Cedar for "coring"

Discussion in 'Materials' started by adamanderr, Aug 24, 2008.

  1. adamanderr
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    adamanderr Junior Member

    newbie question, i tried searching for cedar as a hull building material it seemed positive but vague. is there a good thread one just cedar, types, applications, painting it, epoxies etc?
    I was thinking Carolina skiff style. strip with cedar core, glassed on either side then painted??
    I have only been considering such a big project because my neighbor has a sawmill mill and just sourced alot of big local trees, pennsylvania. I don't know much about the difference in cedar and assume it should be cured well.

    also where to find that much fiberglass and epoxy? and whether i could afford it. price ranges?
  2. TeddyDiver
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    TeddyDiver Gollywobbler

    Considering the timber you got to wait/look some "local" expertice. There's a lot of variety in timber allthough it might be the same species but the quality isn't. Thou I think you got to give more information.. Just PA isn't enough. It's also different quality for strip canoe vs 40' cruiser..
    The prices vary somewhat (esp epoxy with these chancing oil prices). so best to check resellers. Google epoxy with West, Elephant or some other brand to find additional info.
    If you get the timber with reasonable price and selected:D make a deal. Ask how to store them to dry (a couple of years at least) Then you have time to read a couple of books of boatbuilding, hang a round here:) and plan the project..
  3. Ilan Voyager
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    Ilan Voyager Senior Member

    A good source for resin and fibers is Raka (www.raka.com). Larry is very helpful and has a lot of stuff, so you'll find almost every thing with one provider. I have used his basic resin with tropical hardener with very good results.

    Shelf life is incredible in our Yucatan peninsula climate; more than six years. Resistance to ultraviolets is very good, easy to apply and sand, glues perfectly a lot of materials. Brief good stuff at good price.

    For the core I've found that any straight grained light wood works. The basic requirements are good ratio weight-stiffness, no knots and good gluing, and stability. Rot resistance is a plus, but in some applications like kayaks stored indoors isn't necessary.

    A lot of pines and cedars are good candidates, some tropical "hardwoods" when very light will work. Here I use "cipres" (cupressus lusitanica).

    The wood must be perfectly dried. It's easy with strips less than 1 inch thick and done in a few weeks in summer. The strips must be quarter sawn.

    Have a look in your local provider. In Europe the nothern pine (a very light white pine ) gives excellent results.

    Strip plank gives very strong and sound hulls with reasonable work and limited tooling. As you want to paint you can use maple flour a cheap and strong filler. An automobile acrylic paint works very well.
    Last edited: Aug 29, 2008
  4. alan white
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    alan white Senior Member

    For years red cedar from the Pacific Northwest has been recommended for strip-building but I don't know why any epoxy-encapsulated boat (especially if dry-sailed) couldn't be built of spruce. There's a reason masts are built almost exclusively of spruce (never cedar).
    Around here (Maine), getting knot-free spruce is easy. But if you must use kiln-dried spruce, you can rip some nice vertical-grain from planks form Home Depot.
    And how would this spruce compare to much more expensive cedar?
    At nearly the same weight, it would have greater cross-grain strength and also stiffness. Martin guitars have spruce tops--- not cedar. They used to use the same Sitka spruce that masts are made from. Now they use, I think, mostly Adirondack spruce.
    If I build a stripper, I'll use an Eastern spruce, probably air drid (but again, kiln dried is nearly as good).
    What about rot??
    Here's the deal: at least with glued and glassed strips, each individual strip is hopefully seperated from it's neighbors by a waterproof membrane (usually epoxy). It's difficult to imagine that rot would be an issue ever except in cases of absolute neglect (based on the common knowl;edge that cedar is more rot-resistaqnt than spruce).
    Certainly use cedar (better Eastern white than Western red) if building with nails rather than glue and glass. Without very constant and thoughtful maintainence, spruce will not do well. But add epoxy and glass, and you'll begin to realize the benefits of spruce over cedar just like Howard Hughes did when he flew his Spruce Goose, or thousands of sailors who still prefer spruce over any other wood for spars.

  5. Ilan Voyager
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    Ilan Voyager Senior Member

    I agree totally. A light pine like spruce will do the task perfectly.

    I'll add that epoxy strip plank with fiberglass skins gives very strong and durable boats. Some have 30 years now with no problem.
    The method allows to make virtually any boat shape at a good price with little tooling and common skills, with very neat inside hull easy to keep dry and clean. Difficult also to make big mistakes as the process is by steps (have a problem while infusing a composite hull and you'll have a very big bill...)
    Easy to engineer also as delamination problems (common with composites) are easy to solve. The most common mistake with strip plank is to use too strong and so too heavy scantlings; the method when well engineered can give very good weights not far from advanced composite methods.
    Indeed it's a very good method for the backyard builder and the one off pro boat builder.
  6. rwatson
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    rwatson Senior Member

    How did we get onto spruce?

    The guy is looking at 'cedar'!

    The only problem I can think of is if the wood is too oily - and wont take epoxy well. That can be the case with some cedars.
  7. alan white
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    alan white Senior Member

    Cedar was positive but vague.
    Spruce is the better choice for many reasons (ever split cedar and then spruce? Spruce doesn't split nearly as easily as oak because it has exceptional cross-grain strength). Cedar solits a lot easier than oak.
    Does this matter? Yes, if you want a stiffer and stronger boat.
    Now price both cedar and spruce. Note how spruce is available practically everywhere for 30-40 cents a board foot.
    How much does cedar cost?
    Finally, regarding the rot problem, use cedar to plank a carvel hull, but if sealing with epoxy and glass, compare with cold-molded, where many easy-rotting woods are used (recently I heard of hard maple, which rots if it even looks at water).
    Nobody even mentioned the rot issue, only structural issues.
    It's really a matter of habit, because, I think, in the early days of glass/epoxy strip-building, cedar was no doubt a way to hedge your bet that the epoxy would keep the core dry. Now we know it does, and people still seem to home in on cedar almost exclusively when they think of building a stripper.
    No, there's no problem with cedar, except it oughtn't be considered the only choice when building a stripper.

  8. Gashmore
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    Gashmore Junior Member

    Might consider white cedar (Swamp Juniper in the low country) . Much easier to get on the East Coast. About the same density as western red but a little better impact resistance and less resinous so it takes epoxy very well.

    Built my hull in white cedar/epoxy/glass and the white cedar was a joy to work with. 'Course at 45' LOA I couldn't call it a Carolina Skiff. :D

  9. smithn00
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    smithn00 New Member

    Do you all have a source for 1/8" spruce veneers for cold molding? I need about 200 sq. ft.
    If not, what veneers are used for cold molding today and where can I get some?
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