This page outlines how to repair a hole in a carbon fiber kayak hull. This repair process is outlined because the recommended way to repair all types of carbon fiber damage (whether already a hole or merely cracks or chips) is to cut away the damaged material and repair the resulting hole.

If the damage you want to repair is a crack or chip and you don't want to cut away the damaged material, the instructions below can be adapted for performing a "patch" repair, rather than a "hole" repair. Specific instructions for doing this are not covered on this website, however, because it creates an inferior repair.

If you have a damaged boat, before you start repairing you should ensure you know exactly what material it is made from (click here for details) and you should make sure you have assessed the damage to decide which type of repair to do. (click here for details).

Materials:
Scissors
Sandpaper
Vacuum Cleaner
Cleaning alcohol or acetone
Carbon fiber cloth
Sturdy cardboard
Plastic wrap (cling wrap)
Duct Tape
Epoxy Resin
Disposable paint brush

Step 1: Clean up the break:
a) Cut away any jagged or damaged sections of carbon fiber using scissors.

Step 2: Prepare the break for repair:
a) Roughen the edges of the break by sanding the damaged area
b) Sand up to 2 inches (6 centimeters) around the damage on the surface you will be working on. To repair a hole you will be working on the inside if possible.
c) Vacuum the area to get rid of loose fibers and dirt.
d) Clean the surface around the broken area with alcohol or acetone

Step 3: Cut out the dry carbon fiber:
a) You need to cut out enough layers to make your repair the same thickness as the boat (usually about 3 or 4 layers).
b) Cut out one patch the size of the hole and the others progressively larger. The largest should be about 2 inches (6 centimeters) wider than the hole.

Step 4: Create a backing for the repair:
This backing will provide the surface to hold the carbon fiber in place while you repair.
a) Cut a piece of cardboard about 3 inches (7.5 centimeters) larger than the hole.
b) Bend it to the shape of the missing hull area.
c) If possible you will be repairing from the inside of your kayak so the backing will need to match the shape of the outside of your boat.
d) Cover the cardboard in plastic wrap. This will allow the backing to lift away from the repair when dry.
e) Tape the backing securely over the hole. If you are working from the inside (which is better) tape it to the outside and vice versa if you have to work from the outside. See image below:



Step 5: Mix the epoxy according to the manufacturer's instructions.
Make sure you don't mix too much. It dries fairly quickly and you don't need a huge amount.

Step 6: Wet out the carbon fiber.
a) Work on a disposable surface like an old piece of wood or a piece of cardboard.
b) Use the paint brush to soak the carbon fiber in epoxy.
c) Wait for the epoxy to slowly saturate the carbon fiber to use less epoxy.
d) Encourage the epoxy to soak into the carbon fiber by poking it with the tip of the brush.

Step 7: Apply the carbon fiber to the hull, starting with the smallest piece that is the size of the hole and moving to the largest piece.
a) Place the each layer of fabric one at a time on the area to be repaired. See diagram below.
b) Gently smooth out each layer with the brush. Work from the inside of the patch to the outside, coaxing the bubbles to the edge.



Step 8: Spread plastic wrap over the finished repair and leave it to dry. Leave the "backing" on the other side.
This is done to help create a smooth surface once it is dry and to help avoid nasty fibers sticking out of the repaired area.

Step 9: Once everything has dried you can remove the "backing" and the plastic wrap and sand the outside for smoothness.
   
Step 10: If you want to, you can gelcoat the outside of the repair for aesthetics. See Gelcoat Repair for instructions.


Source: kayakforum.com
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