Short answer
You can seal leaking rivets and seams in an aluminium boat yourself with a tough epoxy that tolerates hull movement, such as West System G/flex. Smaller holes and tears are repaired with glass cloth and the same epoxy on both sides. Loose rivets, long cracks and damage to structural parts need new rivets or welding, which is a job for a workshop.
Find the leak
- Put the boat on stands or a trailer and pour some water into it. Mark where it drips out with a marker pen.
- Drain the boat and let it dry completely.
- Turn the boat over if you can. It is easier to work with the seams facing up, but the repair also works with the boat upright.
Sealing rivets and seams
- Sand or wire brush along the seam and around the rivets until you see bright metal.
- Mix G/flex 650 in equal parts resin and hardener and fill a syringe.
- Heat a 30–45 cm section of the seam with a heat gun. Epoxyworks also describes a propane torch, but heat carefully.
- Lay a bead of epoxy along the seam and around the rivet heads. The heat thins the epoxy so it wicks in between the plates.
- Gaps and loose rivets: thicken the epoxy to a mayonnaise consistency and press it in until it comes out the other side.
- Wipe off excess. Let it cure overnight at a minimum of 18 °C before using the boat.
Heat shortens the pot life. Stop heating if the epoxy discolours or starts to smoke.
Repairing a crack or hole
West System describes a repair for damage up to 15 × 15 cm:
- Tap the metal back as close to its original shape as possible. Cut away torn edges.
- Drill a small hole at each end of the crack so it does not grow.
- Sand with 80-grit paper and remove all paint at least 5 cm around the damage, inside and out.
- Wet out a piece of glass cloth, 5 cm larger than the hole on all sides, with G/flex and lay it on the outside.
- Fill gaps from the inside with thickened epoxy and apply cloth there too.
- Sand once the epoxy has cured, then paint.
Epoxy, rivets or welding?
| Damage | Best fix |
|---|---|
| Weeping rivets, dripping seams | Epoxy (G/flex or similar) |
| Loose rivets that move | New rivets, ideally combined with epoxy |
| Small tear or hole up to about 15 × 15 cm | Fibreglass and epoxy |
| Long crack, crack in keel or transom | Workshop: welding or new plate |
| Welded boat with a crack in the weld | Workshop that can weld aluminium |
Keep in mind
- Do not use copper-based antifouling directly on aluminium. Ask the paint manufacturer about paint for aluminium, and read the rules on antifouling.
- Replace worn-out sacrificial anodes so the hull does not corrode.
- Silicone and ordinary sealant rarely hold in a riveted seam that moves.
Safety
Epoxy can cause allergies. Wear nitrile gloves and safety glasses. Use a heat gun rather than an open flame near fuel and solvents. Don't breathe in sanding dust from paint and metal, so wear a respirator.
Frequently asked questions
Can I seal rivets with silicone?
It can stop the leak for a short while, but silicone bonds poorly and lets go when the hull flexes. A tough epoxy that wicks into the joint lasts longer.
Can you weld a riveted boat?
It's possible, but the heat can warp the plate and damage nearby riveted joints. Have a workshop that welds aluminium assess it.
How do I know if a rivet is loose?
It moves or spins when you press it, and there's often grey oxide powder around the rivet head. Loose rivets should be replaced.