How To Fix A Cracked Kayak | Rapid Magazine | Rapid Media
Tools rest on a wooden table, to be used in repairing a broken kayak. Photo: Woody Callaway

Expert advice for welding your broken boat

Cracked kayaks are what nightmares are made of, but there is no reason that you cannot fix your trusted plastic boat and turn that nightmare into more pleasant memories. Boat repair guru Jamie Dors of Paddle Sports Repairs walks us through this straightforward but sometimes sticky fix so that this is not the excuse to get a new boat that you were looing for all along. Icy temperatures and craggy runs make spring paddling a recipe for cracked boats but this is possible all-year round from collisions with rocky shorelines, pins or other random events.


Know Your Plastic

Not all polyethylene is created equal. Most manufacturers use layered high-density polyethylene (HDPE). Alternatively, a few boats out there, including Jackson Kayak’s Elite lineup, are made of a variation called high-density crosslinked polyethylene (HDXLPE). Both types of poly are weldable, but HDXLPE is a lot trickier. “Its melting point is very close to its burning point,” Dors warns. This makes not scorching HDXLPE more difficult for most people without professional experience and highly specialized equipment. If you’re not sure what type of plastic you’re working with, contact the manufacturer.


In Your Toolbox

 You can weld plastic with either a heat gun or plastic welding iron. “The key is providing direct and constant heat,” Dors says. Hot air can pool material so it’s important to use a high quality heat gun with the proper focusing tip nozzle. A plastic welding iron may work better since it provides a more focused, consistent heat. If your boat’s manufacturer doesn’t sell poly welding sticks, they can be found at some auto or motorcycle body shops or online. For a professional look, try matching colors, or go with whatever you can get your hands on—chicks dig scars. If you’re working on a particularly large crack, you’ll want reinforcement that will help the repair to hold. Use mesh for cracks in flatter surfaces like the hull or decks, and rods to support cracks in awkward areas such as around cockpit combing. Stainless steel or aluminum work best becasue they won’t rust. Aluminum is lighter. Lastly, get your hands on a good scraper, some sand paper, a file and a surform for prepping and finishing.



Your boat has to be clean before you begin work. Hose it down and then sand or scrape the surface around the repair area. Opening up the crack a little with a scraper will help with the binding process. Finally, clean the area inside and out with mineral spirits as dirt and grease can interfere with welding.


The Fix

Whether you’re working on a deep gouge or a crack, the process of heating and mixing is more or less the same. Dors says holes are rare, “but if you’re this unlucky, you’ll have to find a scrap piece of poly, cut it to size and follow the same process as welding a crack.” Begin by preheating the material. If your hull didn’t crack on its first run down the river, then its surface is probably fuzzy and whitened. “You’ll know the surface is hot enough when it starts to get shiny and the fuzziness disappears,” Dors says. If you’re using a heat gun, you’ll also need to preheat the welding rod. When welding with a heat gun, lead with the gun and follow with the heated rod. Keep the gun one to two inches away from the work surface.

Mix the welding rod with the boat material using a stirring motion so as not to let the melted plastic pool. A steady, methodical hand will do the trick if you’re using a welding iron. Just take your time, ensuring the material mixes well, and leave the rest up to the iron.

If you’re using reinforcement, support the hull and realign the crack, then press the mesh or rod into the plastic as you heat. Allow the plastic to mix around the reinforcement for strength. “If it doesn’t mix well, the weld will pop open when it cools or is under stress,” Dors cautions.

Taking your time will ensure the heat penetrates the material completely. “Don’t rush,” coaches Dors, “plastic does not conduct heat well.”

Continue the weld at least a half-inch beyond the length of the damage. This will prevent cracks from continuing to form after welding. “The weld should be just as thick or thicker than the original surface of the boat,” says Dors. Reheating the area until its pliable and gently pressing it back into shape with a flat, metal object can smooth out lumps.



Continue to support the weld while it cools to restore the boat’s original shape. Let the plastic cool naturally. Adding water or anything else to cool it will weaken the weld. Once the weld cools, use a scraper, file or surform to smooth out the surface. Bruised egos will pass, scarring should be minimal and your boat will live to see another day on the river. Next up—perfecting your river-reading skills to avoid carnage in the first place.


This article originally appeared in Rapid, Spring 2011. Download our free iPad/iPhone/iPod Touch App or Android App or read it here.

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