Instructables

Fixing a plastic (polyethylene) kayak with a hole in it

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I work for Pamlico Sea Base ( http://pamlicoseabase.org ) as a sea kayaking guide. One of our trailers is built for canoes and doesn't have fenders over the tires. Unfortunately someone wasn't paying attention when loading it with kayaks and the sides of a few boats sat on the tire for a 2 hour trip. We now have 3 boats with gaping holes in them.

It isn't very likely that you'll have a kayak with such a large hole, but whatever the size, here's how to fix it.
 
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Step 1: Materials and Tools

Picture of Materials and Tools

You'll need:
1. some sort of patch. we had an old trashed boat we could cut up. The only other plastic I know that will stick well are those big blue 50 gallon drum/barrels. Make sure you wash it out well!

2. gloves

3. heat gun (I used a blow torch which isn't great but works)

4. a water bottle (for safety reasons)

5. a large metal spoon or putty knife

6. a pair of pliers

Step 2: Prepping the kayak and the patch


Sand the edges of the patch and the edges of the hole. I used a grinder for the patch to make things go faster. (I had 3 boats with holes in them) Some people will tell you to sand the side of the patch that will stick to the boat and the plastic of the boat around the hole the patch with attach to. I don't know if this helps the patch stick or not because I didn't bother doing it. It's probably worth trying.

If the hole is next to the seat or any rigging or anything that would either get in the way or catch fire, remove it. For the boat pictured, we had to take the seat out, take the paddle holder off, and move the rudder cable.
LynxSys2 months ago

That's a solid fix. The metal-spoon-and-propane-torch method is tried
and true amongst whitewater and expedition kayakers who have big holes,
very little equipment, and less time (and who really don't care about
the cosmetics of the repair). You're clearly resourceful and got the job
done well and quickly with what you had available.

If anyone
reading this is considering repairing a plastic (polyethylene only!)
kayak and does care about cosmetics (or has the budget for some
equipment), I'll echo some of what's already been said in the comments: a
plastic welder is really the way to go. I used to be the repair guy at a
kayak shop, so here are some tips:

~ Get a temperature-controlled
plastic welder (I use the Model 7 Airless Welder from Urethane Supply
Co. and like it a lot) and practice with it.

~ Cut your patch to
the size of the hole, shape it with a heat gun, and bevel the edges of
the patch and the hole so that the patch doesn't fall in while you're
working.

~ Get some extra plastic of the right color, preferably
welding rods (if you call the manufacturer, they'll usually at least
send you some scraps of plastic for free).

~ When doing the
repair, make sure that the edges of both the patch and the hole get hot
enough that they actually melt and you can mix them together.

~
You can smooth down your repair with the tip of welder, similar to how
the hot spoon is used in this Instructable. Don't use a sander. You will
make your patch thin, and it will look rough.

I hope this comment is helpful to someone!

dmcghie2 years ago
so question, if your not in a time crunch situation wouldnt it be easier to fix it with a fiber glass patch would need a few people to do it but i think it would actually make the area tough enough (i assume the patched area wasnt as strong as the rest of the boat) to withstand troubles on the water??
LynxSys dmcghie2 months ago

You don't actually want to use fiberglass (or anything else adhesive) for a permanent fix, because pretty much nothing will stick to polyethylene. Repairing polyethylene by melting it together creates a repair that is actually just as strong as the rest of the boat, provided that you melt it all the way through, that you get the weld to mix well, and that your patch is the same thickness as the rest of the hull. This is true of polyethylene because it is a linear plastic (i.e. not crosslinked). If you have a kayak that is thermoformed out of a plastic like ABS (which is crosslinked), then it requires a totally different repair procedure, and melting it together won't work.

Could you have put the rough oversized patch you cut INSIDE the hull, against the damaged hole, then scribe the hole outline onto the rough patch, then trim it to the scribe line?

You could then use the trim strips as improvised welding sticks to join the patch to the hull.

I've never done this, just wondering if you think that might work.

Courageous and useful instructable. I love it.

windshadow4 months ago

Awesome tutorial .

I bent out some crushed motorcycle bags similarly with a heat gun. They had thermoplastic structure with leather over top. As soon as I heated the interior "gently" they could be bent back out to original fatness.

I have some coolers that have been drug around. Abrading off the corners and exposing the urethane insulation . I was thinking about beefing up the corners with plastic .

Now that I have seen your tutorial it looks like a doable project.

Thanks.

kjlpdx1 year ago
you get much better results with a very sharp angled paint scraper than with sandpaper [which always leaves a fuzzy surface]
crickle3213 years ago
This is a DIY project with the true spirit of DIY. Well done!
dfrelow3 years ago
how did you get that enormous hole?
dunnman3 years ago
I am curious as to whether to cut the patch to the exact size of the hole or would it be better to cut the patch oversize and sort of stick it over the hole and then smooth out the edges inside and out?
WayfinderAli (author)  dunnman3 years ago
If you have the heat gun and plastic welding sticks (plastic filler rods), you can cut the patch to the exact size and shape and then use the plastic welder and plastic welding sticks to seal the seam. If you don't have that equipment (which I didn't) the only way to ensure that the patch will stay in place, keep water out, and withstand use and abuse, is to cut it larger than the hole and then smooth out the edges.
If you get the plastic filler rods, you'll have to have someone hold the patch in place or duct tape it in place and work slowly.
dasgemuse3 years ago
the proper way is to use a heat gun and plastic "filler rods" it will look 10x better
WayfinderAli (author)  dasgemuse3 years ago
I've used the filler rods on other boats and they worked really well for holes but I don't think it would work very well with such a gaping hole. If I had been able to cut a plastic patch that was exactly the same size and shape as the hole, the filler rods would have worked well. Also this instructable was made with the few resources I had on hand. I had two days to get 3 boats fixed and back out on the water.
i of course meant to use a patch along with filler rods. lol
WayfinderAli (author)  dasgemuse3 years ago
You're right, it would look way better with filler rods. But wouldn't the patch have to be just about perfect in shape? I hope this doesn't happen again, but it could happen again this summer, and it might be worth getting the rods.
i would just buy a new one :)
WayfinderAli (author)  R2D2Laboratory3 years ago
Unfortunately they're pretty pricey. around $1,400 retail and the Boy Scouts (who own and operate Pamlico Sea Base) don't have enough money to go buy new stuff when old stuff gets damaged.
kevinlee3 years ago
I use a heat lamp and pretty much the same process (we use powdered resin) to repair fuel cells on tanks at work. Gallon milk jugs will also melt and blend for fixing cracks. Just grind out the crack and melt it in.
CaseyCase4 years ago
I'd suggest using a heat gun to weld plastic instead of a torch, better fine adjustment of the temperature.
You can also use a smaller torch. I bought a small MAPP gas welder kit for fixing plastic, it is easier to control due to its size. Its also cheaper then a full size torch and bottle set up. I'd think even a plumbing torch set up would do the trick.
WayfinderAli (author)  mackamitsu3 years ago
That torch was a pain to use. It was what camp already had sitting around so it was what I used. In hindsight, a heat gun is probably the way to go. Although I think its hard to get a big patch to melt enough with a heat gun to make it stick, so in that case I think your smaller torch idea would be the way to go.
WayfinderAli (author)  CaseyCase3 years ago
After fixing another boat recently, you are totally right. A heat gun is WAY better. Although I don't know if I could have gotten the patch melted enough to make it stick with a heat gun. It is really easy to burn a hole through a boat with a torch.
AntMan2324 years ago
If it was me, i'd duck tape over it but, if you really want to patch it...
crapflinger4 years ago
i used to work at an outdoor outfitters, and we sold kayaks. some of the kayak manufacturers (blackwater, dagger, etc..) have a policy in place to keep shipping down for blem boat returns (blemished), instead of shipping the boat back, you just have to cut out the serial number plate and ship it back, then they ship you a boat. this tends to leave you with a gaping hole in the boat.

the guy that owned this shop wasn't exactly the most ethical guy, so he'd typically cut the numbers out of at least one boat out of every shipment, then we would have to patch the boats as cheaply as possible and then they would sell the boats at a discount (if you sell a $1,000 dollar boat for $500, and you technically never paid for that boat, well then that's 100% profit). we would use pieces cut from 55 gallon plastic drums.
lemonie4 years ago

Did you lose rubber from the trailer-tyres?

L
WayfinderAli (author)  lemonie4 years ago
The boats that didn't have such complete holes, that is that had some plastic left at the hole site, had some black/rubber streaks on them. One of the boats we have has rubber marks but wasn't on the tire enough to cause a hole. The trailer tires did leave some rubber on the boats but we didn't notice any big change in the tires. You would think the rubber of the tire would break down faster than the plastic and we would have had blown tires but we didn't. I think the same tires are still on that trailer a year later.