TotalBoat Polyester Structural Marine Repair Putty - 1 Gallon | Fiber-Reinforced, Fast-Curing for Hull & Stringer Bonding

TotalBoat Polyester Structural Marine Repair Putty (gallon) is a fiber-reinforced, fast-curing polyester putty formulated for heavy-duty structural bonding and large-volume fiberglass repairs on boats and marine components.

This one-gallon kit combines a thickened polyester resin with long-strand milled glass fiber so you can fill, bond and build up large masses without sagging or excessive shrinkage. It’s designed for jobs that demand strength—bonding stringers, bedding bulkheads, sealing major holes or joining dissimilar materials such as fiberglass to wood or metal. The product ships with MEKP catalyst to start curing; adjusting catalyst volume modifies working time for different temperatures and part sizes.

How do I use this putty for structural bonding?

Mix the putty thoroughly with the supplied MEKP hardener at the recommended ratio and apply to clean, dry substrates. Press or fillet the material into joints or voids; it holds shape while curing so you can build radii and fillets in one pass. After cure, it offers a robust bond suitable for mechanical loads.

• Mix thoroughly and add MEKP (1–2% by weight; 14 drops per ounce ≈ 1% at 70°F).
• Apply to cleaned, abraded surfaces for best adhesion.
• Tool fillets or radii immediately; putty resists sagging in bulk fills.
• Allow full cure before drilling, trimming, or overcoating.

Can I use this putty below the waterline or on gelcoat?

Yes — the polyester structural putty is suitable for repairs above or below the waterline and bonds well to fiberglass and gelcoat. It’s intended for structural filling rather than final cosmetic fairing; for a smooth, paint-ready surface, apply a fine fairing compound over the cured putty before final finishing.

• Works under and above the waterline for structural fixes.
• For a smooth finish, overcoat with a polyester fairing compound once cured.
• To skip an overcoat, add an air-dry agent like paraffin wax or use PVA on the surface.

What materials and repairs is this putty best suited for?

It bonds well to fiberglass, woods, metals and many composite laminates, making it versatile for boatbuilding and general repair. Typical applications include bedding bulkheads, attaching stringers, filling screw holes, repairing hull chips, and uniting dissimilar parts where strength is required.

• Ideal for hull-to-deck bonding, stringer and liner attachment, and bulkhead fillets.
• Fills holes, chips, dents and large voids without shrinking or cracking.
• Also useful in automotive, RV, home or light industrial repairs needing a strong filler.

How long does it take to cure and how do I control work time?

Cure speed depends on catalyst amount and ambient temperature. At about 70°F, a 100 g mass catalyzed at ~1% MEKP gives roughly 15–20 minutes of workable time; increasing or decreasing MEKP changes the working window. Mix only what you can use in that span and follow safety precautions when working with peroxide catalysts.

• Standard guideline: 1% MEKP = ~15–20 minutes working time at 70°F for 100 g mass.
• Adjust MEKP to shorten or lengthen pot life; do small test mixes for unfamiliar conditions.
• Wear proper PPE and work in ventilated areas; dispose of mixed residues safely.

Who is this for? TotalBoat Polyester Structural Marine Repair Putty in the gallon kit is aimed at boatbuilders, professional marine repairers, and serious DIYers who need a rugged, long-strand fiber-filled polyester compound for heavy bonding and bulk filling. If you require a high-strength structural adhesive for fiberglass, wood or metal assemblies—or need to fill large voids quickly without sagging—this product delivers economical, USA-made performance. For cosmetic surfaces, plan to follow with a fairing compound and topcoat for a finished appearance.