The problem you’re having is common and easily remedied. The fiberglass wasn’t the only material used on the outside of your canoe. There was also a layer of marine varnish. This further seals the surface and provides a glossy appearance. Trouble is, this varnish also gets dull and worn over time because of abrasion and the effects of UV rays. You can re-establish that new canoe finish with two or three coats of marine spar varnish meant especially for use on boats. Before you apply it, however, give the canoe a light sanding with a quarter sheet finishing sander fitted with 120-grit sandpaper. This creates a slightly roughened surface that holds the new finish properly. Sanding also removes any loose flakes of varnish that may be peeling off. Marine spar varnish comes in satin and high-gloss formulations, depending on how shiny you want your canoe to be. The main thing is that it be rated to resist UV exposure.
How can I restore the lustre of a cedar strip canoe that’s covered in fiberglass? The surface is dull and scratched.