OK, My comments will have [EA] around them
Here is some more clarification. These boats are made in 2 parts, left and right and glued together. Where they are glued together there is a flange about an inch wide so there is more glue surface. This seam is what split. The bottom line is that you have to reglue the flange together, then add additional reinforsement externaly
Wow. Looks like I'll be learning about fiberglass. Guess I won't turn in the library book by Vaitses. Here's some questions:
"grind through the resin rich glass without grinding too much of the fibers" I grind off the white gelcoat and get down to the caramel colored resin impregnated glass. Does the glass mesh have a thick layer of resin on top of it as well as in the void spaces between the mesh? Otherwise, don't see how I could avoid hitting the glass.
[EA] there tends to be a 1/16 or so layer of resin without glass beneath the gelcoat layer. Grind this off. Stop when you start seeing that you are cutting into fibers.
"where the crack is grind all the way down to the core" What's the 'core'? I guess I'd know when I hit the flange ;-) So you mean the fiberglass mesh?
[EA] At the exact centerline of the boat there won’t be a foam core, but there will be some filler. What you want to do is grind through about 1-2 layers of the glass. About 1/2 inch from the center you will see a little bit of the foam core exposed. This is OK for now. Take a putty knife and see if any of the gaps in the crack are big. The foam and flange Must be dry and clean. Clean the whole area with acetone and let it dry before proceding.
"Cover the sucker and heat it if you can to dry the core and the split in the flange." Looks like I'll need to clear the garage. Or I could put a clamp or 2 on the hull to open the crack a bit, then use a hair drier? I also read someplace where they had stuff that would cure underwater. Not sure if this was epoxy or polyester. It would be hard to tell if the crack was dry inside.
[EA] Make sure it is clean and dry before applying the epoxy or it will not work well at all. Make a little tent with plastic around it and buy a 10 dollar electric heater. This will do the trick.
"inject epoxy with microballons" The cracks are hairline, maybe as thick as your fingernail. I've got some syringes and maybe could use one. I've also heard of mixing microspheres with Cabosil.
[EA] Syringes work very well for this. Cabosill makes the epoxy not run as well, microspheres(microballoons) provide strength but it still flows well for injecting. Cabosill has a lot of good uses, just not here.
"Release cloth" What's this, a dry strip of glass?
[EA] Release cloth is a coated nylon fabric that epoxy can penetrate, but won’t stick to at all. It allows you to get all the air bubles out when laminating fiberglass with epoxy and also prevents having to deal with amine blush.
http://www.westsystem.com/ can give you more info about this if you are interested.
"use non air inhibited Gelcoat" With polyester resin? I thought polyester didn't bind to epoxy. But the other options would be to paint the epoxy?
[EA]Here is the deal as far as I am concerned. Gelcoat won’t bind [chemically] to epoxy. It will bind mechanically. This is why I leave the underlying epoxy and filler rough ie 80-100 grit. So far this has always worked well for me. I have done many of these repairs. You can paint the gelcoat on in 4-5 layers then wetsand it into the surrounding surface. Mix a small batch, paint it on. Wait for it to tack 10-20 min if it is warm say 70-80 deg. Mix another batch and repeat. Do this 3-5 times and you have a nice thick layer. Don’t let the gelcoat harden too much or the next layer won’t bond chemically. Then just let it dry for a day or 2 and you are done.
You can do the whole repair in 4 evenings.
Last few questions:
What type of mat would you use?
[EA] I would not use mat. You can by fiberglass tapes that are 1,2,3, etc inches wide from marine stores. The best stuff to use is S glass, but the more common E glass is ok also. Or you can get a large piece of cloth and cut it in strips. This is cheeper but harder. Note: Fiberglass cloth is much stronger then the same weight of cloth. I recommend against using mat for structural repairs.
Also, since I've already epoxied over this area, could I put on another thicker coat, maybe with milled glass filler or something and see how it holds? I wouldn't want to get into an unsafe situation on the water, though.
[EA] Generaly, I think the earlier you fix it the better off you will be. The longer the water soaks in the worse the problem will be. Even if the boat is watertight today, eventually the split will get worse.
Good luck
Eric
