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hull repair help

Mashmaster

Active Member
So my son and I tried our first fiberglass repair and failed. It is a learning process I know. If you look at the first two pictures you can see the hole in its original glory. Then we grinded the area and put four layers of chopped matt fiberglass over the hole. Covered it with release fabric and smoothed it out. After curing, we hand sanded it and you can see the area is perfectly smooth now but the crack reappeared. Should I regrind it out and try it again with the biaxial cloth which is thicker? Or fill the crack with expoxy fairing compound? That seems wrong. I don't understand why the crack appeared.
 

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Webfoot1

Active Member
You need to cut out all the damaged area till you have clean edges, then grind back/taper
12% of damaged area for a bonding area. Mat and cloth should be applied in alternate
layers. The mat keeps the cloth from cracking. You can cut out and start over with no problems
but if the hole is bigger you may need a backing patch such as cardboard to keep the
fiberglass from sagging into the hole. Keep the faith, there is lots of boat left to experment
on.
 

gzblack2

Member
OK, I think the alternating of materials is what I missed.
That is not the only issue. You need to cut out all the damaged material. The layers of fiberglass have separated, simply patching over this is not correcting the underlying problem. Adding cloth without removing the damage will make the repair last longer but eventually it will fail.
 

Webfoot1

Active Member
Well 12% minimum to give full bond strength which with
West Epoxy is listed as 5000 lbs. pull strength if I remember
correctly. Unlike polyester resin it has nih-removeablility.
 
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