You call that a scratch?
You ain't seen the bottom of MY boat.

These things happen with astonishing regularity. In my case, I get a bunch of scratches at every landing as the shoreline by me is rock.

Unless the scratches go through the layer of resin (epoxy, or if your boat is old enough, polyester) and hit the wood, or rip the glass cloth away from the wood you should not get any water penetrating. If water does get in, it will probably only be a few drops. At worst it will cause some minor delamination of the glass cloth. You won't sink, and the water won't show up on the inside of the boat. A dab of duct tape over such a spot keeps the water out for quite some time.

Unless you have major tears in the glass cloth, and a lot of water getting in contact with the wood, hold off on fixing anything. At the end of the paddling season you can make your repairs.

At that time: Deep tears, or any areas where the cloth has delaminated need to be patched. Use coarse sandpaper and a power sander to remove the resin and glass cloth, going down to the wood. Use a light touch. The coarse sandpaper gets through the glass cloth on its own. Sand back to where the glass has a good band and then "feather" the edge, so there is a 2 to 4 long, tapering transition from the top of the wood to the top of the surrounding glass cloth covering. This gives the patch lots of bonding area, and makes the patch's edges invisible.

Regardless of the resin used in the construction of your boat you will want to use epoxy resin for repairs. It sticks to both polyester and epoxy, so it is the remedy of choice. A small amount goes a long way.

Paint over the area you sanded with some freshly mixed epoxy, lay on a piece of glass cloth a bit larger than the area you sanded, then go over that with a light coat of the epoxy. Get the edges of the cloth wet with resin, and be certain to forc out any airbubble that might be trapped under the weave of the fabric. A piece of stiff plastic used as a squeegee might help. Once the resin hardens (the next day, probably) you put on another coatover the patch. Let this harden two days. Then, using a sanding block and hand power, sand down the rough edges of the patch. Stay away from the center. Just get the outer edges smooth, and blend them into the rest of the boat. Wipe off all the sanding dust with a damp cloth, let the area dry competely, and paint over it with another coat of epoxy.

This should be enough epoxy to completely saturate the glass cloth, but you may still see the pattern of the weave of the cloth if you look closely at the surface over the patch. is a result of the resin sitting on top of the cloth and following the curves of those glass fibers. After this coat of epoxy hardens, gently hand sand over the area to smooth it with 100 to 150 grit sandpaper.

At this time you can also hand sand the other areas that have scratches that have simply gone through the finish, but have not gone through the glass cloth. if you have a very deep scratch you don't have to sand all the way to the bottom of it. The varnish will fill it a bit, and it will be disguised pretty well. the lightly hand sand the rest of the boat, just roughing up the finish a bit, and creating some "tooth" so the next coat of varnish will bond well.

When all is sanded, wipe off all the sanding dust with a damp cloth and put on a coat of a good marine varnish that has a UV inhibitor. You can buy this from a boat shop, or online. When it drys you hand sand again, with finer grit sand paper (150 to 225 grit) and then put on a second coat.

As you can see, the time involved is spread over several days. That is the reason you put this off until the end of hte season. While epoxy resin and varnishes dry on the surface in a rather short time, they continue to harden over a period of several weeks. When you take your boat out next spring the repairs will be extremely tough.

Hope this helps.

Nice looking boat. You say it came from an antique shop. Hmm, it looks younger than me.

PGJ