polyethylene repair

My Necky Manitou 13 (made of superlinear polyethylene) has picked up a nasty gouge somewhere along the line, and I’d like to repair it if possible. I’m not talking about a hole or crack, and I’m not talking about a minor scratch or scrape - it’s somewhere in between. I know that poly boats are not known for being easily repairable, but does anyone know of a reliable, durable product that I could use to fill the gouge (hopefully the repair would not be noticeable afterwards)?

Wow, great timing on the question
wwleslie, as I was thinking about posting a Polyethylene repair thread.

I researched on resealing bulkheads in poly boats last year and learned that POLYURETHANE caulk was recommended as it bonds well with polyethylene.

This year, nephew came up with the idea to use POLYURETHANE caulk to repair scratches to the hull.

  1. clean the area(s) thoroughly

  2. use a safety razor blade to trim excess material from the area(s)

  3. lightly sand the area(s) to roughen them up a little and increase the surface area of the bond

  4. use a piece of cardboard or scrap of wood for a pallet and deposit the polyurethane caulk in a pile

  5. using the safety razor deposit caulk into the scratches and gouges, packing the caulk in and smoothing it as you go

  6. let the caulk cure for two or more hours (depending on weather)

  7. if needed trim the repairs with a light sanding or with a razor

    The caulk I found was a neutral dark tan color.

    Nephew repaired his boat early in the spring and the repairs are holding up fine. I just did my boat recently.

    Nephew’s boat is “Cloud” color and mine is “Lava”, the repairs are noticeable but not overly intrusive on either color. Besides, that part of your boat is under water and the fish don’t care!

polyurethane caulk
Sounds like what I need. Where do you get the caulk - at a hardware store or do kayak shops sell it? I did an online search and a bunch of roofing supply places popped up. Thanks for your help.

polyurethane caulk 2
Check that. I found a 3M product - 5200 Adhesive Sealant (it’s polyurethane and intended for underwater marine use) sold by Jamestown Distributors - about $10 for a 3 oz. tube. Do you think that would do the trick?

I’ve used 5200 for installing bulkheads, and it was very sticky and very strong. I recall that it was black, though, and anything it touched it stuck to, so be careful about spilling it.

I can’t imagine it would sand well at all - though the razor blade would likely work.

5200 won’t work long term. I’ve done a number of tests and it will not adhere well long term even though it is amazing stuff. Get the boat to someone with a polyethylene welding gun and it will be fixed correctly and the repair will endure.

Home improvement store
for the Polyurethane caulk. They should all carry it.

Or as Salty said get the professional fix with a poly welding gun if you’ve the time and money to make that happen.

The polyurethane caulk will cure kind of soft so it is a stop gap measure at best, but should extend the life of the hull.

Old Town did sell a polyethylene repair kit for DIY use. Possibly they (or another company) still do. You could check a local paddle shop about ordering something like that. In my area it is very rare to see one on the shelf.

DIY polyethylene repair apparently involves heating the material correctly to “polarize” that section of the hull to allow the melted in filler polyethylene to bond correctly. There are cautionary tales out there about melting holes in a hull, however!!!

If I were getting this done, I would have a “pro” do it.

The two shops I frequent in my area have both told me not to bother with polyethylene welding unless the hull has an actual hole in it.

Hence the polyurethane caulk method.

Hope this helps,


I have a Tempest 170 Poly and until recently it had unusually dry compartments. Recently, I started noticing a little water ghetting into the day compartment and it turns out my hadches are still sound but the bulkhead has come un bonded at the very bottom and is letting some of the water that gets into the cockpit seep into the day compartment.

What I’m getting at is would the POLYURETHANE caulk be the thing to use to reseal the bulkhead or should I use the 3M 5200 or is there still a better option?


Rotomolded? Foam Bulkheads?
That is what I used the polyurethane caulk on. Sealed some leaky bulkheads early last year ('07) and they are still holding well.

The bottom of the bulkhead and halfway up the sides can easily be done with a caulking gun while the 'yak is right side up on saw horses. The top half is trickier to caulk gun. Use a pallet with a pile of caulk on it and paint it on with a popsicle stick.

Strapping the 'yak down too tight/close to the bulkheads is probably what caused mine to start leaking. (Due to the flex of the poly deck.) I’m very mindful of that now every time I load the 'yak on the rack.