Delaminated cedar strip.

[HaroldH]

Hi,
I am new here and know very little about CS canoes. I bought a used one quite a few years ago and used it a few times before I noticed that some areas of the hull had developed some big weak spots. I hung it in my shed and have left it there until now. I have just figured out what the prob is: for one large area on 1 side of the hull the fiberglass reinforced epoxy or polyester has come unattached from the cedar strips. I grabbed a loose end and tore big strips off. Of course I have lots of questions (1) is there any particular type or grade of fiberglass that I should use to patch the hull? I only kind I have used is quite heavy duty stuff used for auto repair (1) The new fiberglass will, of course, come in a flat sheet whereas the hull is curved in both directions. How do I avoid creating wrinkles in attaching a flat surface to a curved one? I will leave the other questions until later.TIA for any helpful comments.

 

[Todd Bradshaw]

Delamination is pretty common with fiberglass sheathing using polyester resin. Since there is not, and never has been, a polyester resin formulated for use on wood, these days anybody who knows what they are doing will use epoxy resin instead, which is generally delam-proof. Fiberglass does not come in sheets; it is a woven cloth which is then placed on the hull and saturated in place with resin. Then the weave pattern is filled using multiple thin coats of plain epoxy, then sanded smooth and finally varnished to protect the epoxy from UV damage. Most canoes use six ounce fiberglass woven cloth.
In your case, the delaminated areas could be feathered out and patched with new cloth and epoxy. It's not a perfect solution and won't prevent future delamination in other spots, but it would get you out on the water. I suppose you could try removing all of the outside glass using a heat gun and re-glassing the outside using epoxy resin and new cloth, but the vast majority of old strippers aren't worth all that work and expense. It makes more sense to start over and build a new boat.

 

[John Sand]

Todd is an expert. I can add a couple of suggestions from my experience repairing peeling fiberglass. I tape the cloth in place before wetting out, the tape should be on the dry part overlapping the original. Don't try to completely fill the weave the first time, too much resin with cause the fabric to lift. I trim the edges with a sharp scraper when the first coat is "green", dry to the touch but not yet rigid. You can probably find videos online. Good luck, happy paddling.

 

[Worth Gretter]

Harold, I'm going to offer a different opinion. Usually the hardest part is getting the old fiberglass off (heat gun and many hours). From what you said, it seems it came off easily. My suggestion is this: try to get the rest of the glass off, then sand the wood and see if you can get it reasonably smooth. If it does not take too much effort for these two things, then you can consider a new coat of fiberglass (with epoxy this time).

 

[HaroldH]

Thx guys. I guess 'sheet' was a poor choice of words. What I am trying to say is that a fiberglass 'mat' or whatever that comes in a roll would naturally lay on a flat surface. Is there any special technique needed to get it to sit flat on a curved surface w/o creating wrinkles?

 

[Worth Gretter]

I think the biggest problem is the stems. When people put stem guards on their composite (fiberglass, Kevlar, carbon, etc) canoes, they typically use bias tape which has the fibers diagonally (instead of side-to-side and up-and-down like normal fabric). But I think that is only necessary for the most severe curves. You should be able to get the fabric to lay flat elsewhere.

 

[Todd Bradshaw]

You have some terminology problems going on here. Fiberglass mat is made by sticking a whole lot of short (2" or so) chopped strands together with some styrene-soluble goo and forming it into "fabric" of sorts. That is not suitable for strip canoe construction. Fiberglass woven cloth (which is what you want) is more like burlap cosmetically, but it is made from full length glass fibers. It will drape nicely over curves as long as they aren't too sharp. As mentioned above, the stems can be a problem, so they are usually wrapped with bias-cut strips of cloth, which will conform to the sharp angles and curves present on stems.

Before we end up writing an entire book to explain all this stuff here, you would benefit drastically by picking up a book on cedar strip canoe construction and there are plenty of them out there. It will teach you just about everything you need to know on the subject of building these boats and how to repair them. Ted Moore's book "Canoecraft" for example would be a valuable resource to read.

 

[MGC]

Cut to the chase, this canoe is one that is probably past the point of no return.
Todd very kindly and subtly suggests that the alternative to totally stripping it is to consider building one from scratch.
With consideration to the effort that is necessary to attempt to repair this hull and the likely less than ideal result, that seems to be solid advice.
Mike

 

[HaroldH]

Thx for the advice. I have ordered the Canoecraft book. I will hold off any more questions until I have read it. My initial questions here were to see if it was practical for me to repair. Applying fiberglass cloth with epoxy seems to be fairly straightforward. There are no severe curves to deal with. The delam areas peeled off quite easily. It looks like I just need to taper('fair') the edges with sandpaper to create a smooth transition. i.e no need for a heat gun. The delam areas are all on one side of the boat