Repairing 14" gash in UL Kevlar advice

-- Last Updated: Apr-20-15 1:15 PM EST --


Or if that doesnt work:

TL;DR version: (TLDR=Too Long; Didn't Read)
My boat is messed up in a bad way. Look at the pics. Im going to attempt the repair.
1. What weight of Kevlar cloth should I use for the inside
2. What weight of Fiberglass cloth should I use on the outside?
3. How should I support the shape of the hull during the application of the first layer?
4. Is 2 internal Kevlar and 1-2 external Glass layers enough?
5. Give me any advice you think I should know

Long version:
Yesterday I was canoeing along when I struck a submerged post. I didn’t get a good look as it was completely below the water but I think at 1 time it was a fence post or something similar with a concrete base and a metal post. Much to my bad fortune, it was pointed straight at me at a 30* angle and I ran right into it. Hard.

The pics tell it all, but it initially struck a rib just above the diamond core. It slid along for a couple inches before it pierced the skin, tore a 14” long gash, then impacted the next rib and finally stopped. It was bad. Really bad. Like, I’m crying a little for my boat bad. In the words of the wife, “ it looks like the Titanic”. That’s not good.

Anyways, I’ve done about 8 composite repairs so far and I’m going to try to repair this myself. I’m going to use West 105 and 205 fast hardener so I can do 2-3 layers per day (2-3 day total project time).
Im wondering what cloth layup you’d use and how does this sound for a repair plan
1. Clean area with acetone
2. Trim away torn and raised fabric
3. Tape off area to be worked on
4. Sand area with 60 grit inside and out
5. Clean again with acetone
6. Cut large piece of Kevlar that extends past damage 4” each direction for base layer (what weight of cloth?)
7. Cut smaller piece of Kevlar for 2nd layer that extends past damage 2"
8. Cut large piece of fiberglass for outside of hull base layer (again, what weight of cloth?)
9. (possibly cut smaller piece of fiberglass for 2nd outside layer)

Now, here is where I need advice. Because the damage is very near the chine, how to I make sure the existing hull stays the shape it should be?

The ribs and core are obviously very stiff, but the single layer cloth in between them is not rigid at all and the damage is near the chine. How do I keep the flimsy damaged cloth it in place while glassing the first layer on the inside? I was thinking of taking smooth plastic film and taping it in place on the outside of the hull and using that for support. It should conform to the existing hull semi well and should be substantial enough to take a little brush pressure.

11. Support outside of hull with clear plastic film
12. Glass 1st layer of Kevlar on inside (wait until it cures)
13. Acetone, sand, Acetone
14. Glass 2nd layer of Kevlar on inside (wait until it cures)
15. Acetone, sand, Acetone
16. Glass 1st layer of glass outside
17. Acetone, sand, Acetone
18. If needed, glass 2nd layer on outside
19. Pull tape
20. Acetone off the blush and blend edges with 180, 320, 400, 600, 1000, 1500, polish

Thanks for any advice!

Link doesn’t work forme
Please repost drop the “s” . Just “http” should work.

Ill try again

– Last Updated: Apr-20-15 12:05 PM EST –


– Last Updated: Apr-20-15 12:10 PM EST –

As for what weight of aramid fabric to use I would suggest 5 oz/sq yd. This weight wets out fairly well and fairly quickly.

Personally, unless you are working in quite cool temperatures, I would use West 206 hardener. You can apply a second layer of cloth while the epoxy of the first layer is still "green". In fact, you should do so whenever possible to achieve the best possible "chemical" bond. I appreciate the longer pot life and working life of the 206 hardener and find that at ambient temperatures near or above room temperature it cures plenty quickly enough to apply at least 2 layers in a day. If you have experience in composite repairs you will probably be fine with the 205 since you will not be wetting out huge pieces of cloth.

For the outside I would definitely use a plain weave S fiberglass. S 'glass, though more expensive, is significantly harder and stronger than E 'glass. If you plan to use one layer I would probably go with 6 oz/sq yd. If using two layers I would go with 4 oz/sq yd. A single layer of 4 or 6 ounce per square yard fiberglass when wetted out and the weave completely filled with resin should be nearly invisible. It will stand slightly proud of the surrounding hull but it should not be too objectionable cosmetically.

You did not mention peel ply. I would use peel ply (or mold release fabric) over both the aramid and fiberglass patches. This will allow you to get the smoothest possible edge without sanding. Aramid doesn't sand well anyway and you would like to avoid excessive sanding on the exterior.

I have used both clear plastic packing tape or thin transparent plastic of the type used for overhead projector slides to maintain the contour of a cracked hull. I would try the tape first since it is very difficult to secure plastic film in such a way that epoxy can not leak out underneath the film. The cured resin should separate from the tape pretty easily. If any tape remains behind it should be pretty easy to sand it off.

I think your general scheme for repair with at least 2 interior aramid patches and at least one external fiberglass patch is sound. I would only add that when using multiple layers maximum strength will be gained by having the fibers of the various layers aligned at different angles. For example, if the first patch is cut along the weft and warp the second should be cut on the bias. I would probably go with two concentric 5 oz/sq yd interior aramid patches and one external S 'glass patch initially. Fill the weave of the external patch with at least one additional epoxy application for maximum smoothness and to remove the matte texture left by the peel ply.

After everything has cured completely assess the result. If you feel you need more strength and/or rigidity, either apply a third internal aramid patch or a second external fiberglass patch.

If you have to apply a second or third patch over epoxy that has cured beyond green, remember to wash off the amine blush from the prior layer's epoxy.

I like your planning, but suggest
you consider taking it to someone like kaz of

He makes light, thin hulled boats, and is experienced at repairing same. His boats are all S-glass outside, Kevlar inside, and the sides are often thin and flexible.

In a perfect world…

– Last Updated: Apr-21-15 2:30 PM EST –

Ya, If I had the money I'd like to have it professionally repaired, but due to finances I dont think I can convince the wife to free up $400+. I dont know what Kaz would charge, but I've had repairs quoted twice in the past and they were well more than I could spend.
That was in MN, but everything seems more expensive out east so Im not hopeful that the repair would be affordable. That said, Im fairly happy with my previous work, and although it probably took much more sanding than a professional, everything has come out smooth and strong so Im optimistic that I can patch her back together and make it look pretty.

I am with you all the way
I have repaired many ultralight Kevlar canoes and carbon/Kevlar kayaks, but never to the extent that your boat needs.

If however, that was mine, I would be attempting the repair myself.

It looks like one heck of a challenge

I can’t help you, but I can wish you good luck

Jack L

Yu are on the right track and have good comments by pblanc.

The repair will not be as bad as you think. My first canoe was an old Sawyer Cruiser that had been wrapped, ripping out both sides at the turn of the bilge. I paid $25 for that boats and repaired it with glass cloth and epoxy. I paddled it for many years and finally sold it for $400 in about 1995. Just proceed in an orderly fashion one step at a time. The repair will be stronger than the rest of the boat.

Info from Johnny’s boat shop

– Last Updated: Apr-23-15 10:28 AM EST –

If you check my string kevlight repair.
I was advised too call Johnny's you may want too also.
But things I remember he said you are doing different:
Sand all the way to the Kevlar but don't fuzz too much.
He said it will not last unless you do.
Also he say to not fan the edges. Sand sharp edges down to mat.
And to make it last it needs a coat of uv protection he suggested spar varnish. Covering with spar varnish also eliminates a lot of polishing and sanding.

If it is the same as my morning star he said it has a uv protective coating nothing will stick too.
Hardest hull too repair. :(
But it must be sanded off or nothing will stick.
I had a run get on the stuff of the 105 + 207 it peeled right off.

West systems advised me to use 105 + 207.

I am a novice just passing tips from Johnny's hope it helps.

Btw I told Johnny that is was said on here that I should call him and he had probably repaired more hulls than all of us combined. He said: "I don't go for that Internet stuff much"
Joe :-)

Never had a patch peel from Kevlar
though I do sand close to the fibers.

Off the finish, not kevlar, I think.
That’s what I think that he meant.

Good point

– Last Updated: Apr-23-15 2:52 PM EST –

I refinished my boat last year with a fresh coat of epoxy and then a coat of Bristol Finish lacquer for UV protection.

I should probably try to sand below the Bristol Finish before doing the outside patch. Good point.

Also, a plug for Bristol Finish catalyzed lacquer; This stuff is tough as nails! I highly recommend it in place of spar varnish for most applications with a couple caveats:
1) its extremely stinky. Extremely. I painted with lacquers for 4 years and Bristol Finish is one of the nastiest I've ever used. You know its good because it burns your eyes and killed a bee that flew in my garage overnight. Dont even think about using this stuff unless you have a carbon respirator, and ideally a full face one if you have sensitive eyes. Also, make sure they wife is gone because she will complain about the smell.
2) it dries extremely quickly as most lacquers do. You have a wet edge for maybe 10-20 seconds. You will need to spray it, work in tandem, or only do half the boat at a time. They offer a 'tropical reducer' additive thet slows the drying time, but West Marine didnt have it in stock when I needed to do my repair so I cant comment on how much more working time it buys you.

I got the kevlar and glass ordered, so I think Ill dive into this project next weekend.

Pictures of my semi-final repair
I patched the hole 5 weeks ago, but due to moving for the 2nd time in 5 months I just now got around to sanding and paddling it.

It turned out as well as I could hope, maybe better. The inside (3 layers of 5oz kevlar) looks ugly but is structurally stringer then original. The outside is 2 layers of 6oz s glass. I sanded off most of the 2nd layer of glass smoothing and shaping the patch. Overall I maintained the original shape well, so im happy. The white parts are west systems epoxy with thickener as I had to fill in a damaged rib.

I still want to do a skim coat of epoxy to fill in a couple air bubbles I exposed during sanding and add a coat of 2 of spar varnish to the outside for a little uv protection.

A question I have is why didnt my glass fully wet out? I dont seem to have a problem with kevlar or carbon, but I have had 2 glass patches not fully wet out. its 80-90% wet out, but you can still see some fibers.

Paddling pics