What materials do I need for a fiberglass boat repair?

Materials Needed for a Fiberglass Boat Repair

The materials needed for a fiberglass boat repair depend on the type and extent of the damage, the original construction of the boat, and whether the repaired area will be finished with gelcoat or marine paint.

A small cosmetic repair may only require grinding, filling, sanding and refinishing. Structural damage, holes, cracks, delamination, soft decks, damaged stringers or a deteriorated transom may require new fiberglass reinforcement and replacement core material.

Common Fiberglass Boat-Repair Materials

• Safety equipment: Safety glasses, chemical-resistant gloves, protective clothing and a suitable respirator.
• Grinding and sanding abrasives: Grinding discs and sandpaper for removing damaged fiberglass, tapering the repair and preparing the surface.
• Resin: Polyester, vinyl ester or epoxy resin selected for compatibility with the existing laminate and repair requirements.
• Fiberglass reinforcement: Fiberglass cloth, chopped strand mat, biaxial fiberglass, woven roving or fiberglass tape.
• Core material: Coosa Board, Divinycell or another marine core material when the original transom, deck, stringer or panel core is damaged.
• Bonding and structural fillers: Milled fibers, thickened resin or a structural adhesive for bonding core materials, filling gaps and creating fillets.
• Fairing compound: A sandable fairing material used to smooth the repair before applying gelcoat, primer or paint.
• Finish materials: Gelcoat, epoxy primer, marine topcoat or another finish compatible with the repair system.
• Application tools: Mixing cups, graduated containers, brushes, spreaders, fiberglass rollers and laminating rollers.

Cosmetic vs. Structural Fiberglass Repairs

Cosmetic damage generally includes gelcoat scratches, chips, small gouges and shallow surface cracks that do not affect the strength of the laminate. These repairs may only require surface preparation, filling, sanding and refinishing.

Structural damage includes holes, fractured laminate, widespread cracking, delamination, damaged stringers, soft decks and deteriorated transoms. These repairs normally require the damaged fiberglass or core to be removed and rebuilt with compatible resin and reinforcement.

Choosing the Correct Resin and Fiberglass

Polyester resin is commonly used for repairs to conventionally built fiberglass boats and works well with chopped strand mat. Vinyl ester resin provides improved water and chemical resistance and is often selected for demanding marine repairs. Epoxy resin provides strong adhesion and is useful for many structural repairs, but compatibility with chopped strand mat, gelcoat and the final coating system must be considered.

The fiberglass reinforcement should be selected according to the strength, thickness and shape required. Fiberglass cloth is useful for controlled laminate thickness and smoother finishes, while biaxial fiberglass provides strength in multiple directions. Chopped strand mat helps build thickness and creates a resin-rich bonding layer when used with a compatible polyester or vinyl ester system.

Information Needed Before Selecting Materials

Before purchasing repair materials, identify:

• The length, width and depth of the damaged area
• Whether the damage is cosmetic or structural
• Whether the area contains plywood, Coosa Board or foam core
• The type of resin or coating already on the boat
• Whether the repair is above or below the waterline
• Whether the final finish will be gelcoat or marine paint
• Whether the repair can be accessed from one side or both sides

Get Help Selecting a Complete Repair System

Fiberglass Florida can help you select the resin, fiberglass reinforcement, core material, fillers, abrasives and finishing products needed for your boat repair. For the most accurate recommendation, provide clear photographs, measurements, the location of the damage and details about the existing surface.

Visit our Rockledge location in Brevard County or our Stuart location in Martin County for help with fiberglass boat-repair materials. Fiberglass Florida also ships fiberglass, resin, gelcoat, core materials and repair supplies throughout the United States.

Important: Repairs involving extensive structural damage, hull integrity, engine mounting areas or major transom failure may require evaluation by a qualified marine-repair professional.