You people would know this. Repairing fiberglass, if an outside part is visibly compromised, is there a lot of internal damage that you should cut around?
Posted by checkoutmuhhat@reddit | sailing | View on Reddit | 11 comments
Like is it's a 1-inch horizontal break, what's a reasonable amount to cut out around that and work on replacing it? I'm talking about hull damage and it's on an outrigger canoe, but fiberglass is fiberglass. Since I'm bringing it up, I watch the crap out of Sailing Uma, they are masters with fiberglass and hull work.
So then I just have a simple question, is there a significant worry about an internal spread of damage when it comes to fiberglass, or does it stay kinda contained? Does it rot?
CatsAreGuns@reddit
It does not rot, damage can be worse below the surface. If you want to repair grind/sand till you see/feel/hear no more damage. (Tap a solid part, tap the compromised part, hear the difference) Then grind/sand some more to create room for the scarf joint. Surface prep and precut glass fiber (patches in increasing size) Glue the smallest patch first, each patch should be 2cm/an inch bigger than the last so it adheres to the last patch and the hull. Let it dry and fill + sand and then fill+sand till its smooth.
checkoutmuhhat@reddit (OP)
Do you start from kind of a thin patch in the center and let that harden, and use that as a mold of sorts? I've never worked with fiberglass and I have an opportunity to, so I already appreciate what you said, knocking the hull exhibits where the problems are. I've done drywall before and I'm guessing it's pretty similar. Have a good hefty starting point and build on top of that.
BenderRodriquez@reddit
You don't need to let it harden in between. Usually you let it harden if you need to build a very thick patch since the hardening releases heat. Very thick laminates can cause a thermal runaway if done all at once. If you let it harden you either need to cover it with peel ply or clean and sand before next layer because hardening causes amine blush on the surface.
checkoutmuhhat@reddit (OP)
I had no idea about the heat, and knowing bit the finishing effect of that, thanks, great information. You have a recommendation for a beginner purchase? A kit maybe?
mofukkinbreadcrumbz@reddit
West Systems 105 and 205 resin and hardener. They also have plastic cups and stir sticks that the epoxy doesn’t stick to. You’ll also want cheap brushes (I prefer foam) and gloves. Cut each layer of glass on a 45 degree angle from the last so your layers form a cross hatch like x+x+x+. I also like to use aluminum flashing and partial paste mold release wax to allow me to apply additional pressure with clamps or weights. It’s not as good as wet bagging, but it is a hell of a lot cheaper.
LameBMX@reddit
while a 1" gash, hell a hole, wouldn't need support. for larger stuff you could tape the inside. or build a mold to lay the glass up against.then yes, the first layers are like a mold for the other layers to attach to. once the first layers have cured, rip out whatever held it in place, and grind away contaminants. then maybe apply a smoothing layer. but tape or a flat surface will leave it a bit proud on the interior. and just grind to shape basically.
since its a small vessel, you can use gravity to assist you in the layup. but the resin is pretty thick and sticky.
Ace-of-Spades88@reddit
What do you mean "you people?" 🤨
Candelent@reddit
The blowboat people, obviously.
checkoutmuhhat@reddit (OP)
Technically I mean fiberglass sailboat repairer people. But then also you people. Lots of amateurs that I want to ask this same question to cause I'm also an amateur in this specific thing.
Waterlifer@reddit
Depends on a bunch of stuff.
Typically on an outrigger canoe, the fiberglass will be thin (less than 1/4") and there will be no core. For a crack 1" long you can more or less feather the edges of the crack out a couple of inches with a grinder and patch it with a layer or two of fabric and epoxy. The crack may be longer than 1" beneath the surface, just keep grinding until you encounter sound material.
If there's core, you have to evaluate its condition, if it's rotten wood you have work to do, if it's sound you can just leave it for a 1" crack. For a larger repair you would replace like with like.
Cambren1@reddit
https://www.westsystem.com/app/uploads/2022/10/Fiberglass-Manual-2015.pdf