This page outlines how to repair a hole in a Kevlar kayak hull. This repair process is outlined because the recommended way to repair all types of Kevlar 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
A very sharp razor blade
Vacuum Cleaner
Cleaning alcohol or acetone
Kevlar fabric
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 Kevlar with scissors.

Step 2: Prepare the break for repair:
a) Roughen the edges of the break by sanding the broken area.
b) Sand up to 2 inches (6 centimeters) around the broken area on the surface you will be working on. To repair a hole you will be working on the inside if possible.
c) Be careful not to sand too deep so that you start sanding actual Kevlar. Kevlar "fluffs up" when sanded and becomes hard to work with.
d) If, after sanding, there are fluffy areas of Kevlar, use the very sharp razor blade to get rid of the worst of it.
e) Vacuum the area to be repaired in order to get rid of loose fibers and dirt.
f) Clean the surface around the broken area with alcohol or acetone

Step 3: Cut out the dry Kevlar:
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 Kevlar 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 so the backing will need to match the shape of the outside of your boat. It will be the other way if you don't have room to work on the inside.
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 diagram below for help.



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 smallest piece of Kevlar.
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 Kevlar in epoxy.
c) Wait for the epoxy to slowly saturate the Kevlar to use less epoxy.
d) Encourage the epoxy to soak into the Kevlar by poking it with the tip of the brush.

Step 7: Apply the Kevlar to the hull.
a) Place the layer of fabric, resting on the cardboard backing, over the area to be repaired.
b) Gently smooth out the fabric with the paint brush. Work from the inside of the patch to the outside, coaxing the bubbles to the edge.

Step 8: Repeat step 6 and 7, working from the next smallest piece to largest piece of Kevlar, until you have used all your cut patches. See diagram below.



Step 9: Leave the "backing" on your repair while it dries and spread plastic wrap over 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 10: Once everything has dried you can remove the "backing" and the plastic wrap.
   
Step 11: If you want to, you can gelcoat the outside of the repair for aesthetics. See Gelcoat Repair for instructions. Alternatively you can just paint the repaired area, or leave it as is.


Source: kayakforum.com
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