Print How to Do Your Own Fiberglass Kayak Repair

by Greg Swenson

So your fiberglass kayak got damaged. Don't be disheartened — the situation probably isn't as bad as you think. There is no fiberglass damage that can't be repaired.

The first thing to do is survey the extent of the damage. Is it superficial or structural, minor or major? Perform a visual inspection inside and outside of your kayak. If you see white stress lines in the fiberglass (inside), it is structurally damaged.

It is possible to get cracks in the gel coat finish without any real structural damage. Most gel coats are polyester based and brittle, but many kayaks (like NC Kayaks) are now manufactured with vinylester resins, which have much more flex than polyester gel coats. So the fiberglass can actually flex more than the gel coat without sustaining any damage.

Once you establish what needs to be repaired, we can determine what needs to done.

For gel coat cracks

• Sand the cracks all the way to the fiberglass.
• Mask off around the area to be repaired with masking tape.
• Gel coat consists of three parts: the gel coat itself, a catalyst, and a surfacing agent to aid in the curing process. The surfacing agent is required for open-air cure of the gel coat. In place of a surfacing agent, you can seal off the repair with wax paper or plastic film. This keeps air out to allow the gel coat to cure completely.
• Apply your gel coat with a brush. Try to apply it as smoothly as possible. This will save you time on sanding after it has cured.
• After the gel coat has cured, it's time for sanding. Start with a 400 grit sandpaper and sand the repair nearly flush. Try not to sand too much around the surrounding areas, as you can sand through that gel coat! You can mask them off to help prevent that. Wet sanding works best. Gradually work to finer grits (600, then 1200) before finally buffing it finished.

For fiberglass repair

• A good rule to follow is for every inch of damage there needs to be 12 inches of repair, a 12-to-1 ratio. If the damage is a puncture, hole, or delamination, remove the damaged area by getting rid of any loose material. If the damage is only stress lines you can simply repair over them.
• If you are using the woven roving, one ply each of mat and roving is usually sufficient. If you are using cloth you will need two plies of cloth and one ply 1½ ounce mat.
• Prepare the fiberglass by cutting some mat to fit and fill the hole. Also cut some the size of the repair 12-to-1 ratio. Cut the cloth or roving just slightly bigger than the mat.
• Rough up the area to be repaired with sandpaper — 120-220 grit is preferred — this aids in bonding.
• Clean the area to be repaired with acetone. This removes any contaminants and also reactivates the existing resin to help with adhesion.
• Back up the existing hole on the outside of the boat with cardboard coated liberally with wax or plastic film. This helps to keep the proper shape of the kayak exterior.
• You are now ready to laminate. Mix your resin and catalyst per manufacturer's instructions.
• Install the mat in the hole. Wet out the mat and the entire repair area with the resin using a brush.
• Add the first ply of mat. Apply more resin to the mat. Roll with a small paint roller or fiberglass roller to remove any trapped air.
• Add the next ply, cloth or roving and apply more resin. Lightly squeegee to remove any trapped air. Apply subsequent plies following the same procedure.
• After the resin cures, sand any rough edges.
• Now it's time to repair the gel coat using the process above.

Materials

• Resin. Please note which type of resin you choose to use. Epoxies bond to everything, but polyester and vinylester resins will not adhere to epoxies. Try to use the same type of resin the kayak was made from (vinylester for NC Kayaks).
• Catalyst. The resin you purchase will generally have a recommended list of catalysts, most commonly an MEKP.
• Gel coat. Trying to match color can be frustrating. UV rays can fade colors over the years, and even "white" may not look the same from manufacturer to manufacturer. Our advice is to try to be as close as possible, but accept that it probably won't be perfect.
• Surfacing agent or wax paper / plastic film.
• Acetone. This is commonly sold as nail polish remover, but that often has artificial coloring and odors added.
• 1-2" paint brush, depending on the size of the repair.
• 1½ ounce fiberglass mat.
• Either 6-ounce fiberglass cloth or 18-ounce fiberglass woven roving. The roving will build up thickness quicker than cloth. The 6-ounce will give a cleaner looking repair. Either will give a strong finished product.
• Small paint or fiberglass roller.
• Plastic squeegee.
• Sandpaper in various grits.
• Buffing compound.

Warnings / Tips

• Find a warm dry environment. Sixty-five degrees is the minimum temperature you should attempt to do a repair in. But the higher the temperature the shorter your work time is.
• Wear appropriate safety equipment, especially disposable gloves. Resin and gel coat are impossible to remove from clothing once cured. They can surely hurt your skin too. A paper towel with acetone — while it will dry your skin — will help remove drops.
• Mask, mask, mask! You can save yourself a lot of headache by preventing drips, overzealous sanding, and errant brushing from causing problems by masking off nearby areas.

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