Repairing holes in aluminum canoes can be a challenging endeavor at first glance. Due to the thinness of the metal, it is difficult for the amateur welder to fix and often requires the talents of a professional TIG welder. If the hole is small enough, a common fix is to plug the hole with a bolt, washer and nut, then cover the entire assembly with a waterproof resin. Assuming you're faced with a large gash and no friends in the welding business, a bit of elbow grease and modern chemistry can have your canoe patched and back on the water in short order.
Patching the hole
Step 1
Drill small holes at the edges of any tears to prevent them from becoming any larger and use tin snips to remove any sharp points on the corners of the tears. Then, use a hammer to reform the torn metal back into the original curve. You won't make it perfect, but get it as close as you can.
Step 2
Use 120-grit sandpaper to remove any paint around the tear, inside and outside of the canoe. This will also roughen the surface area of the surrounding metal to ensure a stronger bond with the patch.
Step 3
Cut a piece of patching material, typically a piece of fiberglass cloth such as 745 (12 oz.) Episize glass fabric, so there will be a two-inch overlap over the hole. This patch will go on the outside of the canoe. Cut three more pieces, of decreasing size, to be applied to the inside of the canoe. Make the first layer have a 2-inch overlap over the hole, with the second and third layers slightly smaller than the fabric beneath it.
Step 4
Lay each patch on a piece of plastic and thoroughly wet it with a specialized aluminum repair epoxy such as G/flex 650. Also brush the epoxy on inside and outside surfaces of the canoe.
Step 5
Apply the outside patch first, centering it over the tear and smoothing it into the epoxy already on the canoe. Stack the three interior patches, largest on the bottom and smallest on the top, then squeegee them to remove any trapped air. Center the stack over the hole on the inside of the canoe and lay it in place.
Step 6
Check the outside of the canoe to make sure the pressure from applying the inside patches did not push the outer patch out of shape. Gently reposition any patches as necessary and let them cure overnight.
Step 7
Sand the patch edges to remove any roughness. Apply another coating of G/flex and a low density filler, such as West System's 407, to smooth any rough spots in the patch. Allow to cure.
Step 8
Mix G/flex and with gray pigment and apply to the outside patch to help hide the repair.
Tips and Warnings
- Patience is critical to reshaping metal. Don't try and pound the torn metal back to its original shape with one blow of the hammer. It is tempting to adjust and re-adjust the patch and artfully sculpt the resin. Let the material do its job and you can finesses the shape and surface during the sanding process.
- Make sure to work in a well ventilated area. Allow the resin to fully harden, or cure, per the manufacturer's directions, before sanding.
References
- Boatbuilding.net: Patch Holes in Aluminum Boats with G/flex Epoxy
- "The Outboard Boater's Handbook: Advanced Seamanship and Practical Skills"; David R. Getchell; 1994
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