How to Lay Fiberglass on a Transom
The transom on a boat, or aft or back section, holds the motor in place with a thick laminated core of wood, or in some cases, multiple layers of thick marine plywood. The transom takes more stress than any part of the boat, since it deals with the constant weight and torque of the engine. The transom can also be one of the wettest parts of the boat, frequently taking in water over the top rail. Laying new fiberglass on a transom takes time, skill, some basic tools and the right types of products to perform the task.
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Things You'll Need
- Plastic sheet
- Epoxy filler putty
- Putty knife
- Orbital sander
- Fiberglass cleaner-degreaser
- Scrub brush
- Bucket
- Sanding pads (400 grit)
- Felt pen
- Scissors
- Fiberglass mat (12 ounce or larger)
- Push pins
- Masking tape
- Resin
- Plastic container
- Paint roller pan
- Foam paint rollers
- Squeegee
- Utility knife
- Sanding block
Instructions
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Choose a moderately warm day to perform the fiberglass task. Work outside under a car port if possible. Make sure you have removed the engine and motor mount bracket from the transom, along with any rub rail, cleats or mounted hardware. Place a plastic sheet on the ground underneath the transom. Mix a solution of fiberglass cleaner-degreaser in a bucket and scrub the transom down, removing all wax, oil and foreign matter. Rinse with water.
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Use epoxy filler and a putty knife to fill in any deep gouges or cracks in the old gel coat or fiberglass mat. Paste the filler in hard, and smooth it out with the putty knife. Let it dry according to directions.appears rotted.
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Use an orbital sander with a 400 grit sanding pad to sand the entire transom area, overlapping the edges and hull bottom by about four inches. Sand past the gel coat and into the fiberglass, if the fiberglass appears rotted.
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Wipe the transom down with fiberglass cleaner-degreaser and a rag. Dry buff with rags. Place a large enough sheet of fiberglass over the transom to cover it completely. Use push pins and masking tape to hold it in place. Make sure you have overlap on all sides. Use a felt pen to draw an outline of the transom on the fiberglass. Cut the fiberglass outline with scissors, and lay the fiberglass pattern aside.
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Stir a batch of epoxy resin in a plastic container, according to directions. Measure the correct amount of hardener in a mixing cup and add it to the resin. Stir the contents. Mix enough to make one pass over the transom. Pour the resin mixture into a roller pan. Use a sponge roller to roll a light coat of resin over the transom surface. Use up and down strokes with firm pressure. Overlap the edges about four inches. Let it dry for six hours.
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Mix a second batch of resin and hardener in a container, as you did before. Use a new sponge roller to roll a heavy coat of resin over the transom surface, overlapping at least four inches. Wait a few minutes for it to get tacky. Mix a third batch of resin and hardener and set it aside.
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Place your fiberglass pattern onto the transom, starting at the top and laying it down to the bottom. Align it squarely. Use masking tape around the edges and top to keep it from falling or sliding. Pour your third batch of resin in a paint roller pan. Use a new sponge roller to roll resin into the fiberglass, starting in the middle and fanning your way out to the edges. Roll a thick coat.
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Take a squeegee and start at the middle of the transom and push the excess resin out toward the edges. Use the scissors to cut small diagonal slits in the joint seams of the fiberglass, so it will lay over and adhere around the edge corners. Use the end of the squeegee to lay the corners and seams down. Let the resin dry, according to directions or at least dry to the touch. Mix a fourth batch of resin, identical to the last ingredients.
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Use a new sponge roller to apply the final finish coat. Make it a thick coat, since it will be the gel coat on top of the fiberglass surface mat. Let the fiberglass dry and cure for least 24 hours, or according to directions. Use a utility knife to cut the outline for the bilge hole. Use the sanding block to sand the fiberglass mat edges at the joints, sides and bottom of the hull where it overlapped.
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Tips & Warnings
Before assembling your motor, bracket and hardware on the transom, consider if you will be painting the transom to match the rest of the boat color scheme. Only light sanding is required before adding one or two coats of marine epoxy hull paint.
References
- Photo Credit Thomas Northcut/Photodisc/Getty Images
