Author Topic:   Fiberglass Repair Ritchie JuniorMember posted June 21, 2002 11:00 AM             I notice on another page some talk about repairing fiberglass. I managed to aquire some knowledge on this over the winter. My CL16 had been patched repeatedly in its days as a scout training boat, and I decided to fix every old patch on it. The boats are made from a polyester resin. When you patch old fiberglass, the bond between old and new is an adhesive or secondary bond. Polyester Resin does not adhere to polyester as well as epoxy does, so in repairing polyester fiberglass, epoxy is your best bet. Once you have epoxy resin layed onto fiberglass mesh, you can build it up with a second layer and create a chemical or primary bond between the layers by laying the second one on while the first one is still tacky. You have to remember that the thicker you lay resin, the faster it dries because the chemical reaction creates heat. If you put it on thick enough, you can actually create enough heat to burn you hands. The patches I layed in my boat were as large as 10" by 6", and seem to be as strong as the rest of the boat. I used the West System Epoxy which is very expensive, ($50 per quart) but very easy to use. You can buy a set of dispensers for the Resin and Hardner ($12) which make for very easy mixing, and also additives for the epoxy to make adhessive and fairing compounds ($8-$15). Your best bet for sanding is to use a belt sander with 60 grit paper to shape your patches, and then an orbital sander stepping your paper from 40 to 80 to 120 grits. For painting I used Inturlux's Brightside Primer and Paint, and am very happy with the results.

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