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Glen and all,
Would you agree that the Gougeon Brother's On Boat construction book, when discussing wood strip composites, talks only about small boats, canoes,etc? I think they mentioned that further research was needed and you have apparently done some of that. Also, MacNaughtons are the only people that I am aware who have done any published work on scaling up the scantlings that the Gougeons initially offered. I'm curious to know if there are any other published testing data that you know of? When scaling up to thicker strips, edge nailing is frequently used to hold things in place. I think MacNaughton mentions that the nails are not a structural element in the finished monocoque shell. I'm not disagreeing with what you are saying. But I just wonder how scaling from a canoe with a 1/4 inch strip thickness translates to a larger boat of, say, 3/4 inch thickness. It seems that most of the larger strip built boats have structural bulkheads which may come into play. Possibly bead and cove milling, rather than square edge strips might add enough sheer load resistance to warrant using yellow glue. My preference on small boats is to use epoxy with micro balloons to make sanding easier. Without the microballons the epoxy is harder than the cedar and is difficult to sand fair. But yellow glue works too and, at least on small boats, it is faster then waiting for epoxy to kick so you can lay more strips in a session. I've also tried powdered Plastic Resin glue but never had much luck with it since it does not really bridge gaps too well. Titebond II is definitely a Royal PITA to sand.Too rubbery. On one small boat I built I used epoxy to edge glue the strips. The hull seems very stiff and strong. But I have cracked the hull when hitting a rock. On another small boat I built I used yellow glue and the hull seems more flexible and has a "dead" sound when tapped. But I have never cracked this hull even though I've given it some rough use. It's also only 3/16 inch thick. Mabey flexibility is a good thing. Glenn Ashmore wrote: I just cannot believe how many people will do ANYTHING to avoid spending $50 for some epoxy. Enough 1/4" clear cedar strip for a decent size dinghy or canoe will cost you at least $500.00. Do you really want to risk that investment and your labor to save $40 or $50? The strips are not there just to hold the glass. They provide longitudinal stiffness. They must transfer shear loads between the two composite skins. And they must spread impact loads. Individual strips are not capable of doing any of those things. They have to be well bonded together so they can act in unison. Hot melt glue is not going to that. Liquid Nails might hold the strips together but the assembly will not be very stiff and fairing will be a royal PITA. You need a glue that maintains a tight stiff bond in a varying width glue line (gap filling), does not require high clamping pressure and that can be sanded fair without gumming up the paper. There is only one glue commonly available to amateur boat builders that will do that: Epoxy. Thickened epoxy is gap filling, bonds extremely well, requires minimal clamping pressure so staples are all that is needed and it fairs cleanly. Resorcinol would be a second choice. It would be a little less costly but requires careful fitting to eliminate any gaps and a lot of clamping pressure. Staples will not do it. You could only add one strip to each side per day. Same with polyurethanes only your total cost will be more than epoxy. There are people on this newsgroup that will advocate anything from wallpaper paste to curtain liner to save money but trying to save $50 on adheasive on a $700 project is penny wise and pound foolish. KR & CA Hunter wrote: Has anybody bought and built from a Compumarine plan? If so, could you advise your experiences? I would like my next boat project to be a cedar strip row/power boat and the John Clark plans look Ok on the web, but they seem a bit expensive for what are essentially a set of hull templates. Also, can anybody advise on what type(s) of glue are suitable for cedar strip construction. Builders adhesive has been suggested. Here in Australia the "Liquid Nails" product is sometimes referred to as builders glue. Does anyone know whether this is the same product? I would prefer to build without fasteners if possible, so any experience out there would be appreciated. Many thanks. Ken |
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