunnel floor by about ¼” or so (1/2” to ¾” in the sponson area is acceptable). Carefully place the reinforcement on the tunnel floor and smooth it down into place, being careful to avoid wrinkles or fraying the edges. Cut a slit in the fabric for the stuffing tube.
Using a small paintbrush, apply some thin epoxy onto the fabric with a paint brush, again being careful to avoid wrinkles and/or fraying. You only want to wet-out the fabric, not have pools of epoxy on the floor. Then, use a paper towel to blot-up the excess epoxy. This helps stick the fabric to the floor and soak up excess epoxy (weight). Run a small bead of expanding polyurethane glue on the forward underside of the front cross-member. While the epoxy on the tunnel floor is still wet, insert the framework, and use clamps, weights, tape, or a strategically placed drop of CA (in the sponson bottoms) to hold things in place while the epoxy goes off. Exercise care to guarantee the hull is “square” as the epoxy goes off. When the epoxy has cured, go back and fill any small gaps in the framework/hull joint with epoxy. Big gaps can be filled with thickened epoxy or expanding polyurethane glue. Be certain you have a good joint at the turn fin doubler. Fill the gap between the framework transom and the hull transom with thickened epoxy or polyurethane glue. Pay close attention to the rudder area. You want this as solid as possible. Fill any gaps in the tunnel floor/stuffing tube joint with thickened epoxy.
That small weight savings may be offset by painting it.
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