Plastic Kayak Welding 101
Whitewater kayaking is a sport that deals with nature and its elements. Unfortunately for us kayakers, our gear is nowhere near as strong as the elements of the river. If you are boating frequently or in unfriendly river beds, there is a good chance you will end up cracking the hull of your kayak. We are building a series of quick step-by-step guides to get your leaky boat sealed up and back on the water.
Here is installment 1 on plastic boat repair w/ video.
- Heat Gun
- Razor/SHARP Knife
- Drill Bit
- (Optional) Small Sheet of Rubber or synthetic material that won’t melt.
- (Optional) Bituthene patch
Get plastic. One of the more popular places to pull excess plastic from is the inside of the cockpit rim. Use your razor to shave a small shim of plastic free (the shim should be comparable to the size of the crack).
Drill a hole that is only a small amount wider than the crack at either end. This will stop the spreading of the crack.
Welding plastic follows the same idea as welding metal. Using the heat gun, you need to get both the boat and your shim of plastic really hot so they bond together, instead of just melting the shim on top of the boat which will just eventually flake off. Once both the shim and the area around your crack are sufficiently hot you will notice the plastic is shiny and almost wet looking. Carefully hold the shim with pliers then start placing the shim into the crack. Make sure to completely fill the crack and use your knife to spread excess plastic around the crack for adequate bonding. Note: You will need to keep using the heat gun to keep things warm enough. This is a two-handed process that takes A LOT of practice to get right.
Be CAREFUL- When heating the area around the crack, be aware that the area around the crack might start to rise into a mound. If this is happening it means you are heating the area too much or just simply getting the boat too hot. Try to stay focused on the area in question.
Once you feel you have sufficiently filled the crack with plastic and have even coverage, use your rubber sheet to make your plastic flat and smooth. While keeping the patched plastic hot with the heat gun, press the rubber sheet down on top of the patch. CAREFUL- Plastic will be HOT! Repeat this process until you’ve reached a satisfactory final product. Make sure there are no rough edges that can get caught on rocks and rip off.
Step 5 (Optional):
For a bomber final step, Bituthene (a type of tar tape) can be used to ensure maximum dryness. Locate the crack on the inside of your hull, and cut a patch a few inches larger than the dimensions of the crack. Pull off the tape backing and lay the Bituthene sticky side down. Use the heat gun to warm the Bituthene until glossy, then press down evenly with rubber patch for final placement. Note: Bituthene is a heavy patch, so it might get skipped by ultra-light boaters.
Kayaks with a home repaired crack ARE NOT as strong as new. Please use good judgment when taking repaired boats to desolate or multi-day locations. These cracks can open back up with a couple of questionable lines or boofs. Welding a crack is useful to get you back on the water until your shiny new boat comes in ;0)