Fiberglass boats have been popular for recreational use since the mid-1960s because of their great strength and high resistance to corrosion and rust. However, fiberglass can be degraded by the sun and temperature extremes over time. The following steps will show how to build a fiberglass boat.
Build a frame to support the mold. Lay out the pattern and transfer it to the timber framing material by joining the frame pieces with gussets made of half-inch plywood. Screws are the strongest method, but staples are the fastest and most convenient.
Install the mold lining. This is typically plywood or some other suitable sheeting material and is attached to the battens with contact cement. Nails should be used only when absolutely necessary because the heads will be visible in the final laminate.
Apply the laminate when the temperature is between 65 and 80 degrees F. Some type of gelcoat is brushed or sprayed on to the mold's surface at a thickness of no more than a quarter-inch. A clear isothalic gelcoat is ideal, but it must be carefully matched to the resin you will be using to ensure maximum waterproofing.
Put on the first layer of light mat by applying a coating or resin. It is especially important that this layer not have any air bubbles. Apply the required number of mat layers as specified in the plans.
Add additional features such as bulkheads, ribs, stringers and web floors before removing the hull from the mold. You may wish to leave the molding below the water line to serve as a cradle.