fiberglass repair?

D

David Allen

Active member
I am helping my son repair a fiberglass canoe. The are several deep cracks that we have sanded down and are now ready to fiberglass.


After speaking with a friend that knows more than I do I found out the I was doing may repair incorrectly in the past. Specifically I would apply a small piece then a large piece until the area was built up to where I wanted it. I found out from them that I should have been using applying that largest piece first then the smaller one.


Okay now I am second guessing what else I thought I knew. Historically I would have used the heaviest cloth on the based layer then light cloth. Is that correct?
 
Grind out all loose material. If it's a long single crack, drill a stop hole at each end. I patch both sides. Start with the smaller patch. Clean grind and sand. Go larger next.
Go pics on you tube...
 
David, here's a video from West System that suggests largest patch on the surface and working out with smaller package.



I've never done a repair with multiple layers at once as they suggest, but I have laid up as many as four layers by laying them on top of each other and epoxying each as I go.
https://www.youtube.com/watch?v=6N7YMr6E564

In truth, I'm not sure it matters much whether the largest patch is next to the original glass or on the outside, but I've never gone wrong following instructions from West System.
 
I've patched a few whitewater kayaks using the smallest piece on the outside method and they've always held up well. Charlie Walbridge in his "Boatbuilder's Manual" (1982) offers the scientific explanation " The smallest piece goes on the outside; don't ask me why; it just seems to work." ;-)

Here is a link to a page with a very good step-by-step on canoe patching. They claim the large to small lay-up "maximizes the area of the secondary bond" http://blog.fibreglast.com/fiberglass/repairing-fiberglass-canoes-with-the-double-patch/

Unfortunately I can't comment on laying up the different thicknesses of glass as I only did patches of multiple layers of the same weight cloth
 
You must log in or register to reply here.
Back
Top