Quality of wood

Discussion in 'Materials' started by Dwilson83, Oct 31, 2019.

  1. Dwilson83
    Joined: Sep 2019
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    Dwilson83 New Member

    I am currently pricing up my materials list for a boat build, a Bruce Roberts euro 2150 in wood epoxy. For this I require a lot of Douglas fir, I noticed that if I was to purchase Douglas fir fresh sawn green and that isn’t kiln dried and hasn’t been planed opposed to Douglas fir kiln dried and planed all round the price is roughly 90% cheaper. obviously with a lot of work having to plane it myself and air drying it. I could save tens of thousands.
    Now obviously I understand that if it’s not kiln dried and only air dried cracks will appear on the surface of the wood. My question to you all.
    If I was to air dry it properly making sure it has completely dried out then if I was to use west system wood epoxy filler to fill all cracks, would this structure be just as strong as using kiln dried Douglas? It will be getting at least 1 layer inside and 1 layer outside of 10oz fibreglass aswell.
    From a lot that I’ve been reading most of the time epoxy fillets, for instance, end up being stronger than the wood itself. So is there a possibility by saving lots of money and doing it this way we could end up with a stronger structure.
    Has anyone tried this before? If so what were your results?
     
  2. bajansailor
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    bajansailor Marine Surveyor

    I don't know enough about the pros and cons to offer an opinion, but I am sure that there are many on here who do.
    So I googled the Bruce Roberts Euro 2150 - wow, that is a very impressive (and massive) motor yacht.
    EURO 23, STEEL KITS POWERboat boat building boatbuilding boat plans kits sailboats trawlers powerboats steel aluminum fiberglass Boats, maker for sale dealer design boats wooden boats boatbuilding books sail cruising, yacht yachts Bruce Roberts Yacht Des https://www.bruceroberts.com/public/HTML/EURO2150.htm

    And here is the article in Epoxycraft
    Building a Bruce Roberts in India - Epoxycraft https://epoxycraft.com/westsystem/building-a-bruce-roberts-in-india/
    Roberts Euro 2150 - 1.jpg Roberts Euro 2150.jpg
    Will you be building her yourself, in the UK?

    Edit - I just have to ask this question - what made you change your mind from building a power cat?
    Advice on multihull design https://www.boatdesign.net/threads/advice-on-multihull-design.62854/

    I really admire your optimism, and enthusiasm for still wanting to build a HUGE boat, especially after considering the good advice given in your previous thread.
     
    Last edited: Oct 31, 2019
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  3. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Dwilson83
    You won't save anywhere near 90% by buying green. To the base price add;
    Years of storage.
    30% loss due to worpage and checking (cracks)
    50% of stock turned into sawdust
    The labor, tooling and worn out blades to surface the dry wood.
    The cost of having a facility to process the dry wood.
    The electric bill

    Kiln dried lumber might be nine times the cost of green stick. But the supplier doesn't make nine times the profit. It is nine times the price because it is nine times as expensive to produce.

    If you think you'll save by buying raw wood, then go all the way and buy a chainsaw and fell your own trees.
     
    Last edited: Oct 31, 2019
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  4. Yellowjacket
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    Yellowjacket Senior Member

    Bad idea.... If it isn't dried and planed it isn't going to be stable and is going to want to warp like all get out as it dries. After you screw down the planking it's going to try to twist and warp as it dries. You would have to go back and sand the surface to get it smooth enough to be presentable after it is done and finally dries. The outside surface being glassed with 10 oz isn't going to be sufficient for a boat like that. You need a thicker skin since you're going to get more damage from hitting things and being rubbed against things like docks. You really need at least twice that thickness of glass to provide a more robust skin. I would consult with someone who's done this type of boat using planking and glass skins before you go out and spend a ton of money and find out that what you have won't last. To that end I'd think about using mahogany as it's more rot resistant than fir. You're going to spend a lot of time in addition to having a huge investment in this project and if you aren't careful you could end up with a white elephant when you are done.
     
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  5. fallguy
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    fallguy Senior Member

    Lumber is perhaps one of the trickiest buggers around.

    Air drying lumber can result in insects. Powder post beetles will eat the wood and are killed by kiln drying at high enough temps to kill them.
    Air drying lumber will result in warpage
    Air drying lumber too fast will result in more warpage.
    Air drying lumber too slow will result in moldy lumber.
    After air drying, you will need to joint and resaw every board or they will be too warped to use.
    Air drying is typically done on rough lumber, this is followed by planing, then edging with either table saw or joiner, then joining, then typically resawing to square. Oftentimes, after you edge the lumber, is moves again.

    Flat sawn lumber is not as stable as clear vertical gain lumber, but generally stable enough to build with.

    Do not purchase green lumber. I have read numerous horror stories of builders using lumber that was a bit wet and it literally rotted from within after encapsulation in epoxy. Can you imagine such a horror as using improperly dried wood for you hull framing?

    Typically, the designer will spec a few option of lumbers that suit. Use the least expensive.

    Another way to save money on lumber is to go select lumber at a yard that allows it, like a retail place. You can spend the entire day looking for knotless lumber or nearly no knots.
     
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  6. Mr Efficiency
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    Mr Efficiency Senior Member

    What about old demolition timber ?
     
  7. Rumars
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    Rumars Senior Member

    Nobody in his right mind buys dimensional PAR lumber for boatbuilding. Designers provide finished lumber dimensions but it is your business how to get there. On a project this size wood is cut to order and epoxy is by the barrel. How you dry the wood is not relevant. For epoxywork the wood must be at 12% or less moisture content.

    Example: let's say the designer specified 35mm strip planking followed by 3 layers of 4mm cold molding. The strips can be square or profiled, either bead and cove or tongue and groove ("Speedstrip"). The normal aproach is to buy 2 inch rough flat sawn KD flitches and machine the strips out of it. Now who does the machining depends on the available machine park and labour, a specialized outfit can do it quicker and better.
    The 4mm veneer is sliced or sawn by a specialized outfit directly from the log acording to the specified grain pattern.

    The best money saving strategy depends on the specific circumstances. Air drying is such a thing, if you already own a big airy barn that sits empty and have 2 years to spare it saves money, if not youhave to pay for the drying.
     
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  8. rwatson
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    rwatson Senior Member

    All good responses so far. The only point I can add is, if you are trying to "save money" by increasing the amount of Epoxy, then you are chasing your own tail.
    Any time you need to replace wood with Epoxy, you are emptying your pockets.

    The thing is, you can spend less on a hull using high-density foam, Polyester and Glass with vacuum application, than Plywood and Epoxy. Then you end up with a rotproof solution lighter than any timber build.
     
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  9. fallguy
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    fallguy Senior Member

    I have used 250 gallons of epoxy in my build and the cost is about $100 a gallon.

    If I was not building in an attached structure to my home, the best way to save money on the build would have been using an ester. No wood in my foam build.

    I budgeted 130 gallons of epoxy at $15k, so I saved some per gallon, but the epoxy was a major miss as I underestimated waste. I am vac bagging..and probably running a bit high on hand taping..

    Both Rumars and Watson make good points. You need to be able to purchase lumber in wider sections. If the designer specifies 3/4" x 1 1/2" lumber, you would purchase 1x6 or 1x8 lumber, preferably KD. Then if you are building a cat; you only rip enough for that part of the build you currently need and you also want to use shrink wrap or twine and retie bundles of the stuff to keep it from moving bad on you as it dries or releases tension. Typically, you would purchase a thin kerf blade at 0.06x" and then if you are using 1x8, which is actually 3/4" thick by 7 1/4" wide, you would try to get four rips from it. Of course this assumes your spec is 20mm x 45mm. Money is saved this way. There is no reason to PAR the stuff; it is actually better with sawmarks for gluework. And buying thinner wood straight is damned near impossible unless you buy VG.

    Ripping lumber is part of the build.

    If your spec is for thicker materials, you may need to rip from 1.5" materials, etc. In that situation; you hope to yield out something from the offcut, but may not. So say your spec is 35x45.. Then your cuts are still 1 3/4" wide and you turn them and rerip or use at 40 above spec, although that will drive weight. Generally, the designer would have build realities in mind.

    If you are unsure about how to best yield, give your specs out here if the designer allows.
     
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  10. Rumars
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    Rumars Senior Member

    Let's keep in mind what we talk about here. It's 70' long, 21' wide, has 3' draft and beeing a motorboat only god knows how high the sides and superstructure are. You are looking at 3-5000 sq.ft. of hull, maybe more. Maybe the OP will give us the skin area and thickness so we know exactly.

    It's a build were wood is bought by the truckload and one has to think about owning a forklift, paying for sawdust disposal, etc.
    Yes one can save significant money buying green lumber but the circumstances have to be right. In Europe usually the cheapest price for wood will be logs "free forest road" where quality DF is around 100-110€/cubic meter. That's 28 cents/board foot for americans. From here you start to add transport, handling, sawing, drying, grading, etc. After all this it's around 1000-1200€/cm at the sawmill. So in theory you can save 10 times the price, in practice not so much. We are going to disregard the ocasional incidence of "cousin economy" where everything is measured in sixpacks/cm.
     
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  11. fallguy
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    fallguy Senior Member

    He ought to be ordering like KD S2 or S3 from the mill then.
     
  12. gonzo
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    gonzo Senior Member

    The high temperature of the kiln kills the spores of the mold and yeasts. That makes kiln dried lumber more durable.
     
  13. TeddyDiver
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    TeddyDiver Gollywobbler

    Ok, a lot misconseptions etc..
    First. Air dried is allways way better than kiln dried. Thou you can't air dry in moist environment so if the weather is not favourable it's done in climate controlled space.
    Second. Boats of that size are not DIY, never. They are comissioned.
     
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  14. fallguy
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    fallguy Senior Member

    Air dried is not 'always' better. Sorry, but that is simply wrong and you argued against it in the very next sentence. In the simplest of problems, air dried lumber does not kill post beetles. You could theoretically build a boat full of beetles that would eat and eat. If you had less than full encapsulation; they could life cycle for Pete's sake!

    The balance of your post is right. A boat of this size requires lots of labor and coordination. A boatyard would be needed. Finding capable labor is really its own challenge.
     

  15. Rumars
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    Rumars Senior Member

    TeddyDiver is right. KD affects the mechanical properties of wood compared to air dried. But sometimes KD is the only option and sometimes it's even required.

    Anyway we should all be aware this discussion is just for fun. In real life the price savings between buying green/dried lumber vs. buying SpeedStrip would not keep the two 800HP engines and the generators running for very long.
     
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