Plastic Welding Clinic


Perhaps you were out paddling on a river, nailed a sharp rock and put a crack in your boat.  What now?  Bitumen tape or Gorilla tape is probably the fix to finish your run, but is there a better long-term solution?  Perhaps!


The topic of our last Winter Clinic was plastic welding.  We learned that it’s not really rocket science!  There are some guidelines to keep in mind when determining whether a repair is appropriate, and some tricks that might make your repair a longer-term solution.


The first consideration is the plastic from which your boat was constructed.  Crosslink plastic, as used on many Jackson kayaks and older boats cannot be welded.  To be appropriate for welding, your boat needs to be constructed from linear plastic, as are most modern roto-molded polyethylene kayaks.


The second consideration is the extent and location of the crack.  Welding cracks in areas of substantial wear or stress will probably not be a viable long-term solution.  A weld might make the boat functional for friends to use on those easier runs or for use in the pool, but not for that class 4 or 5 waterfall run.  The ideal crack to weld is a small crack in a low-stress, low-wear area.  We can all dream, right?


What do you need to weld a linear plastic boat?  Not much!  Solutions for welding guns can be a hot air tool like the $250.00 Weldy Plus that we use at Alder Creek, or as simple as a Wagner Hot Air gun for $29.99.  What advantage do you get with a gun like the Weldy?  The ability to carefully control the heat vs. the high/low setting on an inexpensive gun.  Whichever solution you choose, an attachment like a wide slot or condenser nozzle will give you more control and precision.

You can purchase generic rods of HDPE, (high density polyethylene), but a better solution is to see if your kayak’s manufacturer can provide rods or to cut your own from a boat from the same manufacturer.  Often times enough material can be cut from the inside of the cockpit coaming to get a rod or two.  This also provides the advantage of a good color match.


Other tools to consider are a good scraper to clean up and bevel both edges of the crack, and scrape some of the excess plastic after welding, and a roller, or type of tool to put pressure on the fresh weld as it cools.  Some people also choose to drill a hole at either end of the crack prior to welding.  The logic behind this is that it may keep the crack from continuing to travel.


As far as the actual process of the weld, a picture, or in this case, a video is worth a thousand words.  Liquid Logic has an outstanding video on the actual process, which can be seen at

Boat Welding

Hopefully this is one of those skills you never find a need to use!  If you do crack a boat and don’t want to try repairing it yourself, bring it down to Alder Creek and we can help you determine the suitability of welding and even repair it for you.