Trade Secrets: Repairing Minor Cracks & Holes in a Fibreglass Boat

Ever seen those pesky cracks or scratches on your fibreglass boat? Most of the time, they’re just cosmetic, but they can really annoy you. Thankfully, epoxy’s a lifesaver! WEST SYSTEM® Epoxy can be used for creating a super strong, waterproof fibreglass repair that’s perfect for fixing those surface dings.

In this section, we’ll tackle how to patch up minor cracks and scratches, and even reinforce areas that might be prone to cracking. Let’s get your boat looking at its best again!

Assessing damage

It’s easy to spot scrapes, scratches, and cracks caused by impacts, but figuring out why other cracks or crazing might appear can be trickier. Most of these cracks happen due to flexing and are often found in areas with solid laminate. You might find them near a bulkhead, deck to cabin curve, or window.

Besides fixing the cosmetic damage, you might need to do some structural repairs or add reinforcement to stop the flexing. The longer the laminate keeps bending or the harder the impact, the deeper the cracks. This results in weakened panels.

Before starting the repair, let’s take a closer look at the damage:

Looking at the pattern and location of the cracks to figure out what’s causing them. If it’s flexing, look inside the boat to find the best spot for extra reinforcement. If it’s from an impact, check inside to see if the damage goes all the way through the laminate.

Open up the cracks. Use a sharp “V”-shaped tool to scrape down to the bottom of the cracks. A can opener with a sharpened tip works well for this. Bevelling the sides of the crack gives the repair more surface to stick to. If you have a lot of closely spaced or deep cracks, it might be easier to grind out the whole area. Scrape or grind as deep as needed to reach solid, undamaged material.

Repairing Minor Cracks & Holes

For minor cracks affecting only the gelcoat layer:

Clean the area thoroughly. You want a clean surface so the repair will stick well.
Mask off the area around the crack. This will protect the surrounding gelcoat from getting sanded or scratched. Sand the crack lightly with 80-grit sandpaper to roughen it up for better bonding.
Mix a small amount of gel coat and catalyst according to the manufacturer’s instructions. Apply it with a clean brush, filling the crack and making sure it’s a bit higher than the surface.
Let the gelcoat cure completely (usually 24 hours).
Sand the area smooth with wet and dry sandpaper. Start with 220 grit and move finer (380, 600, and 1000 grit) for a perfect finish.
Buff and polish the repaired area to match the surrounding gelcoat. You might need to polish the entire section if the colour has faded over time.

If The Crack Is Deeper

Remove any wax, oil, or mould release from the area using a solvent. Make sure it’s dry before proceeding.
Carefully scrape out the crack with a V-shaped scraper to create a clean surface for the gelcoat to bond to. Don’t go through the gelcoat!
Follow steps 3-6 from the previous instructions to fill, cure, sand, buff, and polish the repair.

Minor Crack & Abrasion Repair

Do you have a small crack or scrape that’s reached the chopped strand mat layers of your laminate? No worries! WEST SYSTEM Epoxy can fix that.

How To Repair:

Prep the Area: Use a “V” shaped scraper to dig out the damaged area. Feather the edges with the scraper or sandpaper and clean up any dust or loose stuff.

Wet the Cracks: Soak the cracks with a resin/hardener mix.

Fill the Cracks: Thicken the resin/hardener mix with 404 High Density Filler or 406 Colloidal Silica Filler until it’s about as thick as peanut butter. Fill the cracks with the thickened epoxy, smoothing it out with a mixing stick or squeegee. Let it cure completely.

Sand and Finish: Sand the area with 100-grit sandpaper to remove any bumps or ridges. Then, wet-sand it with 220-grit. Finish with gelcoat or paint.

How Bad is The Damage?

Before selecting a finish, it’s crucial to accurately assess the extent of the damage.

Small Repairs: These typically involve scratches, dings, or minor chips.

Large Repairs: This includes significant damage, such as gouges, cracks, or holes.

Deeper Damage: This involves damage that extends below the gelcoat layer, potentially reaching the fibreglass or wooden core.

Choosing the Ideal Finish?

For small repairs polyester gelcoat is a popular choice for small repairs due to its ease of application and durability. It’s often available in various colours to match your boat’s existing finish.

However, for large repairs polyurethane paint is known for its exceptional durability and resistance to fading, this paint is ideal for larger repairs. It offers a long-lasting, high-quality finish.

If your repair happens to be below the waterline then WEST SYSTEM Epoxy is a primary resolution. It provides a strong, water-resistant barrier that prevents moisture from penetrating the hull. Once cured, it can be sanded and primed before applying antifouling paint.

For deeper damage, a more comprehensive repair process may be necessary. This often involves carefully removing the damaged section of the hull, sanding and cleaning the exposed area to ensure proper adhesion and reinforcing the damaged area with either fibreglass or wood depending on the hull material. To seal the repaired area and provide a strong, watertight bond, WEST SYSTEM Epoxy should be applied. Finally, the repaired area can be finished by applying gelcoat or paint to match the surrounding area.

Additional Considerations

When selecting a finish, it’s important to consider both environmental factors and the boat’s intended use. For example, a UV-resistant finish may be necessary in areas exposed to harsh sunlight to prevent fading and degradation. Additionally, the boat’s intended use will influence the choice of finish. For instance, a boat used for racing may require a lightweight, low-drag finish to improve performance.

Are you a boat owner looking to tackle a GRP repair? Check out the WEST SYSTEM Fibreglass Boat Repair Kit!