Epoxy Aluminum Boats: A Step-By-Step Guide To Success

Epoxy is a useful tool for repairing aluminium boats. It can be used to fix leaking seams and rivets, and it can also be used as a barrier coat to provide corrosion protection. When repairing an aluminium boat, it is important to clean and prepare the surface properly, and to follow the instructions for mixing and applying the epoxy. There are a variety of epoxy products available, including those that are specifically designed for use on aluminium boats, such as the TotalBoat Aluminum Boat Leak Sealer and the WEST SYSTEM Aluminum Boat Repair Kit.

How to prepare the surface of an aluminium boat for epoxy

Preparing the surface of an aluminium boat for epoxy is a crucial step to ensure proper adhesion and a long-lasting repair. Here are the steps you need to follow:

Step 1: Clean the Surface

Use a suitable solvent, such as acetone or denatured alcohol, to clean the aluminium surface thoroughly. Remove any dirt, dust, grease, oil, or other contaminants that may be present. This step is essential to ensure that the epoxy adheres properly to the aluminium.

Step 2: Sand the Aluminium

Using 80-grit sandpaper, sand the aluminium surface within a 1-inch radius of the repair area until the metal has a shiny appearance. This process helps create a rough surface for the epoxy to grip onto and also removes any oxidation or corrosion that may be present. Ensure you only sand the immediate area around the repair to avoid unnecessary damage to the aluminium boat.

Step 3: Remove Sanding Residue

Once you have finished sanding, it is crucial to remove any residue left behind. Use a clean, lint-free cloth or brush to wipe away all traces of dust and debris. You can also use a vacuum to ensure that the area is entirely free of any remaining particles.

Step 4: Etch the Aluminium (Optional)

While not always necessary, etching the aluminium surface can further enhance the adhesion of the epoxy. Use a specialised product, such as an aluminium boat etch wash, to clean, condition, brighten, and etch the surface. Follow the instructions on the product carefully, as timing is critical for successful etching.

Step 5: Prepare the Epoxy

Depending on the type of epoxy you have chosen, you may need to mix the resin and hardener according to the manufacturer's instructions. Some epoxies come in a single cartridge, automatically mixing the two components as you apply them with a caulking gun. Others may require manual mixing in the correct ratio.

Step 6: Apply the Epoxy

Follow the instructions provided with your chosen epoxy product for application. Typically, you will use an epoxy spreader or a caulking gun to apply the epoxy to the prepared surface. Ensure you spread the epoxy evenly and thoroughly to cover all the sanded areas.

Step 7: Cure and Sand (if needed)

Allow the epoxy to cure according to the manufacturer's instructions. Depending on the product, you may need to wait several hours or even days before the epoxy is fully cured. Once cured, you can sand the repaired area if needed to smooth out any uneven surfaces.

Step 8: Paint (Optional)

If desired, you can paint over the repaired area to restore the original appearance of your aluminium boat. Ensure that you use a compatible paint designed for use on aluminium surfaces, and follow the manufacturer's instructions for proper application.

How to apply epoxy to an aluminium boat

Applying epoxy to an aluminium boat is a simple process, but one that requires careful preparation. Firstly, it is important to ensure that the boat is clean, dry, and free of any dirt, dust, grease, loose paint, oils, or other contaminants. Sand the aluminium with 80-grit sandpaper within a 1" radius of the leak or repair until the metal is shiny. Be sure to remove any residue from the sanding process before applying the epoxy. For best results, use an aluminium boat etch wash.

Once the surface is prepared, you can begin to apply the epoxy. If using a two-part epoxy, such as the TotalBoat Aluminum Boat Leak Sealer, you will need to mix the resin and hardener together. The TotalBoat Aluminum Boat Leak Sealer comes in a cartridge that fits a standard caulk gun and includes a mixing tip, so you can easily dispense and mix the epoxy directly onto the surface. For other types of epoxy, you may need to mix the resin and hardener separately before application.

When applying the epoxy, use an epoxy spreader to manipulate it and spread it evenly over the prepared surface. The recommended thickness of the epoxy layer is 1/8" to 1/16". Be sure to follow the instructions provided with your chosen epoxy product, as the working time and curing time can vary depending on the product and temperature.

After applying the epoxy, you will need to allow it to cure. The curing time can range from a few hours to a full day, depending on the product and temperature. Once cured, the epoxy can be sanded and painted if desired.

It is important to note that some epoxy products may require additional preparation or priming before application. For example, the TotalBoat Aluminum Boat Barrier Coat Epoxy Primer requires the use of an etch wash to ensure proper adhesion. Always read and follow the instructions provided with your chosen epoxy product to ensure a successful application.

How to repair leaking seams and rivets in an aluminium boat using epoxy

Firstly, you need to identify where the leak is coming from. Fill each side of the boat with water up to the waterline to reduce the risk of causing damage to the boat and distorting its shape. Once the leaking areas have been identified, mark them with a waterproof marker.

Next, turn the boat over and prepare the surfaces around the leaks. For leaking seams, carefully clean out any debris. For leaking rivets, clean the area and use a wire brush to roughen the surface.

Then, create a thoroughly mixed blend of G/flex epoxy resin and hardener in a measuring container, extracting the mix into a syringe. If the repair is large, it may be useful to cut off the tip of the syringe to create a larger opening for ease of application.

Dry out the area for repair by heating it to between 80-100°C using a propane torch or heat gun. This allows moisture to be forced out of the area and thins out the epoxy once applied, ensuring it flows more easily into affected seams and rivets.

Make sure you fill all of the seams and rivets in the heated area whilst the aluminium is still heated. Use a heat gun in one hand whilst applying the epoxy from the syringe with the other.

Once the repair area has a sufficient amount of epoxy applied to it, place the used syringe on a paper towel to catch any excess.

Still using the heat gun, keep applying heat to the treated area until the epoxy has gelled, and then continue at a lower temperature until it’s fully cured, or allow it to cure more slowly at room temperature.

Repeat the process as required for each leak repair area, making sure to maintain sufficient heat throughout. Once the epoxy has completely cured, you can test your boat on the water.

G/flex epoxy creates strong bonds designed to provide unbeatable grip to metals such as aluminium. The bonds are strong enough to endure shocks, knocks, expansion and contraction, meaning that your boat will be fully protected.

How to prevent corrosion on an aluminium boat with an epoxy barrier coat

Aluminium boats are susceptible to corrosion, especially in saltwater and warmer temperatures. Crevice corrosion can form anywhere water can enter but can't exit, such as boat propeller and shaft assemblies. Corrosion can also occur wherever there are junctions that let saltwater enter, such as where objects are attached to the aluminium surface above or below the waterline.

To prevent corrosion on an aluminium boat, you can apply an epoxy barrier coat. Here is a step-by-step guide:

Step 1: Prepare the Aluminium Surface

Start by cleaning the aluminium surface to ensure it is free of any dirt, grease, loose paint, or other contaminants. Use a solvent such as acetone or denatured alcohol to clean the surface. Sand the aluminium with 80-grit sandpaper until the metal is shiny, focusing on the area within a 1" radius of the repair. Remove any residue from sanding before proceeding to the next step.

Step 2: Etch the Aluminium Surface (Optional)

Etching the aluminium surface will provide a better adhesion for the epoxy barrier coat. Use an aluminium boat etch wash to clean, condition, brighten, and etch the surface. Make sure to apply the etch wash according to the manufacturer's instructions. After etching, ensure that you apply the barrier coat within 1 hour to prevent the formation of aluminium oxide, which can hinder the adhesion of the primer.

Step 3: Mix the Epoxy Barrier Coat

Most epoxy barrier coats come in two parts: the base and the curing agent. Refer to the manufacturer's instructions for the correct mix ratio, as slight deviations in the mix ratio can affect the outcome. For example, the TotalBoat Aluminum Boat Barrier Coat has a simple 3:1 mix ratio, meaning you would mix three parts base with one part curing agent. Mix the two parts thoroughly in a paint pot or a separate container.

Step 4: Apply the Epoxy Barrier Coat

The epoxy barrier coat can be applied by brush, roller, or spray equipment, depending on the manufacturer's instructions. Before applying, make sure the aluminium surface is properly prepared and free of any oxidation. Follow the recommended number of coats and dry film thickness specified by the manufacturer. Allow adequate drying time between coats and before launching the boat.

Step 5: Apply Finish Coat (Optional)

The epoxy barrier coat serves as a primer, and you may need to apply a finish coat or antifouling paint, especially for applications below the waterline. Choose a compatible antifouling paint, such as a copper-free option to avoid galvanic corrosion. Follow the manufacturer's instructions for the appropriate drying time before applying the finish coat.

How to fix a leaking aluminium boat with an epoxy leak sealer

Firstly, it's important to identify the exact location of the leaks. Fill your boat with water up to the waterline. If possible, fill one end of the boat and then the other to reduce the risk of causing damage or distorting the shape. Once you have identified the leaks, mark them with a waterproof marker.

Next, flip the boat over and prepare the surface around all leaks. For leaking seams, carefully clean out any debris. For leaking rivets, clean the area and use a wire brush to abrade the surface.

Now, it's time to mix your epoxy resin and hardener in a measuring pot. For this step, you will need to follow the instructions provided with your chosen product. Once mixed, extract the epoxy into a syringe. For larger repairs, you may need to cut the tip of the syringe to create a slightly bigger opening for easier application.

Dry out the area you intend to repair by heating it to 80-100°C using a propane torch or heat gun. This forces moisture out of the area and thins out the epoxy once applied, ensuring it flows more easily into affected seams and rivets.

With the aluminium still warm, fill all seams and rivets in the heated area with epoxy. To maintain the necessary heat and to direct the epoxy into the required areas, use a heat gun in one hand while applying the epoxy with the other.

After applying sufficient epoxy to the area, withdraw the syringe slightly and place it on a paper towel to catch any excess. Keep applying heat to the treated area with the heat gun until the epoxy has gelled. You can then keep applying heat at a lower setting until the epoxy has fully cured, or allow it to cure more slowly at room temperature.

Repeat this process for each area you need to repair, making sure to maintain sufficient heat throughout. Once the epoxy has completely cured, test your boat on the water.

When applied correctly, epoxy leak sealer will not only stop water from getting in but will also protect your aluminium boat for years to come.

Choosing the right epoxy

There are several epoxy leak sealers on the market that are suitable for repairing aluminium boats. These include:

• TotalBoat Aluminum Boat Leak Sealer
• WEST SYSTEM G/flex® 650 Toughened Epoxy
• Marine JB Weld
• Travaco Marine-Tex RM330K Gluvit Waterproof Epoxy Sealer

Frequently asked questions