How to Repair a Pontoon With Foam

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The foam used to repair a pontoon boat leak comes in the form of a liquid. Once released from its canister, the foam expands and can easily fill the pontoon, eliminating any space for water to enter. Foam released into the cavity of the pontoon provides maximum buoyancy. You will save money by running your pontoon boat at maximum buoyancy, starting with greater fuel efficiency, as fuel consumption will decrease.

Items you will need

  • Cork

  • Power drill

  • Drill bits

  • Clear vinyl tubing

  • Water-resistant silicone sealant

  • Vacuum

  • Fine-grade sandpaper

  • Epoxy sealant

  • Alcohol

  • No-sand primer

  • Anti-fouling fiberglass paint

Determine how much water has seeped into the pontoon cavity. Obtain a container that will hold this amount of water. It is important to remove all the water in the pontoon cavity before releasing foam into the empty space.

Purchase a cork and clear vinyl tubing to siphon the water in the pontoon cavity. Drill a hole through the cork the same size as the vinyl tubing and pull the tubing about 7 inches through the cork.

Seal each side of the cork where the tube protrudes with water-resistant silicone sealant. Allow the sealant to dry.

Insert the longer end of the tubing into the opening port at the top of the pontoon. Insert the tube until it hits the bottom of the pontoon cavity.

Mark the tube so that the depth of the pontoon cavity is visible when vacuuming out the water inside the cavity. Using a vacuum eliminates the risk of the pontoon collapsing, since air enters the hull and prevents a vacuum from developing in the pontoon cavity.

Level the pontoon boat to extract the most water using the vacuum. All pontoons collect water through condensation, but excess water is a sign that a puncture has occurred.

Prepare the pontoon for release of the foam into the cavity by cleaning the area around the leak with an alcohol solution. Alcohol will evaporate and leave the area around the leak dry.

Rub the area with a cloth and find the hole in the exterior of the pontoon. Feel for a rough edge in the smooth surface of the exterior pontoon.

Size up the hole found and insert the thin straw attached to the foam canister. Release the foam into the pontoon cavity according to the directions.

Wipe the surface area of the hole with a clean cloth to remove any residual foam on the exterior.

Rub the smooth area with fine-grade sandpaper to roughen the surface and ready it for the epoxy sealer.

Shake the epoxy sealer with the cap closed until it becomes a rollable consistency. Drag the brush end of the epoxy cover over the hole. Cover the area thoroughly and let dry.

Turn the fine-grade sandpaper over to the unused side after the epoxy is dry and rough it up slightly without removing the sealer. Cover the area with a no-sand primer and allow the maximum time for the primer to dry.

Determine if you want to cover up the repair or if the metal is in acceptable condition as is. If painting, use anti-fouling fiberglass paint and allow it to dry according to the directions for the maximum length of time.


  • Remove as much water as possible before spraying in the foam to receive the maximum level of buoyancy.
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