Anyone have any experience welding polyethylene?

[mudskipper]

So far I haven't had any issues with cracking or damage, but it's only a matter of time for me, given the ages of some of my boats (I still have an Aquaterra Prism from the mid-90's!)

I bought a couple 200watt plastic welders (basically huge-size soldering irons) from polyvance recently https://www.polyvance.com/Kayak-and-Canoe-Welders-1/ , and I've been practicing on 5 gallon buckets. They market these kits for ATV and motorcross riders to repair broken broken plastic fenders, as well as kayaks.

A bucket isn't the perfect analog for practicing on, since they're thinner than a kayak hull, and not UV stabilized, but the general principal is the same.

Anyone have any success stories or tips to share?

[J.A. Veil]

I have repaired short cracks on two of my kayaks using a soldering gun and the scrap piece of plastic that came with my kayak (it was the circle cut out to allow a small storage bucket -- the manufacturer sent it along with the new kayak). A dedicated plastic welder could make this job easier. It is important that you use the same type of plastic in your weld as in the main hull. There are a bunch of videos online that show the technique. Here are some of the key steps that I followed using my low-tech method:

1) Drill a hole at both ends of the existing crack to keep it from lengthening.
2) Take your soldering iron and widen the crack slightly to allow more surface area for the new material to adhere to. I dragged the heated tip of the gun along the crack to do this.
3) Take a small piece of polyethylene (your dealer or the manufacturer may be able to supply you with a scrap of the same color or you can use some other polyethylene -- a chunk of a 5-gal bucket will work) and heat its edge with the soldering gun. When the edge gets gooey, rub/smear the material into the crack. Repeat this until the entire crack is filled.
4) When I complete step 3, the surface along the crack is uneven and elevated, and it looks messy. You can use a Dremel tool, sandpaper, or some other shaping tool to make the area look neater. This does not give you a better weld, but it does look neater (if that matters to you). My finishing skills are not good, but the cracks I repaired were in areas covered by other parts of the kayak, so appearance did not matter. In both cases, I added an extra support piece over the cracked and repaired area to spread the weight load over a wider area so cracking did not reoccur.

[mudskipper]

yeah, I’d like to find a junker kayak to practice on, something that has already been destroyed or massively hole’d, and practice welding that. I even put a Craigslist ad out for several weeks this summer specifically looking for broken kayaks, but never got a reply.

If anyone reading this has a trashed boat they’re waiting to cut up for the recycling bin, I’ll give you some cash for it instead, and haul it away.

PM me

[Memory Maker]

Those welders work really good. I got mine from Hobie. They have a hole in theirs so you can feed a plastic welding rod of the same color. You don’t have to file or Dremel after patching because the iron will allow you to smooth the weld so it is almost invisible. I have only used mine to fill holes after I took something off of the yak.

You may want to check with your dealer to see if they have any defective yaks the same color. You might be able to get an exact replacement piece if you cut out the piece in the exact location on the damaged yak. Also, the manufacturer may have some pieces they could send you.

[Oldbayrunner]

Another key to strengthening a crack is to use SS screen mesh. Melt the mesh over the crack and into the outlaying plastic. Then melt hdpe plastic over the area and smooth it it out as much as possible then sand it evenly. Afterwards take a heat gun to bring back the shine.

[clm]

I picked up my hobie outback from a rental place...over the years, people had repeatedly ran it aground with the fins down....There was a crack at the rear of the pedal well. I used the cheap soldering iron type....after drilling holes at each end like Mr. Veil stated...Got the crack hot, melted in some plastic that came with the kit, then covered it all with marine 4200 or 5200...This was all done on inside. Not a drop of water has came through in years.