Douglas Fir Bowsprit

Discussion in 'Materials' started by raincoast, May 14, 2012.

  1. raincoast
    Joined: May 2012
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    raincoast New Member

    I recently had a new bowsprit made from douglas fir. After less than a year one side has become very light and opaque, with loss of colour and grain texture. The attached photo shows the effect. I'm used to douglas fir growing darker with age, but not this very rapid change. Does anyone have any suggestions as to why this has happened?[​IMG]
     
  2. raincoast
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    raincoast New Member

  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The laminate, which appears to be 3 pieces shows two on the right with nice looking, tight grained stock, but the left most section of this laminate (hard to really see) seems to have a flat grain, compared to the vertical in the other two and it's likely juvenile wood too. What is the density like when poked? It's entirely possible someone sold you some other species and called it Douglas fir. A number of species are now all lumped into the Douglas fir/western larch basket. Also judging by the rail next to it, the sprit obviously needs UV protection, so some repairs and coatings are in order.
     
  4. raincoast
    Joined: May 2012
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    raincoast New Member

    The bowsprit is virtually new. The area that is lighter and has lost texture is south facing when the boat is on its berth, thus it appears to be a UV reaction. After construction it had two coats of epoxy and five coats of varnish. All the other douglas fir I've seen and had used on the house has darkened over time, so I'm trying to work out what has happened in this case.
     
  5. alan white
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    alan white Senior Member

    Paint it---- problem solved.
     
  6. Petros
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    Petros Senior Member

    Discoloring of the wood due to sun exposure does not affect the strength, it is a reaction of the pigment of the wood to UV light. If there is no moisture intrusion or structural damage (that caused the color change), there is no issue other than appearance.

    There is a condition where the raw lumber may have been damaged in transport or handling before bowsprit was made. The grain gets crushed, and it may cause it to take finish or stain differently than the undamaged wood. You can not tell by looking at the raw lumber that it is damaged, parts can be made from it and no one will know until it fails.

    Presumably if they bought quality rated marine lumber, this kind of damage should not be in the wood. It required examining the wood under a microscope to see if the wood cells are damaged due to cross grain compression. I kind of doubt this is the problem with your bowsprit, but it might be worth getting some knowledgeable about compression damaged of wood to examine it with a hand held magnifier. Or you might load it to 60 or 70 percent of the design load and verify it is sound.

    Good luck.
     

  7. alan white
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    alan white Senior Member

    The odd piece out is not lighter due to sunlight. The change wouldn't be at the joint but would be gradual. Often, fir is quite light, especially young growth or sapwood.
    If you must keep it varnished bright, bleach and then stain the whole thing. The stain will pull together the shades somewhat. Time will do the rest as everything darkens.
     
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