Question:
I imagine this question has been asked a million times, but here goes. I
have a 1989 SeaRay 190 fiberglass boat. While tearing out the floor and
stringers for replacement, I made a critical mistake. I put a hole in the
hull using my rotozip tool. I made a 4" trough from the inside of the hull
where I was cutting and went throught the hull in one spot. Where I went
through the hull, there is a 1/4" diameter hole. The remaining area is
obviously very thin from where the material was removed.
I've seen several sites say different things about how to patch the hole.
Some say simply cover the outside with duct tape and put in thickened epoxy
resin in the affected area. Others say that you should put 3 layers of
fiberglass on both sides, sand, etc. This type of boat has no balsa core,
it's simply 3/8" fiberglass.
My question is what do I need to do for a 20' fiberglass boat? It will be
used in both the ocean and freshwater. Is the thickened epoxy strong enough
to hold it without coming loose later?
What do I use to thicken the resin? What do I put on the exterior of the
boat after the repair? It has anti-fouling bottom paint in the area
already. Do I need to sand that prior to putting the resin in (from the
interior)?
Answer:
- I would repair it from the inside and leave the outside
alone. Make sure your gouge is clean and rough, you might
have to widen it a little with an angle grinder to make a V.
Then fill with about three layers of epoxy/glass cloth
(knitted would be good). The glass should be wide enough
to spread the load. A shallow V will give you a lot more
contact for bonding. Put a little duct tape over the hole
to stop the goo from running everywhere and you shouldn't
need to do anything from the outside.
Wear a mask and goggles when grinding fibreglass.
- Thickened epoxy alone won't give you any strength, but it
will allow you to graduate the bottom of the trough so that
the glass cloth will lay nicely without any tricky corners.
Colloidal silica is probably best for strength. You may not
need a thickener if the glass will lay nicely.
