Dense Boat Building Douglas-Fir Weight

Discussion in 'Materials' started by abosely, Jul 10, 2015.

  1. whitecap alley
    Joined: May 2015
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    whitecap alley Junior Member

    Dense DF at 40 ring an inch is about 40 lbs a ft^
  2. abosely
    Joined: Mar 2015
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    abosely Senior Member

    I guess I put much unneeded info in my question & made it confusing.
    I'll try to rephrase it without unnecessary additional verbiage.

    Is the commonly listed weight of 32 lbs cu/ft for Douglas-Fir referring to the more common construction lumber that generally has closer to 8-12 rings per inch vs the dense pieces with closer to 20 rings per inch that is usually preferred for boat building?

    I'm just guessing that if the construction lumber is about 32 lbs cu/ft is less dense and hence lighter than the denser wood that is usually preferred for boat building.

    So wondered what dense (close to 20 rings per inch) D-F would be lbs per cu/ft.

    Just in general, not some exact weight.

    Cheers, Allen
  3. Jammer Six

    Jammer Six Previous Member

    Doesn't have anything to do with rings. Has to do with grades. And whether or not someone thinks air dry is dry.
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The construction grade stocks are usually farm raised and often a hybrid, not a true Douglas fir. These types generally have less rot resistance, don't have to fight for light in their life span, aren't stressed for nutrients or affected by natural events, like fire, insect infestation, animal habit, competition with other species, etc. These all produce trees that grow faster, though also typically and often dramatically alters their physical properties too. Most databases don't include the physical attributes of farm raised timbers.

    There is absolutely no difference between 15% moisture content, regardless of drying method. Moisture content is moisture content and all wood will eventually find its environmental equilibrium. Your bright enough to know this Jammer, even if you don't have the time to wait for it.

    Most boat builders have a need for raw and naturally seasoned stock, unlike the construction industry. This requires some forethought and planning, knowing you need to steam some stock, air dry others, etc.
  5. abosely
    Joined: Mar 2015
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    abosely Senior Member

    Ok thanks PAR, that's what I was wondering about. So the data is for natural grown D-F not the farm raised D-F that is the common light stuff.

    Cheers, Allen

  6. Jamie Kennedy
    Joined: Jun 2015
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    Jamie Kennedy Senior Member

    I suppose you might interpolate between these numbers and the other figure of 40 psf for 40 rings per inch and get about 35 psf for 20 rings per inch. The trouble is comparing one set of numbers with another is the accuracy of the moisture content and density measurement you might be comparing apples to oranges, but for interpolating versus extrapolating it might be a good guess.
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