Fiberglass resins, i'm confused.

[sti1471]

I hear that gelcoat does not stick to epoxy resins. Then I hear that Polyester resins and gelcoat are not waterproof.

So if I am repairing a below the waterline fiberglass hole, how should I go about this?

I the repair is "boarderline" waterline, and it is only in the water about 1 time a week for a few hours.

Do I use fiberglass cloth with polyester resin and gelcoat on top, or do I use epoxy, fiberglass cloth and no gelcoat? I want it to be repaired with as little notice as possible.

 

[Robj]

Re: Fiberglass resins, i'm confused.

If polyester resin was not waterproof, then all tne moored boats would slowly sink. Just do your repair with poly and it will be fine. More important than the resin is the prep work make sure you prepare the surface properly. I have worked with both poly and epoxy and poly is much easier to work with.

 

[sti1471]

Re: Fiberglass resins, i'm confused.

Thank you for the reply.

Should I be adding a gelcoat the top of the poly or if I do not sand it is there no need for a gel coat?

 

[oops!]

Re: Fiberglass resins, i'm confused.

yep ....add gellcoat after the repair.

sand the repair smooth...(or somewhat smooth) then paint or spray on the gellcoat....this layer should fill the imperfections of the surface of the fiberglass.....let get sticky......then add more gellcoat.........sand smooth with 320 grit....then all the way up to 1000 grit.....then polish.

if you get the color match of the gellcoat right......you wont sven see the repair area.

hi rob.....comin back up?....boat will be on the water soon

 

[sti1471]

Re: Fiberglass resins, i'm confused.

great, thanks for the information. From the tings I have read, it looked as though I was being instructed to add the gelcoat first then glass and resin the inside. I am going to glass and resin the inside, and outside, then add gelcoat to the finished glass.

It seems as though a lot of posts i have read on "thehulltruth" were saying poly resin was not waterproof and should not be used on repairs below the waterline.

 

[Cadwelder]

Re: Fiberglass resins, i'm confused.

great, thanks for the information. From the tings I have read, it looked as though I was being instructed to add the gelcoat first then glass and resin the inside. I am going to glass and resin the inside, and outside, then add gelcoat to the finished glass.

It seems as though a lot of posts i have read on "thehulltruth" were saying poly resin was not waterproof and should not be used on repairs below the waterline.

Most all boats on the water are made with polyester resins. Vinylester is a bit better choice for below the waterline, but the poly will hold up well also. The gelcoat that oops told you about it is what adds the extra waterproofness.

 

[oops!]

Re: Fiberglass resins, i'm confused.

as far as polyester resins not being water proof....

we are taliking on a microscopic level........virtually every glass boat manufactured from 1950 till the mid 90'5 is made from poly resin.

they have floated for 60 years....poly resin is just fine.

the confusion comes in when stregnth is concerned.....people say poly isnt strong compaired to epoxy. well they are correct....epoxy is stronger then poly.....
BUT....poly is 10 times stronger than WHAT THE AVERAGE BOAT BUILDER NEEDS.......using epoxy is like putting a steel patch on a wood house, instead of using wood in the first place.
wood also is not water proof.....however...there are a ton of wooden boats.......i might be wrong....but the guy that discovered north america was on a wooden boat. no epoxy !

 

[ingalp01]

Re: Fiberglass resins, i'm confused.

wood also is not water proof.....however...there are a ton of wooden boats.......i might be wrong....but the guy that discovered north america was on a wooden boat. no epoxy !

Haha, and I doubt that they had an anti-fouling bottom paint on the Nina, Pinta and Santa Maria... LOL...

 

[Yacht Dr.]

Re: Fiberglass resins, i'm confused.

Haha, and I doubt that they had an anti-fouling bottom paint on the Nina, Pinta and Santa Maria... LOL...

No.. Im sure they didnt have fouling paint .. but their stock of cotton im sure was in supply. And their TAR ..

Thank you for your history lesson though. Any other opinions would be helpful ...

YD.

 

[sti1471]

Re: Fiberglass resins, i'm confused.

I bought some west system lol resin for 191 dollars for 1 qt. I just saw "bondo" fiberglass resin for 11 dollars a qt. Is there a difference? Saving 50% off can really add up on resin when doing wood sealing and boat repairs..

 

[oops!]

Re: Fiberglass resins, i'm confused.

yes....take the epoxy back.

once you go down the path of epoxy...you cant turn back and your choices are totally limited afterwords.

a standard polyester resin kit is what you need....i would avoid the bondo repair kits at wallmart or other big box stores.

this is a waxed resin.....nothing wrong with it....but then you have to take the wax off after it cures...this is a bit of grinding.

in the signature below this post....there is a link.....click it......use the index and look for a standard fiberglass repair or standard gellcoat repair.....a little reading on that thread will do you wonders bud.

cheers
oops

 

[rrumba]

Re: Fiberglass resins, i'm confused.

ok, so there is a TON of reading and even MORE information in that thread alone. it is very informative and took me awhile to get through it and by the time i finished reading it all i feel like i forgot the information i needed because there was more info than empty slots in my brain so it kept filling up and dumping out the older info and then the thoughts of other things to add come into play as you continue to read.....they just don't work the same as when they were younger, brains that is.

 

[oops!]

Re: Fiberglass resins, i'm confused.

the hull extension thread is the most informative thread on glassing there is on this forum imho.......with pros commenting and explaining the glassing process...how it works...and compairisons between different types of resin.....its great......glad it made sticky....there is too valuable information to let it go into the archives. pay particular attention to posts from a guy called ondarvr.

 

[sti1471]

Re: Fiberglass resins, i'm confused.

Ok,

So I gutted to old wood from my transom and cleaned it out. Cut my new transom wood sheets and they are currently drying with a layer of oily resin on them. My question is, when it comes time to patch the holes in the outside skin of the transom where my engine mounts broke through, do I fiberglass the inside with cloth before I put the new wood in and then glass the outside after the wood is in, or just the outside? I've seen some patch from the inside and some patch from the outside, I guess it just depends what your repairing. In my case, a 3x3" hole in the transom.

Thanks guys