Fiberglassed some of my stringers yesterday...

[unhip_crayon]

This morning I found air pockets around the edges...What do I do now and how do i prevent this from happening again?

Should I sand it down and fiberglass over it or inject it with resin

 

[erikgreen]

Re: Fiberglassed some of my stringers yesterday...

If you want good strength, you'll need to sand it down and re-do it. Sorry.

Post some pics... most likely you're missing a fillet or have one too small. Fiberglass can't turn corners very easily, thicker cloth is stiffer than thinner, although mat is a bit better. Where it turns a corner sharply it has a tendency to form bubbles, sometimes even after it's been pressed into place for curing.

Stringers are one area you definitely don't want bubbles, except maybe a couple on top or somewhere non critical.

The strength of the fiberglass laminate comes from an even pairing of glass (or other) fibers and resin, and depends on a uniform mix of the two to transfer force and weight around easily. A bubble forms a spot where there's no support, and it makes for cracks and delamination, or worse provides a spot for water to collect.

Even filling bubbles with resin just makes them look good, they're not really strong because they still don't have the right mix of glass and resin, and they don't have a uniform structure.

Erik

 

[unhip_crayon]

Re: Fiberglassed some of my stringers yesterday...

I'm only getting bubbling near the top, Bottom is ok. But I'm worried that when I screw in my floor, well A, it won't be even or B, fiberglass will crack.

 

[unhip_crayon]

Re: Fiberglassed some of my stringers yesterday...

http://img13.imageshack.us/i/img0339e.jpg/

http://img13.imageshack.us/i/img0337n.jpg/

^^This is the worst section...no idea what went wrong. The thing is....They dont feel like air pockets

http://img197.imageshack.us/i/img0338g.jpg/

 

[Robert D]

Re: Fiberglassed some of my stringers yesterday...

I'd just sand the bad area's and re-glass. No big deal, but it buys a lot of piece of mind.

 

[erikgreen]

Re: Fiberglassed some of my stringers yesterday...

Yeah, those are bubbles due to the glass not wanting to turn that sharp corner. Up to you if you want to re-do them, typically you glass the top only to protect the wood unless you're using foam core stringers.

For peace of mind, I tend to do things the best I can, even if it means re-doing a significant amount of work. For me it's a personal thing, but if you're ok with some bubbles there it won't affect the strength of the stringers very much if at all.

Erik

 

[chrishayes]

Re: Fiberglassed some of my stringers yesterday...

To eliminate that from happening in the future, you should use a router with a round over bit. Saved me a ton of frustration when I did mine! its like a reverse fillit...other than that, looks like a good glass job.

 

[chrishayes]

Re: Fiberglassed some of my stringers yesterday...

Actually, I just went back and looked at your second picture and I must say that I would grind that out and redo it. I just looked at the first pic which looked like good glass work with just a few bubbles at the very top...Your call, but I would redo. sometimes it sucks but you have to just keep at it until the bubbles go away even if that means hanging out with it while it sets up...usually as it gets tacky you can ge tthe bubleeees to lay down.

 

[NoKlu]

Re: Fiberglassed some of my stringers yesterday...

I agree, the glass work in the second pic needs to be redone.

 

[Yacht Dr.]

Re: Fiberglassed some of my stringers yesterday...

Hello Unhip..

Sorry to say... you came across whats called a "learning curve" ..

A few quick pointers..

1. resin coat your stringers b4 you layup. It will help the air from coming out of the wood.

2. Get ALL your glass cut and ready to layup b4 you kick any resin. Putting on just one or two layers of mat..then stop.. will set you back many hours of prep. Do all your lams at one time if at all possible. ( work in sections if you have to ) .

3. As already stated above..round your edges.

IMO your going to have to grind basically everything off in those pictures ( way too much air .. you dont want to layup over that much air m8 ) .. Sorry..

YD.

 

[unhip_crayon]

Re: Fiberglassed some of my stringers yesterday...

Alright...I've finally sanded out all the pockets and torn out most of the bad fiberglass work for a fresh start.

Heres my Idea....stapling the fiberglass to the stringers on one side, stretch it to the other side and stapling it again. This should hopefully completely prevent any bubbling. (on top of rounding the edges)

Once its dried, Ill either rip out the staples, or leave em in there and fiberglass a small patch over em. Im worried they may rust over time so Ill probably rip em out if I can.

Thanks for the help!

 

[erikgreen]

Re: Fiberglassed some of my stringers yesterday...

Hello Unhip..

Sorry to say... you came across whats called a "learning curve" ..

A few quick pointers..

1. resin coat your stringers b4 you layup. It will help the air from coming out of the wood.

Right idea, wrong reason Wood doesn't outgas that much, especially in the short time between application of resin and curing. What it DOES do is suck up resin.. like a sponge. Unless the surface is sealed it'll pull resin right out of layup, either creating bubbles where air leaks in to fill the void or giving you a resin poor weak layup. Use a foam roller compatible with your resin to coat the wood first.

What I personally do is wet the wood first with the roller, then lay dry glass in place (it'll stick to the resin, but still permit easy re-positioning) then wet it out using short pours of resin near the top of the glass and the roller again to push it down into place. Use the roller to spread the resin, wait a couple minutes for the glass to soak it up, then hit any dry spots with the roller and possibly a bit more resin.

2. Get ALL your glass cut and ready to layup b4 you kick any resin. Putting on just one or two layers of mat..then stop.. will set you back many hours of prep. Do all your lams at one time if at all possible. ( work in sections if you have to ) .

Good advice, especially when working with poly resin... work wet on wet.

3. As already stated above..round your edges.

As an alternative, you can lay a flat strip of cloth on top of the stringer, then just lay up the vertical sides, and don't turn that corner with a single piece of cloth.

Erik

 

[jonesg]

Re: Fiberglassed some of my stringers yesterday...

to me the only joint that counts is the vertical to horiz.
I glassed my stringers before installing, pre-sealed the edges,
then just seamed them to the hull.
Like this,