Step 3: Hull and Frame Assembly

Review: The most critical factor is to add the rocker distance to each station rib.  In other words station number 6 and 7 will be highest when it is upside-down, as they are the actual lowest point in the boat when it is sitting upright.  Be sure your frame is level!  Once you have positioned the station-ribs and the two bulkheads, it is time to screw down the bottom, sides, transom and stern piece.  These are temporary screws, which will be removed later.  Once the framework is covered, the next step is to epoxy all of the seams first with 2-inch cloth followed by a second layer of 4-inch cloth.  Always brush on a coat of epoxy to new wood and let it set up for twenty minutes; otherwise the cloth may not stick well as the resin is pulled deeper into the wood.  Remove temporary screws.  After the seams have been reinforced, cover the entire outside of the boat with 6-ounce fiberglass cloth and epoxy resin. (See Devlin's book for excellent instructions.)

When the resin has cured, detach the base frame and flip over the boat.  Applying an epoxy-filler, fillet the joints inside the boat just around the two bulkheads, the transom and the stern plate.  When the resin fillet material has cured, epoxy the seams with fiberglass cloth and resin just as you did to the outside seams.  Finish the inside of the boat with a layer of 6-ounce cloth and epoxy-resin. Since I used 1/4-inch plywood for the sides, I fiberglassed the inside all the way up to the chime. If you used 3/8-inch plywood for your sides and covered the outside, you would not need to cover the inside except for the seam. Encapsulating the plywood does add extra weight.

Filleting Material for the Inside Joints: The reason for using a resin grout to fill the seams is so that you may apply the fiberglass cloth without the glass strips blistering.  The resin grout also contributes to the strength of the boat.  Fill the seams with just enough material to provide a rounded curve.  Spread this material with a plastic spreader, which you may purchase at automotive parts store.  The easiest mixture to make for a joint compound is to mix the epoxy with wood flour, which is fine wood dust collected from the bags of wood sanders.  Mix the thickness of the filleting material to the consistency of creamy peanut butter.  Keep returning to check for sagging or dripping.  (Most of the epoxy manufacturers sell powdered filleting material.)

Steps for Building the Bitterroot Pram