Fiberglass on Wood - HELP

Bassn7

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I am replacing the rotted wood in a bass boat project. I put 4 coats of Spar Urethane on all the new pieces first. Now they are all in place and I want to fiberglass over them. Will the fiberglass stick good and solid to the wood coated in Spar Urethane?
 

kcassells

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Not sure if the glass will adhere. Best bet would have been to seal the would with poly or epoxy. Then the glass would have no problem adhering. How did you bond the 4 pcs together?
Lots of guys should chime in here. Good luck and Welcome aboard.
 

ondarvr

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Not good, it won't stick like it should, it's best to coat the wood with the same type of resin you are going to use for the entire project, never mix and match.
 

Bassn7

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I was worried about that. I wanted to be sure the wood was good and sealed with the spar first. I will try rough sanding to "score" the wood really well and attempt to lay just a base layer onto the wood. The wood should be really well protected...but I am concerned about the edges and butt ends keeping any rain out of the bottom of the boat.
 

ondarvr

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Spar varnish is a rather poor waterproofing product longterm, short term it sort of works, but....

There shouldn't be any exposed ends or edges when you're done glassing.
 
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Ned L

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Spar varnish is a rather poor waterproofing product longterm, short term it sort of works, but....

There shouldn't be any exposed ends or edges when you're done glassing.

Ditto,..... I won't say any more about that.

If you were starting with bare wood you could have used polyester resin, vinyl ester resin or epoxy. You can apply epoxy on top of polyester resin, but polyester resin will not adhere very well over epoxy.
 

jbcurt00

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If its a typical bass boat, its probably glass.....

If so, you likely need to just buy new plywood. If done properly, you'll deal w the edges and down side of the deck when you do them again.
 

tpenfield

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I am replacing the rotted wood in a bass boat project. I put 4 coats of Spar Urethane on all the new pieces first. Now they are all in place and I want to fiberglass over them. Will the fiberglass stick good and solid to the wood coated in Spar Urethane?

As the others have indicated, it was a bad idea to pre-coat the wood with polyurethane (sorry to say) . . particularly 4 coats of it. The fiberglass resin (polyester resin or any resin for that matter) will want to soak into the bare wood in order to obtain good adhesion strength. The pre-coating of the pieces is going to prevent that from happening.

A good approach would be to pre-coat the wood pieces with the resin just moments before applying the fiberglass layer(s). That way you will get better adhesion wood to fiberglass.
 

Bassn7

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I'm kicking myself for using the spar first. The boat is a 30 year old Cee Bee Avenger 182 Fish and Ski. It was completely rotted out and actually had 3 trees growing from the floor. The stringers were coated well and OK but I just circular sawed out all the floor I could see. As a fair weather fisherman I am hoping to get a good 10 years out of the 3/4 spar plywood. Boat, trailer, trolling motor and all working electronics and pumps only cost me $500 so I should be OK. I am going to rough sand all the edges and score the wood before the fiberglass and carpet. We will see. Thanks for all the help. I will use only fiberglass resin next time.
 

ondarvr

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I would recheck the transom and stringers, it's rare to have a floor that bad and have those two not needing a great deal of attention
 

kcassells

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Bass,
So shoot ovrer some pics on this thread. That will help everyone see what's going on.
 

Ned L

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What is fhe hull made of?? Fiberglass or aluminum?? If it is glass and will be completely encapsulated in glass structure I guess I would say go ahead. If it is aluminum and this is just bolted to the inside of the transom I might suggest not glassing it and just go with a couple of coats of a good oil bases enamel. The problem with what you now have is that any layer of glass can adhere no better than the polyurethane. If the glass starts to separate from the wood and gets water or moisture in there the only thing that can happen is for the wood to rot.
 
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