How to Fix a Crack on a Plastic Kayak

Plastic kayaks can become cracked from any number of causes. Direct and constant exposure to sunlight can cause the plastic to weaken and crack or the kayak may have incurred damage from dragging over rocks. Regardless of the cause, most cracks can be repaired using common power tools and strips of high-density polyethylene (HDPE). The HDPE strips will act as a welding agent to bond the crack closed and seal it off. The amount of HDPE strips you need will be directly proportionate to the size of the crack you are repairing. Purchase enough to cover the crack entirely.

Things You'll Need

  • Power drill
  • 1/4-inch drill bit
  • Screwdriver
  • Sandpaper, 60 grit and 400 grit
  • Heat gun
  • High-density polyethylene (HDPE) strips, colored to match kayak
  • Metal spoon
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Instructions

    • 1

      Drill a 1/4-inch hole into both ends of the crack to create a reinforcement and prevent future spreading of the crack. Wedge a screwdriver into the center of the crack and gently use it to pry the crack open. Open the crack just enough to sand the edges of the crack. Do not force the crack open.

    • 2

      Sand the inside of the crack using 60 grit sandpaper. The roughness created by the sandpaper will serve as a primer for the HDPE. Carefully move the screwdriver as needed but, leave the screwdriver in the crack to continue holding it open.

    • 3

      Heat the crack with a heat gun. Hold the heat gun a safe distance from the crack. Refer to the manufacturer's instructions for your heat gun. Heat the crack until its edges begin to return to the boats original color. Do not heat the crack so that it begins to melt or deform. The crack should only be warm enough so that it is comfortable to touch. Remove the screwdriver.

    • 4

      Hold one end of an HDPE strip and use the heat gun to prep the opposite end. Heat the strip until it becomes flexible and glossy in appearance.

    • 5

      Move the melted end of the HDPE strip to the crack on the kayak. Continue heating the end with the heat gun. Apply slight pressure to the strip to work it into the crack. Hold the heat gun so you heat the HDPE strip and the crack. Spread the melted HDPE strip to blend it into the crack. Do not allow the kayak to burn or melt. It should be just warm enough to blend with the HDPE. Continue blending the HDPE until the entire crack is closed. Allow the HDPE to cool for one hour.

    • 6

      Sand the HDPE weld gently with 60 grit sandpaper to buff out any imperfections. Finish the look by going over the weld with a 400 grit sandpaper until it is smooth and seamless.