Fiberglass Boat Core Repair
Water intrusion into a fiberglass boat can eventually cause rotted plywood or damaged core material hidden between fiberglass skins. Repairing the problem requires more than simply stopping the leakāthe deteriorated core must be identified, removed and replaced while preserving or rebuilding the surrounding fiberglass structure. The project below demonstrate practical fiberglass core repair techniques, including removing water-damaged plywood, fitting replacement core materials such as Coosa Board, bonding with epoxy, fiberglass reinforcement, fairing and finishing the repaired structure.
Fiberglass core repair is a fundamental boat restoration skill. Develop it early and practice it often for success.
Water intrusion around windows, portholes, deck hardware and other penetrations can eventually cause the core inside a fiberglass boat to rot or delaminate. Once the core loses its integrity, simply resealing the leak won’t restore the strength of the surrounding structure. Recurring leaks can therefore be an indication of a structural problem rather than just failed sealant.
A proper fiberglass core repair involves removing deteriorated material until solid structure is reached, installing new core material, bonding it with epoxy and reinforcing the repair with fiberglass. Replacement materials can include plywood, traditional foam cores or structural composites such as Coosa Board, depending on the application.
This project shows how I rebuilt deteriorated cored structure surrounding the portholes of an older fiberglass boat. The complete repair process, materials and lessons learned are covered in the MotorCity Boat Werks Technical Library.
The complete step-by-step process is available in the MotorCity Boat Werks Technical Library. Watch the video below for detailed project steps and solutions.
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