Repairing Aluminum Boats: Fixing The Rear Damage

Aluminium boats are simple to repair and replace, as aluminium does not break like fibreglass. However, they can still be damaged by hard-grounding or colliding with other objects, which may result in cracked rivets and leaks. To repair the rear of an aluminium boat, you can use a specialised aluminium boat repair kit, which typically includes epoxy glue, aluminium scrap metal, and a stainless steel brush.

How to repair a damaged rear of an aluminum boat

Fixing a crack in the hull with epoxy

To fix a crack in the hull of an aluminum boat with epoxy, follow these steps:

Step 1: Prepare the Hull

First, restore the hull to its original shape by hammering out the torn aluminum. You can cut away torn edges to help the aluminum lie flat and, to reduce the chance of further cracking, drill stopper holes at the end of each tear. Then, soften the edges of the aluminum with 120-grit sandpaper and use a coarse bristle disc to remove paint from both sides of the crack, creating a sound bonding surface.

Step 2: Create the Patch

Cut a piece of Episize™ glass fabric for the outside of the hull and three pieces for the inside. Allow for a 2-inch overlap around the crack to give your materials space to bond. Brush both sides of the crack with the epoxy, working it into the scratches and dings. You can use a thickened mixture of colloidal silica with the residual adhesive to fill any small holes and cutaways around the repair.

Step 3: Apply the Patch

Lay the pieces of fabric on plastic and wet them with the epoxy. Apply the single patch for the outside of the hull first, smoothing it into the thickened mixture. Then, stack and apply the three inner patches, using a squeegee to ensure no air is trapped, and center them over the crack on the inside. Once the stack of patches is in place, lightly squeegee over the area again to remove any remaining air.

Step 4: Finish the Patch

Leave the patches to cure overnight. The following day, remove any roughness from the edges of the patches by grinding them. Finally, apply a mixture of epoxy and low-density filler to the patches inside and out. Once the fairing mixture has cured, your boat is ready to be tested on the water!

Repairing a hole with epoxy

Repairing a hole in an aluminium boat using epoxy is a straightforward process, but it does require some preparation and the right tools. Here is a detailed, step-by-step guide on how to repair a hole with epoxy in an aluminium boat:

Step 1: Shape and Clean the Metal

Get the hull back to its original shape by hammering out the torn aluminium gently. You can use an auto-body or bucking dolly for this step. If necessary, cut away any torn edges to help the aluminium lie flat. To reduce the chance of further cracking, drill small stopper holes at the end of each tear. Softening the edges of the tear with 120-grit sandpaper, and use a coarse bristle disc to remove paint from both inside and outside the hull. This creates a good bonding surface area. Finish by abrading the surface with 80-grit sandpaper.

Step 2: Prepare the Patch

Cut a single piece of Episize Glass Fabric for the outside of the hull and three pieces in diminishing sizes for the inside. The outer patch and the largest inner patch should be about 2 inches larger than the hole to allow for overlap and bonding.

Step 3: Apply Epoxy

Brush both surfaces of the canoe with a suitable epoxy, such as G/flex 650, working the adhesive into scratches and dings. Mix the epoxy with colloidal silica to create a thickened mixture to fill any small holes or gaps.

Step 4: Apply the Patches

Apply the single patch to the outside of the hull first, smoothing it into the thickened epoxy mixture. Stack the three inner patches together, ensuring no air is trapped, and centre them over the hole on the inside of the hull. Carefully lay the stack into place and gently squeegee over the area to remove any air. Check that the outer patch is not being pushed out of place, and adjust if necessary. Leave the patches to cure overnight.

Step 5: Finish the Repair

The next day, use a grinder to smooth the edges of the patches and remove any roughness. Apply a mixture of G/flex and low-density filler to fair the patches, smoothing the outside for better hydrodynamics and the inside for cleanliness and scuff resistance. Once cured, apply a mix of G/flex and grey pigment to camouflage the repair. Your boat is now ready to test on the water!

This method of repairing a hole with epoxy in an aluminium boat is a simple and effective way to restore the original function and aesthetics of your boat, and it will ensure your boat is ready for many more adventures.

Using a special aluminium boat repair kit

A special aluminium boat repair kit is a great option for fixing your boat as it is a fast and inexpensive method for repairing leaking rivets, cracks, and small holes. The kit typically includes easy-to-follow instructions, epoxy resin and hardener, mixing tools, protective gloves, and cleaning pads. Some kits may also include additional items such as syringes, mixing cups, and a stainless steel brush for surface preparation.

• Prepare the Work Area: Read the instructions provided in your repair kit carefully. Gather all the necessary tools and materials and lay them out within easy reach. Ensure you are in a well-ventilated area and wear protective gear, including gloves and eye protection.
• Assess the Damage: Inspect the damaged area of your boat thoroughly. Determine the size and extent of the cracks, holes, or leaks that need to be repaired. This will help you estimate the amount of material needed and the number of repairs you can make with your kit.
• Clean and Prepare the Surface: Use a stainless steel brush or sandpaper to clean and roughen the surface around the damage. This step is crucial as it ensures the epoxy will adhere properly to the aluminium surface. Remove any dirt, grease, or debris from the area to be repaired. You can use alcohol or acetone cleaning pads for this purpose.
• Mix the Epoxy: Following the instructions and the provided mixing ratio, carefully measure and mix the epoxy resin and hardener. Most kits use a 1:1 mixing ratio. Use the provided mixing sticks and cups to combine the two components thoroughly. You may need to wear gloves during this process to protect your skin.
• Apply the Epoxy: Once the epoxy is mixed, apply it directly to the damaged area. If you are repairing a hole, apply the epoxy to the underside of the hole and use it as a trough for a brazen rod to settle into. You can also use aluminium scrap sheets or strips to cover the hole and bond them using the epoxy.
• Fill and Smooth: After applying the epoxy, use a brazen rod or additional aluminium material to fill in any cracks, holes, or gaps. Ensure the filler material is secure and level with the surrounding surface. Use a flat file to grind away any excess material that extends beyond the repair area. Smooth the repaired area with sandpaper to create a uniform surface.
• Cure and Finish: Allow the epoxy to cure completely according to the manufacturer's instructions. This may take several hours or a couple of days, depending on the product and the temperature. Once cured, inspect the repair and ensure it is strong and watertight. You can repaint the repaired area or the entire boat for added protection and aesthetics.

By following these steps and using a special aluminium boat repair kit, you can effectively repair leaking seams, rivets, cracks, and small holes in your aluminium boat. Remember to work in a safe and well-ventilated area, and always follow the specific instructions provided with your chosen repair kit.

Welding or riveting an aluminium patch

Step 1: Assess the Damage

Before beginning any repairs, it is important to assess the extent of the damage. This includes measuring the size of the hole or crack and determining whether there is any underlying structural damage. If the damage is limited to a small area, a patch can be an effective repair method.

Step 2: Prepare the Surface

Clean the damaged area with acetone and rags to remove any dirt, grease, or debris. Ensure the surface is dry and free of any contaminants that may interfere with the repair process. This step is crucial for ensuring a strong bond between the patch and the boat's surface.

Step 3: Cut the Patch

Using the measurements from Step 1, cut an aluminium patch that is slightly larger than the damaged area. The patch should be made of a similar thickness and type of aluminium as the boat's hull. This ensures that the patch has a similar strength and flexibility to the surrounding material.

Step 4: Position the Patch

Place the patch over the damaged area, ensuring that it overlaps the surrounding surface by at least 1 inch. You may need to drill holes along the edges of the patch to match the holes in the boat's hull for riveting. If welding, ensure that you have access to the backside of the hull and that there are no flammable materials nearby.

Step 5: Weld or Rivet the Patch

If welding, use a suitable welding machine and aluminium welding rods. Weld along the edges of the patch, ensuring complete penetration and a strong bond. If riveting, insert rivets through the holes and secure them with a rivet gun. Ensure that the rivets are tight and flush with the surface.

Step 6: Finish and Seal

Once the patch is securely welded or riveted, finish the repair by sealing any gaps or seams with a suitable marine sealant or epoxy. This will help prevent water ingress and ensure the longevity of the repair. Allow the sealant to cure according to the manufacturer's instructions before returning the boat to the water.

It is important to note that welding aluminium requires more specialised skills and equipment than riveting. Aluminium has a low melting point, and overheating can easily occur, resulting in warping or destruction of the metal. Therefore, if you are not confident in your welding abilities, it may be best to opt for riveting or seek the assistance of a professional welder.

Sealing with Marine-Tex putty

Sealing with Marine-Tex Epoxy Putty is a great option for repairing your aluminium boat. Marine-Tex is a high-strength repair compound designed for filling, bonding and rebuilding various materials, including metal. It is manufactured to meet the harsh demands of marine environments, so it's an excellent choice for repairing areas below the waterline.

Marine-Tex is a two-part epoxy putty with a creamy paste consistency that can easily fill gaps and be shaped to rebuild damaged components. It provides waterproof repairs and can be used with fibreglass tape to reinforce structural repairs. It can also be used to permanently bond dissimilar metals without causing galvanic corrosion, making it ideal for aluminium boats.

Step 1: Surface Preparation

Before starting, ensure the temperature of your work area is at least 55°F (13°C) and maintain this temperature for 24 hours while the epoxy cures. Clean the damaged area of your boat with acetone or a lacquer thinner to remove any dirt, oil, or grease. Sand the area and remove the grit to improve adhesion.

Step 2: Mixing the Epoxy

Store the Marine-Tex at 70°F (21°C) for ease of mixing and application. The mixing ratio is critical: mix 5 parts epoxy resin to 1 part hardener by volume. You can also mix by weight, in which case the ratio is 6.3 parts resin to 1 part hardener. Mix the components on a broad, flat surface using a putty stick or hard plastic squeegee. Only mix enough for 15-20 minutes of working time.

Step 3: Applying the Putty

Marine-Tex can be applied to vertical or horizontal surfaces. Spread the mixed epoxy into a long, thin line to ensure a streak-free consistency and maximise your working time. Apply the putty to the damaged area, filling gaps and shaping it as needed. You can use a putty knife with a small amount of water to smooth the surface for a cleaner finish.

Step 4: Curing and Sanding

Marine-Tex has a cure time of 24 hours at a constant temperature of 72°F (22°C). Lower temperatures will result in longer cure times. Once cured, you can sand or grind the repaired area to shape, tap and drill it, and finish it with most common paints and coatings.

Safety Precautions

Always work in a well-ventilated area when using Marine-Tex. Avoid contact with skin and eyes. Be sure to wear rubber or vinyl gloves and eye protection. Wash your hands immediately after use.

Frequently asked questions