Hello All,
It looks like I have developed a crack on the keel of my Kevlar canoe. I attached a picture below, it is approximately 4" long.
I have read about people doing " gel coat repairs" or just using epoxy.
Looking for advice on best way to repair this, is it just gel coat or something more.
Thanks!
It looks like more than just gel coat damage to me. Sometimes it is hard to tell since the polyester gel coat is sometimes more elastic than the underlying structural fabric so the gel coat might hide more extensive damage beneath it.
If this is an actual crack in the structural fabric of the hull I would expect to see some evidence of injury on the inside of the hull opposite this. Many canoes are laid up with an interior layer or layers of aramid, such as Kevlar, with multiple exterior layers of fiberglass. It might help to tell us what make and model this canoe is and what year it was built.
In a canoe with interior layers of Kevlar the aramid fibers will often not fracture because they fibers are stronger than their bond to the resin matrix. So they don’t break, they just pull out of the resin. When this occurs it shows up as one or more white lines in the Kevlar representing fibers that have disassociated from the resin.
If you can post some photos of the interior of the hull opposite this injury.
It is a Mad River Explorer 16 Kevlar. The Serial number is MAD11098B000.
Below are three photos on the interior opposite the injury. I don’t see any obvious damage on the interior but I also don’t know what I am looking for.
Thanks!!
I had a similar cut on my skin coat boat. Didnt think much of it until I saw water weeping out one day.
To me, that looks like a cut into the core caused by something sharp (log, sign post, etc). If you can push on one side of the crack and the other does not deform in kind, then you have cut the fabric and exposed the core. Its not the end of the world, but does need to be patched at minimum with some epoxy and ideally with a strip of fabric.
No I don’t see anything on the inside that would suggest a through and through crack. But it looks to me as if your canoe might possibly be the Explorer/Lightweight version which had a bottom core of Core-Cell foam. The foam core could well hide any damage that extended through the outer structural layers.
Like MClmes I am still suspicious that there is a cut into the structural fabric. Unfortunately, you may not be able to confirm this without removing some of the overlying and adjacent gel coat. You would need to do so to apply an external patch of fiberglass. I think at this point your options are to do that or else just gutter out the existing crack a bit, fill the void with epoxy, and paint over with some type of paint that is a reasonable color match.
If it were my canoe and you saw obvious broken fibers I would apply an external patch.
Thank you for the quick replies guys!
I could definitely see it being caused by something sharp. I was in low water and it may have been a sharp rock. I can’t really get either side of the crack to deform, but maybe that is because of the core-cell foam that @anon64780766 mentioned.
It sound like to me the following steps are needed.
Do you guys know of a one stop shop to get the materials to do a repair like this?
Lastly, If I have a paddle planned would a duct tape “patch” be sufficient for the short term while I wait for materials?
Appreciate all the help!
I have “repaired” through and through cracks that were leaking in composite canoes with Gorilla Tape and the result was so good I had to sort of force myself to do a proper repair.
With the damage where it is right in the center of the V bottom you have geometry working for you as any external force will approximate the crack, if any, rather than cause it to distract.
If you do find disrupted fibers I would apply an external patch of 6 ounce per square yard S fiberglass. S fiberglass is significantly more expensive the the common E fiberglass but also considerably stronger and more abrasion resistant. And you won’t need more than a yard of it. Cut any patch with its fibers on the bias so that the fibers of the weave and the warp cross over the ridge of the V bottom at a 45 degree angle rather than perpendicularly. That will double the number of fibers crossing the linear crack.
Personally I wouldn’t mess with reapplying gel coat but you can if you want. You will never get anything close to a color match with it. I just paint over the repaired area with any paint that is a reasonably close color match. Of course, the paint will get scratched off and scratched up over time. At which point you just get out the can and spray on some more.
I really like sweet composites for repair fabrics. The type of S fiberglass that I have used and recommend is the style 6533 which is $23 for a 36 x 60 inch piece which will be much more than enough.
https://www.sweetcomposites.com/Fiberglass.html
I also favor West Systems epoxy and would use the 105 resin with the 206 slow hardener. Sweet also sells epoxy but you really won’t need that much and might not want to shell out a total of $60 for a quart of resin with the appropriate volume of hardener (although epoxy is very handy stuff to have around). Sweet also sells “repair packs” that contain 19 grams of 105 resin with the appropriate pre-packaged volume of hardener. The hardener is the somewhat faster 205 version so pot life is shorter, but you won’t be mixing up much epoxy at a time for a patch of limited size so that is not an issue. Six such repair packs should do the trick and will set you back $26.
In the world of cycling, we have an N+1 approach. N equals the number of bikes currently owned. N+1 equals the number of bikes required (road bike, gravel bike, cyclocross bike, bike with fenders, fat tire bike, mountain bike, bike with panniers, track bike, beach bike, fixxie, hybrid bike…you get the idea.)
Now is a perfect time for you to purchase a new (to you) kayak, which will give you some flexibility in fixing your current kayak. Good luck with this…you will probably end up with six…I hope you have the room to store all of them. 
I would clear out the gouge slightly with some careful grinding. A Dremel tool would be good. Fill the void with marine epoxy mixed with microballons, silica filler.
I like fiberglass tape for an application like this, especially on the keel, maybe 3 inches wide. Then paint it. Back in the water.
I got in the materials for the repair. Really appreciate all the detail @anon64780766 !!
I started to sand the area and the good news is that it looks like the cut did not penetrate any of the fabric layers. (see pic below)
At this point should I just put on some epoxy and then paint? or does it still make sense to put on a layer of the fiberglass?
Also is there specific type of paint that is best?
@lml999 Trust me I would love more boats and will definitely add some at some point!
Thanks again for all the help all!
I think you are good. I would fill the weave of the exposed cloth with epoxy, let it cure, sand flush, and paint.
