Using fiberglass as a skin for the hull of your model boat enables you to create an attractive, yet lightweight, durable and waterproof covering. A hull covered with fiberglass is absolutely smooth, without the grain texture you get from a wooden hull; at the same time, it can be painted with the color scheme of your choice. The fiberglass is only a covering though, and must be placed over an existing hull, such as one of balsa. When laid down properly though, a fiberglass covering can last years, with very little maintenance necessary.
Things You'll Need
- Model boat
- Sanding block
- Bench brush
- Tack rag
- .75 oz. fiberglass cloth
- Cutting board
- Rotary cutter
- Finishing resin
- Mixing cup
- Craft sticks
Construct your model boat according to the instructions provided by the boat kit manufacturer or by the building plans. Leave the hull unfinished when built.
Run the sandpaper over the hull in order to remove any rough areas. Use a fine grain sandpaper for the finish, creating a surface that’s as smooth as possible for the application of the fiberglass cloth. Go over the surface of the hull with a bench brush, removing any sawdust from the hull’s surface. Run a tack rag over the hull, using the wax impregnated in the rag to remove any residue left over from the sanding process.
Cut the fiberglass cloth into strips that are slightly longer than the hull’s length. Use a rotary cutter to cut the cloth. Place the cloth onto a cutting board and then run the circular cutter blade along the cloth. Cut the cloth into strips about two inches wide, so that you can follow the shape of the hull’s curves without leaving any wrinkles in the cloth during the covering process.
Mix a small batch of resin (about a half of a cup) in a plastic cup, according to the manufacturer’s instructions. Use the resin as an adhesive for the cloth, as well as a filler for the small spaces in the cloth, to keep the surface watertight. Wait three minutes for the resin to catalyze.
Brush the seal coat of resin onto the boat hull to seal the wood. Brush lightly, applying a thin even layer of resin to the hull. Allow the resin to cure for 30 minutes.
Lay the fiberglass strips along the hull lengthwise, overlapping about one-eighth of an inch, and slightly overhanging the sides of the hull.
Slowly pour the resin along the cloth, so as to adhere the cloth to the wood. Pour enough resin to spread along the cloth in a thin, even layer. Use craft sticks to spread the resin over the cloth, being careful not to wrinkle or move the cloth in the process. Spread the cloth from the center of the hull towards the edges. If wrinkles occur, use the craft stick to even the cloth before continuing. Spread a slightly thicker layer of resin at the ends of the hull to prevent the cloth from peeling up from the surface of the wood.
Wipe the cloth with a squeegee to remove any excess resin. Avoid creating pools of resin on the cloth to prevent creating an uneven finish. Wait for the resin to cure about 30 minutes after removing the excess resin.
Trim the excess cloth from the ends of the hull and then sand the ends down, making them even with the surface of the hull. Brush a third thin layer of resin, the fill coat, onto the cloth to fill any spaces between fibers in the cloth. Apply only a light layer of the resin. Allow another 30 minutes of curing time.
Place a fourth and final finish coat layer to the hull. The finish layer ensures that there is enough resin to sand the hull smooth, without removing too much cloth in the process. Wait 24 hours for the finish coat to cure completely.
Feather the seams of the fiberglass cloth with the sandpaper, sanding them down until you create a smooth surface. Sand the entire surface of the hull smooth after evening out the seams, until the surface of the hull is smooth to the touch. Wipe the hull with the tack cloth again to remove sanding residue. After sanding the hull smooth, you can prime and paint the model.
Tips & Warnings
- Always wear a particle mask, eye protection, and clothing that covers the entire surface of your skin when sanding fiberglass, for protection from the glass fibers contained in the cloth.
- Only fiberglass your model in a dry environment: A moisture-rich environment interferes with the curing ability of the resin.
- Photo Credit Model boats image by TekinT from Fotolia.com