Delaminated Kevlar

-- Last Updated: Sep-07-09 4:34 PM EST --

Recently bought an old kevlar Wabash Valley X-Cell C-1 racing canoe. The original owner said he thought he bought it in the late 80's and the last two digits of the HIN are '87', so that sounds right. It's been stored (inside) for the last 15 years or so.

Unfortunately some of the kevlar seems to have delaminated(?). There are a few fairly large areas of the floor that are very spongy and crackly when pushed upon.

Is there anything that can be done about this short of throwing out the boat? I bought it cheap so I don't have much invested in it now and I've been thinking it would be fun to learn to work with composites this winter anyway. It would be nice to have a project that I didn't have to worry about destroying.

Would it be possible to just lay down new fiberglass/resin over the bad spots? Or would the bad spots need to be completely cut out?

Also, the entire boat has taken on a nice rich yellow/brown color, like the color of aged wood floors. I peeled off a few pieces of tape that had been placed on the hull and below these spots is what I'd consider the normal, yellow, color of most kevlar hulls. Don't know if that's indicative of a problem or not. I also got a Wenonah J-180 of the same vintage that was stored in the same shed for the same amount of time. No delamination that I've noticed yet and it still looks like the 'original' color.

Any ideas would be appreciated.



C1 kayak?
Sounds like a contradiction in terms.

It’s normal for “skin-coated” Kevlar boats to darken to a honey-brown color over time. Is the hull bottom foam cored? If so, the core may be shot.

Yeah, I meant canoe. Fixed the original post.

The boat has what I’d call a stiffening core in certain locations, like ribs and below the seat. Otherwise I don’t believe it does. I’ll have to look closer when I get home but I’m pretty sure there were problems even where there was no core.


Forgot I had a couple pics of the boat here on my laptop. After looking at then it seems the whole bottom of the hull is cored. That seems like it would complicate matters a bit more.


Is the “bad” kevlar on the inside or outside?

If on the outside, a new glass or carbon waterline may solve the problem.

On the inside, you can take a more precise approach, laying Kevlar patches down as needed with peel ply over the edges so they don’t need sanding.

We need to see those pics to offer advice that approaches useful.

Alan, Call me anytime on this stuff .
I can help diagnose and walk you through it.

Have the same problem with sailboats
I race small catamarans. Since no one can afford a new boat we all race very old boats (80’s vintage). the deck is made of a layer of FG then a layer of foan, then another layer of glass. After alot of use(15-20 years) the glass will get cracks and water begins to break down the foam and the hull gets soft and very week. If fact we had a 30 year old, very soft boat, break 2week ago in 15-20 mph winds. Snapped the hull right in 1/2 just ahead of the forward pylons.

I do not think there is much you can do to fix it. If you find out anything please post it here. My hobie 17 was make in 86 and is getting soft spots.

Took some pictures of the hull-

Took a closer look and think it may be that the core has rotted. Most of the kevlar looks good to my eye. Where it feels bad it feels bad on both the inside and outside. Near most of the bad spots there’s some damage to the hull, maybe that allowed water into the core?


Thanks Patrick, I just might do that sometime. Starting to read up on composites now so I’ll wait until I have a little firmer grasp so I can hopefully comprehend what you tell me. :slight_smile:


Doesn’t look hopeless in the pictures,
but of course they don’t show the squishiness. I have no experience with such extensive repairs, nor with foam core.

But if I were stuck on a desert island with your boat and a bunch of repair materials, maybe the first thing I would do is to cut a small window in the squishy area in front of the seat in order to get an idea of the nature of the core breakdown. I would also make a squishy map, marking areas that are soft, in order to get an idea of the extent of the repairs.

I would hope that, after a long in-the-barn period, the core has had a chance to dry out through the various breaks in the laminate.

If the squishy areas are not very extensive, it might be possible to lay E-glass (cheaper than S-glass) over the areas, inside and outside. The glass would be stiff enough to bridge the squishy area so that the soft core would make little difference.

I just can’t see cutting out large areas of the inside Kevlar and then trying to replace the damaged foam, followed by having to lay new cloth over the inside.

Well, that should be enough dumb ideas to stimulate discussion.

Ice, same same as Alan,
I am very familiar with exactly what you are talking about and have a cure. Call me anytime.

It’s done all the time on sailboat decks in particular (for topsides weight savings many sailboats are balsa cored).

Basically what they do is cut down just enough to get through the first laminate. They pull that off, scrape all the balsa out, put new balsa in, and put the fiberglass they had cut off the top right back in place, and fiberglass the seam. It’s a PITA.

But with a canoe, you’re talking some pretty tight and confined curves. I don’t know what the core is, but it seems like a real hassle if it’s dry. More trouble than attempting would be worth. My guess would be to try and see if you can flood some thinned epoxy into the core at the squishy spots (will add weight but stiffen/seal rotten core), and then add a layer of glass.

just make sure
the core is dried first. Above idea is used often on sailboat decks, drilling holes to dry the core, then pumping in epoxy resin.

The hardest part is sourcing the replacement foam. removing the inside glass layer in one peice is much easyier now with the vibrating cutter available today. Now even dremel and harbour freight sell them. I think it is a one day job. A weekend at the most. You’ll need the vibrating cutter/scraper, the RIGHT foam, epoxy, and fiberglass tape.

If I was getting the tool for this one job I’d get this one:

Sounds easy enough
I bet it’s one of those projects that sounds like it should be so easy and turns out to be a total mess. That’s how things tend to work out for me it seems, especially the first time I do it. This has two bulkheads/stiffeners that the seat mounts too that I’m sure will have to come out as well.

Anyway, I’ll probably give it a shot this winter sometime. That will give me some time to learn more, weigh my options and hopefully get some practice with working with composites. I’ll update the progress.



Yeah, epoxy sets slower in winter so
you have more time to get things where they belong, or to rip them out and try over.