Repairing Fiberglass cracks with just resin?

[bowman316]

I have a hatch on my sailboat that has a crack in the fiberglass where the hinges attach to the door. I repaired the one with some fiberglass cloth and polyester resin. Not that side is more secure that the other side. The other side has some smaller cracks in it.
If I just ran some resin over those cracks, would that sure it up? It is hard to get glass on everything, since there are several small 90 degree angles involved. one of the 90 degree angles has a small crack running down the seam. I figured filling that crack with resin might sure it up. After sanding it down of course. And I wiped it down with mineral spirits before glassing.

What about polyester vs epoxy resin? this is a 1970 grampaign sailboat. I heard that is prob polyester?

 

[ondarvr]

Re: Repairing Fiberglass cracks with just resin?

Polyester resin has little strength on its own, so just filling the cracks with resin won't do much. Epoxy is a little better, but if it cracked the first time due to stress even with glass in it, then neither one alone will be the right solution.

Cracks need to be routed out, sanded and then reglassed for the repair to hold up long term.

In other words, either do it right, or don't waste your time.

 

[Woodonglass]

Re: Repairing Fiberglass cracks with just resin?

Pics really help us to help you. IMHO ondarvr is correct about the repair. Prolly not what you wanted to hear.

 

[oops!]

Re: Repairing Fiberglass cracks with just resin?

to back up what the above two posts said.

do remember when you glassed the other hatch?

in the bottom of the bucket u used to mix the resin.....there was a little left right?....

after the repair was fully cured,,,,,did you take the cured resin out of the bucket?

it crumbles in your hand with very little effort....

kinda like wax paper crumbling....but it broke up like peanut brittle in to a thousand little shards.

THAT is what you are suggesting to put on your boat.

resin needs glass to be strong. without it.....it is useless

 

[bowman316]

Re: Repairing Fiberglass cracks with just resin?

I used small patches of fiberglass sheets near the bad cracks. One side of the hatch had cracked all the way thru. The other side was more secure, but was not tight.

I patched the bad crack, where the port hinge attaches, and that was quickly more secure than the other side.

So I put some patches in on the other side. It is very firm now, but I still might put on another layer of glass, just to back it up. Right now I only have 1 layer of glass holding the big crack together. (I had to lean a brick against it while it was drying, so it would stay flush with the rest of the hatch.) It kept wanting to spepperate.

 

[bowman316]

Re: Repairing Fiberglass cracks with just resin?

now, can i just spray paint this hatch with some spray paint (enamel) from home depot? I know Gel coat is prob what's reccomended. but will spray paint be good for something this small?

You will be walking on this surface, so will it be slippery with normal spray paint on it? I might wax it after i paint it.

 

[oops!]

Re: Repairing Fiberglass cracks with just resin?

buddy your not done yet.

that hatch is cracked there due to the hinge point being stressed.

to just glass over where the hinge attaches will work for a bit.....but not for long (a season or two)

i would glass the back side as well.....grind off the gellcoat.....so you are bonding glass to glass....and run 2 layers of 1.5 on the back lip and into the roof of the hatch....if you can...one layer of 1708 at the same time in the same place....and your good.

then after cure....just a quick sand to get every thing semi smooth....then prime and paint. (chances are ....that if you just paint....the paint will alligate on the glass)

alligate= get all wrinkley

 

[bowman316]

Re: Repairing Fiberglass cracks with just resin?

yea, i put glass on both sides of the crack. I just used the cloth that home depot sells. 3M no. 20128

the crack is on the 90 degree edge, and both sides now have a few layers of new glass holding it together.

 

[Home Cookin']

Re: Repairing Fiberglass cracks with just resin?

you can also mix powdered fibers with the resin to make a putty; easier to work with than mat for small or odd-shaped applications.

if the repairs are just cosmetic and non-stress point resin alone will fill small cracks or nicks.