Quality of wood

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

  1. bajansailor
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    bajansailor Marine Surveyor

    Mr D, the bloke in India has already built a Euro 2150 motor yacht as per my post above - and from the photos seen he has done a pretty good job.
    If you take into consideration that building a second boat to the same design should be much easier for him (if he is interested in taking on another project of this magnitude) then maybe your best bet would be to ask him to build it for / with you?
    This might well work out a lot cheaper in the long run, compared to you building it in the UK (I presume that is where you are planning on building it?).
    Especially as you will most likely have to employ people to help you (and UK labour rates are significantly higher than those in India).
     
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  2. TeddyDiver
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    TeddyDiver Gollywobbler

    If there's a bug problem dump that timber and get some without, besides kiln drying doesn't prevent bug infestion after. Of course kiln dryed can be used but a couple years additional air drying solves much of the kiln drying problems. The major problem with kiln drying is the timber continues to shrink afterwards as it's not just the general water % but there's water and natural ether inside the wood cells too which needs longer time to eveporate. If building with timber prone to and where bugs are an issue other means. like monoethyleneglycol should be used..
     
  3. rwatson
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    rwatson Senior Member

    "natural ether inside the wood cells too"
    Huh? what is this mysterious substance?
     
  4. TeddyDiver
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    TeddyDiver Gollywobbler

    :D no mystery, Wood is more than cellulose, about 50% being other organic compounds, the stuff holding the wood cells together, lignine. The stuff which makes the wood smell wood. Stockholm tar is made of that stuff and wood terpentine. Whatever you want to call it...
     
  5. rwatson
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    rwatson Senior Member

    Since when is Lignin a "natural ether "?
    Also, it's just as subject to drying as the cellulose, and may even dry BEFORE the cellulose.

    " The process of kiln drying will harden the lignin (the stuff between the cell walls in wood) and set it in place. While the wood will still take on moisture and expel it, the cell walls are not as flexible and thus the wood will not move as dramatically. In essence, kiln drying reduces the wood’s ability to move making it more stable.

    Setting the lignin like this can have drawbacks if done too quickly however. This is called case hardening. When the wood dries the outer layers dry faster than the inner layers. If the outer layer “sets” up too fast it creates a hard shell around the inner layers and traps the moisture inside. This wood is very unstable and will move dramatically when cut. Cracking and discoloration will occur on the outer layers and is usually a sign that case hardening has occurred. Kiln drying is a fine line that can go very wrong if done too much and too fast."
    Wood Moves No Matter What We Do To It, Drying Can Help https://www.mcilvain.com/lumber-drying-process/
     
  6. TeddyDiver
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    TeddyDiver Gollywobbler

    Believe that you may but that's only what they teach for engineeers in school, not the reality :)
     
  7. Rumars
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    Rumars Senior Member

    Rwatson why are you giving the poor guy a hard time? You know very well he is talking about sap sugars even if he words it wrong. But thank you for explaining case hardening.

    It is universaly known that wood should only be felled in winter one day before the new moon, let in the forest for a week with the branches on, then submerged in water for a time prior to sawing. Air drying should be for as long as possible and before final fitting it should again be aclimatized to it's final destination climateric conditions.

    All of the above is of course completly beside boatbuilding.
    Traditional boatbuilding uses green wood because boats get buildt quick and stay in the water from then on, no need to properly dry it for years. Shaping green wood is also easy on the tools and the often employed steaming is a form of technical drying anyway.

    Wood - Epoxy boatbuilding is best with moisture contents under 12% and that is not achievable with AD (unless one builds in a desert). Most people don't have the possibility to climatize the wood during the build to those levels and adjust the epoxy to suit anyway.
     
  8. TeddyDiver
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    TeddyDiver Gollywobbler

    No worries Rumars, Rwatson knows something but he doesn't know what he doesn't know. Of course words can be decieving and in some parts of the globe some words are understood differently, and even more so among native speakers. Woods have so many different organic hydrocarbon compounds that it's a specific science which studies the subject (incliding the how to process them) so it's no point to try to name them here.
    Anyway what comes to kiln drying it's not even close to the temperature for setting lignine, that's another method (heat treatment) which improves the rot resistance and reduces the affects of moisture to dimensions. The unwanted side effect makes the heat treated wood prone to fail unexpectedly under loading.
    Anyway I use in my work kiln dried wood daily basis and I quarantee it shrinks, twists and checks...
     
  9. bajansailor
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    bajansailor Marine Surveyor

    I wonder if DWilson is still with us?
    He has been very quiet.
    If you are still here D, what are your thoughts on talking to the chap in India about building another one of these big motor yachts?
     
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  10. Dejay
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    Dejay Senior Newbie

    Ok hold up, is this serious or are you kidding? :)

    Interesting discussion about wood. On a side note there is short video about a new advances in artificial wood with lots of links about wood in the description I'll have to read one day.
     
  11. fallguy
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    fallguy Senior Member

    "Who told you to build your epoxy boat with green wood?"

    "Some forum member on boatdesign.net."

    "Then what happened?"

    "boat rotted from the inside"

    really guys....

    green wood is never encapsulated
     
    Last edited: Nov 4, 2019
  12. rwatson
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    rwatson Senior Member

    Yeah, like the quote

    "This is called case hardening. When the wood dries the outer layers dry faster than the inner layers. If the outer layer “sets” up too fast it creates a hard shell around the inner layers and traps the moisture inside. This wood is very unstable and will move dramatically when cut. Cracking and discoloration will occur on the outer layers and is usually a sign that case hardening has occurred. Kiln drying is a fine line that can go very wrong if done too much and too fast.""

    Rwatson knows "patronizing", so please start providing some trusted commentary instead of making stuff up like "organic hydrocarbon compounds" as if it had anything to do with the correct drying of wood.
     
  13. Rumars
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    Rumars Senior Member

    Why would I be kidding? That's the way it was done traditionally in temperate climates. The tree has the least amount of sap flowing in winter, and floated wood dries better, presumably because water dilutes the sap. The log is also less likely to split if it stays wet before sawing.

    But as I said it has little to do with boatbuilding. Traditional boatbuilding, and here I mean the kind without epoxy or any other glue, used mostly green wood. Dry wood was only used when the wood was imported because that's how it arrived. Modern times it's different of course, AD wood is usually more expensive than KD and green is only used for bending. Compass timber (wood grown in natural curved shapes) used to be common, now it's speciality.

    Epoxy boatbuilding needs dry wood, the dryer the better.
     
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  14. Howlandwoodworks
    Joined: Sep 2018
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    Howlandwoodworks John Howland

    Saving money on a yacht seems to be an oxymoron.
    I believe you are looking for empirical data or posteriori knowledge on building a yacht, me too.
    Here is a document from the US Navy on wooden ships construction.
    Wood: a Manual for Its Use as a Shipbuilding Material https://books.google.com/books?id=4LosAQAAMAAJ&pg=RA3-PA141&lpg=RA3-PA141&dq=scarf+joints+White+oak+below+water+line&source=bl&ots=ClpxuO-0QY&sig=ACfU3U1wWs_hv4InqLinYLbOoet_2kqHVw&hl=en&sa=X&ved=2ahUKEwin16-ExIvlAhUEx1kKHYPtBpwQ6AEwGHoECAYQAQ#v=onepage&q&f=true
    Best of speed on all of your endeavours.
     
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