Kevlar repair - how to tell it's good?

-- Last Updated: Mar-13-09 7:23 PM EST --


I will very likely be looking at a repaired kevlar Valley Rapier 18 kayak with a crack to the hull that goes vertically for may be 6-10" on one side of the cockpit area. Bottom seems intact.

That same area on the deck has pretty big spider cracks on the gel coat.

The hull I think (can't see from the photos) is supposed to be repaired and gelled over fully and all cracked areas are supposed to have been patched from inside.

Just not all cosmetic gel coat spider cracks are fixed on the deck I am told. The rest of the boat seems new. The hull-deck seam does not seem to be broken from the inside though on the outside it is visible where the hit must have been. There were no holes patched in the hull, just a crack it appears.

The boat was supposedly new when a tree fell over it (I have no reason to doubt the story) and has been "professionally" repaired. Price is about 1/2 from new.

So, how can I tell it is well repaired, meaning strong enough? Cosmetics I can tell for myself if I care enough for them or not...

From a photo I saw of the internal patch I see white fibers in some areas where in others it does not have them visible. This seems to tell me that the patch used for glassing may not have been wetted fully. But it may just be the poor photo, I'll re-check on the spot. I probably should not be too worried if this is the only issue with the repair as this particular area is easily accessible.

Would about 50% be a reasonable mark-down (from a shop, not private party)?

Any other considerations? That might all be moot if I don't fit in it, but it looks like I might... And yes, unfortunately, it seems to have the old style rudder. I can't comment on the seat till I actually sit in it. So there is at least another $2-300 for a new rudder (may be) and possibly some more for a seat if the one in it does not fit me (Pat from ONNO might get some business from me finally if I go thru with this thing and need to swap these parts out).


Tought question. You might gain more
info if the layup, gelcoat, and repair are thin enough together that you can shine a very strong light through. This could be done with the room darkened. But gelcoat usually cuts light transmission a lot. What you would look for, if it could be seen, is the area of the repair around the break, and perhaps whether there is a concentric pattern of patches. Possibly there would be a color variation indicating whether the patching was done with glass or with Kevlar, but that’s probably immaterial. A good inside patch could be done with either material.

There’s a slight chance you could get a big caliper on the inside and outside of the patch, if it is near the cockpit. This would allow you to know how thick the patch is.

You can push on both sides… an optimal patch job should be somewhat flexible, not excessively stiff. You can tap on both sides and listen… it might make you look clever to observers.

Obviously sighting down the sides is important. You don’t want a slightly crooked hull.

Personally I wouldn’t worry about the spider cracks on the deck. I don’t think they will affect the life of the boat.

Maybe the seller has more info about how the patch was done. I think they really should be able to provide detail. Unfortunately, people have all sorts of ways of patching glass, and those who mainly patch Corvettes and powerboats may think their approach is just fine and not subject to review.

It sounds to me like you may be able to get a really good boat for a great price. Hope it works out.

Good advice
Here are a few more ideas:

  • Find out what materials were used to patch the boat. If epoxy or vinylester resin wasn’t used, I would be hesitant about it.

  • If the patch was done with mat instead of woven cloth, it wasn’t done properly. The patch should be the same material as the original construction, meaning Kevlar and possibly a fiberglass inner and/or outer liner layer.

  • The “white fibers” you mentioned are potentially worrisome. As you said it could indicate poor wet-out or air encapsulation. It could also mean that a patch was simply slapped over the damage area. A proper repair would entail removing all damaged material and replacing it.

    If you see any evidence of these things, factor in the cost of having the repair redone properly. If the boat is still a bargain, you may want to buy it anyway.

If you buy it and later decide that
the patched crack needs further reinforcement, let us know. It would be fairly easy for you to add a couple of Kevlar layers inside the boat.

If it’s an older Inuk you won’t fit; I had to remove my paddling shoes to get my size 12s in one. Pretty fast boat, but the semi ocean cockpit didn’t do much for me. The new version has more room, but not appreciably so.

WIll see in a few days…
Thanks on the feedback on the Inuk.

I’ll drive to see the Rapiers and may be a Marlin in a few days.

One other piece of information that emerged. Does this change anything, you think? The clear-coated Kevlar hull has been gel coat painted to cover the outside patches. Meaning the cracks have been patched from both inside and outside, including new kevlar seam on the inside. I suppose the thing is well patched and if anything probably stronger than new. But the weight is probably up to around #50 now, just about th elimit of what I want to carry about to the water and back…

Patching from both sides…
…can be a good thing, so that wouldn’t bother me at all. It may well indicate a well-done repair. However, gelcoat can also hide a multitude of sins, so I would advise going over the entire boat carefully. Frankly, I’s surprised that they would use gelcoat, as it’s much easier to use a quality hull paint and it’s considerably lighter.

Last check - photos
I posted online the photos from the Rapier 18 and 20 that I received from the seller.

Direct link:

The blue-decked is the 18, the grey decked is the 20.

Any final thoughts based on these photos? The password for the gallery is “rap” and I’ll be removing the photos in a day or two so if you happen to see them, please comment now.

Thanks again for the great advice - I appreciate it!

Not impressed by the inside patches,
and the patch inside the 18 isn’t wet out properly. It’s so easy to wet out glass properly. Puzzling. But what impressed me on the 18 is that the original cloth inside the boat doesn’t seem to show a crack. Maybe you could see one because you were there. It looks to me like the 18’s inside patch was just for stiffening a bruised area.

The picture of the 20 was harder for me to understand. There appears to be a big gap zone in the original inside seam, and then something, one or two layers of glass, was put there after the remains of a (presumably damaged) inside seam were cut or sanded out. The glass patch looks wide enough to stiffen a bruised area. Again, I can’t see a crack in the original cloth… maybe you could.

If the price is good and the boat is good, you could still get it. Anything deficient about their inside repairs is easily remedied… especially considering that the damage to the inside cloth in both boats does not look catastrophic.

Just guessing from appearance, but they may have been using a Kevlar/carbon blend. It would not make sense to use a cloth that is all Kevlar but with strands died black in one direction, because nobody’s going to see the inside of a kayak that’s in use.

I have not seen them yet

– Last Updated: Mar-16-09 6:21 PM EST –

Will check them out in a couple of days - just arming myself with information about what to look for since I have never worked with composite materials and only have theoretical knowledge of the construction/repair techniques...

I will be driving quite a few miles to see/test paddle them, so I would need to make a decision on the spot, unfortunately. Price is reasonable for the boat.

I would not call it a bargain basement price but it is not bad. With taxes and gas/toll it will still be reasonable if the damage turns out to have mostly cosmetic effects... Having already some blems will also put me at ease when I add my own -;)

Anyone else - last chance to comment
I’m trying the kayaks tomorrow - if you have any last minute thoughts about the repair, please share.