Fiberglass Repair for Boats
Fiberglass’ repairability is one of its best characteristics and for boat owners, this is good news. Fiberglass is simply layers of glass fabric saturated with polyester (or epoxy) resin. The most unsuspecting scratch or damage in a fiberglass hull can be quickly repaired with a bit of glass fabric, a supply of resin, and some care and skill. In doing so, the repair can look like a new piece of skin that is indistinguishable from what it was previously.
Damage from impact nearly always results in some delamination. To begin repairing the damage, the impact area will be diagnosed often by gently tapping the impact area with a plastic tool to determine the severity of the damage because solid laminate sounds sharp while delamination dull. The next step would be to make a circular or oval cut to carefully remove the damaged area. Damaged fiberglass cannot be salvaged and should be properly disposed, and replaced with new laminate.
If the damage is small enough and above the waterline, repair from inside the hull is possible. This way, the repair from the inside allows you to support the hole on the outside with a polished surface, creating a mold that also allows a lay-up of the repair in a similar way the boat was built.
The area around the hole is thoroughly washed with a dewaxing solvent. Failing to remove the wax first will cause it to wedge into the scratches and weaken the bond when grinding as grinding is the key to getting a precision repair. And no matter how strong the laminate-to-laminate bond is, the initial bond of any repair is mechanical, not chemical, so careful grinding is essential.
After the dust is wiped with an acetone-dampened rag, the sanded surface the exterior surface of the skin around the hole will be given a heavy coat of paste wax.
Often a piece of smooth plastic laminate or thin clear acrylic a foot larger than the hole will be cut and used for the repair along with sufficient cut fiberglass fabric that fits the size of the damage.
For above-the-waterline repairs, either polyester or vinylester resin can be used. For even stronger repair, epoxy can be used, but not if the surface of the repair will be gelcoat. Epoxy is mainly used for underwater repairs. If polyester or vinylester resin are used for the repair, laminating resin is also used. The catalyst for both polyester and vinylester resin is methyl ethyl ketone peroxide (MEKP). Note: MEKP is not the same as the solvent MEK.
Trained professionals will follow manufacturer guidelines to keep the boat in top condition upon repair. The temperature, weather, and thickness of the laminate can all affect curing times. Hardening can take up to two hours, so scheduling in advance of use is best. The gelcoat used is essentially pigmented polyester resin. When the gelcoat kicks after spraying it, a polyester resin is used to lay-up the first two layers of mat and one layer of cloth, compressing them together against the gelcoat and working them out smoothly with a resin roller.
For a finished look, a rectangular piece of mat is cut along with a similar sized piece of cloth to apply over the patch and then smoothing them with a squeegee. This top layer is sealed with plastic or polyvinyl alcohol (PVA), which is a water soluble synthetic polymer, to allow a full cure. Imperfections are filled in the new gelcoat with gelcoat paste and allowed to fully cure. The area around the patch is cleaned before sanding (if necessary), and then polished. While some boat owners gather peace of mind tacking this on their own, you have the option to let the professionals do the job worry-free, so call today!