Particularly on a vertical surface.Īctually I find 1700 easier to work with. Then use thickened epoxy to bind them together. Wet out the areas to be glued ahead of time with neat epoxy. This is not an appearance grade repair anyway, is it? Isn't it back behind the settee? My preference would be a 3/4" sheet of plywood (glued back together with a scarf joint) wrapped with glass.Īny wood joint you use, whether butt, scarf (which is a modified butt actually) needs to be done with thickened epoxy. But I don't understand your concern with getting a flush surface. If the only area you're replacing is that rotted out hole down at the bottom, either joint will probably do. Essentially with your butt joint you're trading a 3/4" sheet of plywood for a 3/8 and then wrapping it with glass. The scarf joint is stronger than the butt joint you describe. Polyester dissolves the adhesive that holds the mat strands together (this is the intended result). Also, mat is incompatible with epoxy unless specially made to be epoxy compatible. The mat adds unnecessary weight and bulk. Thanks for the feedback, I really am formulating a plan and modifying it based on your advice in addition to what I can gather from other sources.ġ708 cloth consists of two layers of 17 oz biax with a mat backer. I'm also thinking that if I can position the new bulkhead section properly, would a 4" scarf joint utilizing an unthickened epoxy on the joining surfaces, then maybe a wider layer of fiberglass (around 30") be just as strong? From what I've read about epoxy, would a slightly thickened (high density filler) epoxy be pushed into the joint (from the head area) between the two pieces of ply forming the bulkhead, and soon thereafter laminate the fiberglass/epoxy to the correct thickness? Then repeat on the aft side? My understanding was that scarfing (let's use the 4" example) would cause an overlap of approximately 4" and a bevel was like a butt joint except that it was only for the center 3/8" of the 3/4" plywood, and each section of the plywood was sanded out at an constant angle to 6-8" on the forward and aft faces of the plywood to give the laminated layers of fiberglass and epoxy room to build up resulting in a nearly flush repair. Maybe I'm a little confused about the beveling vs. I figure I've got about 75 days to become an expert before I start gluing up the new section of bulkhead. I've got a boat restoration acquaintance I'm going to order the marine ply from and hopefully pick his brain as much as possible before he starts charging me. I'll see about ordering that from defender marine, unless I can find a local supplier. I've already got the pumps for west system, so I'll stick with that, but the 1708? fiberglass cloth looks like it's made by MAS. I've been reading up on West System's guides and some old wooden boat magazines. I have used epoxy before, but not on this scale, and not vertical. That's kinda where I was headed, but it's nice to hear confirmation. My sole supplier for West System resin and fiberglass is. Most of it you'll find in hardware stores is designed for bodywork, and contains an finishing chemical that works with polyester but is not compatible with epoxy. I've found the value-add material West has published over the years (epoxy repair techniques, EpoxyWorks magazine, etc) to be so useful that I'm happy to pay the premium and have never had a problem with any of their products.Īlso, you have to be careful when buying fiberglass cloth. We can certainly debate whether the premium charged for West System is worth it (there are other manufacturers, including System Three and Raka, probably others) but the only use to which you should put polyester after the boat pops out of the mold is gelcoat repair. Polyester is OK for building standalone structures (it is after all what our boats are made of to begin with) but it does not have the adhesive ability or strength to use in any structural boat repairs whatsoever, whether that's to wood or existing polyester.Įpoxy is the only way to go.
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