Fiberglass restoration


I’m wanting to restore an old fiberglass canoe. The keel is worn, but i thought the hull was in pretty good shape. When I started sanding off the old paint i started seeing what I think are stress fractures in the resin. Can anyone confirm what I think? What does that mean if true. Also with the keel I was hoping to get away with just filling the worn areas with non load bearing repair putty.


Sanding off the paint was not a good idea. If the canoe was painted, stripping it with a paint remover would do without any damage.

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Restoring and repairing are much different.
You can repair with some new epoxy resin and add some cloth for any weak spots. You can add resin alone on rough fiberglass and sand it. You can paint it.

Here is my restoration…

Sawyer Summersong - Google Photos

Restored Sawyer Summersong - Google Photos


It is really very difficult to make any definite sense out of your photo. First off, most composite canoes, fiberglass or otherwise, are not painted by the manufacturer, although there are exceptions. Most composite canoes have an external coating of gel coat, a polyester resin.

It may be that this boat was painted at some point. If so, my guess would be that the gray areas represent paint and the burgundy area represents the original gel coat which has worn through to white fabric in areas. If this is the case and the gel coat was cracked before painting, the cracks would “print through” the covering paint.

It looks like there are hairline fractures in the original fiberglass resin. Not the fibers. And it dosen’t feel weak or broken. I discovered this after i removed the paint or gelcoat.

Will stripper remove gel coat?

very nice

Unless the boat was constructed ridiculously resin-rich, whatever the resin is (likely polyester resin) would not have visible cracks unless you also saw broken fiberglass fibers. Polyester gel coat will very commonly develop hairline cracks but that is a surface coat that contains no fibers of any kind. No, paint strippers will not remove polyester gel coat.

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No, it’s OK to use stripper on gelcoat.

Based the picture, it looks like this may have had white gelcoat with maroon paint over it, or Maroon gelcoat with a layer of white gelcoat underneath, though I don’t know why a company would do the latter. The cracks appear to be in the resin, as you don’t seen any weave. That said, the hull is definitely weaker than it was originally.

I like the idea of adding a layer of fiberglass and epoxy, but it’s a lot of work and if you haven’t done it before, there’s a significant learning curve involved. At this point, your path of least resistance would be to sand it all back to the same level, prime it, sand as necessary, then paint it with a good hull paint like Interlux Brightsides. It will produce a nice, durable finish when applied with a roller and tipped with a brush.

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I have used Citristrip to remove paint from gel coated boats without any problem.