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Fibreglass-over-plywood kayak moisture damage

Phil C

New Member
Jun 5, 2020
Looking for some advice on how to handle mold/rot that has developed in the wood under the fibreglass.

I am refurbishing a pygmy coho by adding hatches, bulkheads, deck rigging, then refinishing. It was built 18 years ago but it was stored outside for a while. It has a clear finish so that you can see the beautiful mahogany wood grain and color. But there must have been some pinholes in the finish as there are several places that have ugly black blemishes from moisture/mold/rot. I tried a test repair in one spot by sanding off the fibreglass right down to the wood and installed a fibreglass patch (see picture below). That spot is is now clean,sealed, and strong, but because the rest of the wood color had faded with age, this repair patch is noticeably darker in color than the rest of the wood, so it didn't turn out looking as nice as I had hoped.

So my question is do I need to worry about removing the rest of this mold? Ie, is it only cosmetic or do I need to get rid of it to prevent more damage? My options are:

a. Reseal with a coat of epoxy, maybe add some paint/accents to improve the appearance, then varnish it and start paddling.
b. Continue with my patchwork repair, and end up with a clean, but blotchy looking boat.
c. Bite the bullet, and take the entire deck down to the wood, then re-fibreglass and refinish and much greater cost and effort.

I am leaning towards option a. because it doesn't seem to be spreading and when I repaired it, it was just on the surface of the wood. If you are far enough away and squint your eyes, the finish looks great! Thanks,

pigmy coho repair 3.jpg

pygmy coho repair2.jpg
I'd go with option a) also....or even less.
Has the epoxy 'broken down'? Sometimes epoxy will go yellow and crack and flake if UV-damaged.
If the epoxy is OK, I'd just give a scuff sand with 220 grit and lay on some varnish and go.
If you can find some 'darker' varnish that might help to even out the colour.
I don't know if ColorFX dyes are compatible with varnish - You could contact WoodEssence (in SK) for advice on that.
I believe it was stored out of the sun. Now that I look closer at it, the epoxy seems in good shape overall, so skipping the filler coat of epoxy is a good thought, thanks!