Fixing a Plastic (polyethylene) Kayak With a Hole in It




About: I am a year round outdoor educator traveling around the world taking youth into remote places to do cool stuff. I have been doing leather work since I was 8 at my parent's leather shop and love making thin...

I work for Pamlico Sea Base ( ) 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.

Step 1: 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.

Step 3: Attaching the Patch

This is truly the hardest part. I needed assistance because you have to move very quickly.
set up your work space so that everything is accessible.

1. put on your gloves
2. turn on the heat gun or ignite the torch
3. with the pliers, hold the patch at a corner
4. using the torch/gun, melt the patch to the point that it is droopy but be careful not to burn a hole in it. Its easy to burn a hole through it with a torch. A little harder with the gun. I use slow sweeping motions across the body of the patch
5. sweep the torch across the outer edges of the hole enough so that the plastic starts to turn a different color. This boat turned yellow when it was ready, others turn white. be careful not to stay in one place for too long or you'll have two holes instead of one!
6. you have to work EXTREMELY quickly, while both the patch and the boat are still hot. The patch needs to be pretty droopy and the boat sticky. you'll have to hold the patch in your hands and press it to the boat. Even with gloves on it gets a bit hot!

Step 4: Smoothing Things Out

Now that the patch is on, you need to make sure it'll stay on, hold water and look a bit better. This means you'll need to smooth things out. this part is really all about trial and error. It took me a good 15 minutes to get the technique down. Here's what to do.

1. get your torch and metal spoon or putty knife
2. frequently the edges of the patch won't be stuck to the boat even if the patch is staying stuck to the boat, I held the torch so that the flame went between the edge of the patch and the side of the boat until both turned yellow then I pressed them together using my gloved hand or the spoon.
3. to smooth things out: heat up a small area (4 square inches) at the edge of the patch until it turns a color but not to the point that it catches on fire
4. with small sweeping and frequent strokes, sweep the melted plastic of the patch out onto the sides of the boat. move quickly. as the plastic cools, or if you press too hard, the plastic with stick to the spoon. I would frequently wipe the hardened plastic off the back of the spoon using the cinder block
5. it is best to heat up a small section and focus on it until you are satisfied with the smoothness and then move on. don't heat up a long section and try to work because it cools too quickly
6. I turned the boat over and propped it up on a cinder block for better access to the bottom of the patch

Step 5: Almost Finished

Put the boat up on some saw horses if you have them and pour water into the cockpit. Watch for drops of water to come out of the patch. Work these areas over again with the torch.

Now if you want to, you can use the torch on the inside of the boat to transition the plastic of the boat to the patch. This time you're smoothing the plastic of the boat onto the patch. I think this step isn't very necessary unless your patch is leaking.

Now all you need to do is sand the patch smooth. Unfortunately my boss never got around to bringing me a sander so our boats are a little rough.

After you sand the patch smooth, reattach all your components and you're ready to paddle!



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    27 Discussions


    1 year ago

    Rather than smooth the edges with a spoon which tends to stick, I'd try to find a suitable tool made of silicone since it's non-stick and also fairly heat-resistant (usually up to about 550ºF - 600ºF). These days there are tons of silicone utensils found in cookware/kitchenware stores. Ideally I think something along the lines of a small stainless steel spatula that's encased in silicone at the flat end. They make some pretty small ones these days as specialty items for baking cookies and such... something like that should be relatively inexpensive for the relative ease and practicality it'd provide I think. Worth trying anyways! Silicone oven gloves might be a consideration as well for someone who does this kind of thing quite regularly!


    4 years ago on Introduction

    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

    ~ 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!


    7 years ago on Introduction

    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??

    1 reply

    Reply 4 years ago on Introduction

    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.


    4 years ago on Step 5

    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.



    5 years ago on Step 5

    you get much better results with a very sharp angled paint scraper than with sandpaper [which always leaves a fuzzy surface]


    7 years ago on Step 5

    This is a DIY project with the true spirit of DIY. Well done!


    7 years ago on Introduction

    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?

    1 reply

    Reply 7 years ago on Introduction

    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.


    Reply 7 years ago on Introduction

    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.


    Reply 7 years ago on Introduction

    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.

    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.


    8 years ago on Introduction

    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.


    8 years ago on Introduction

    I'd suggest using a heat gun to weld plastic instead of a torch, better fine adjustment of the temperature.