Chris-craft construction

Discussion in 'Boat Design' started by Stavbergen, Apr 29, 2019.

  1. Stavbergen
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    Stavbergen Junior Member

    Hello I was looking at the old Chris-Craft boats and I can see at the stem they have 3 seperate peices joining down to the keel. The knee, stem and gripe? Whats the idea behind this? Is it to do with expansion? Why not just cut one peice for all and join to the keel? Just wondering?
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Any picture ? One assumes it is because the strength in the timber has to take into account the grain direction, plywood is an attempt to get around that problem.
     
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  3. Stavbergen
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    Stavbergen Junior Member

    I cant find the pic now. It was on google images. I had the same thought why not just use plywood, I even looked up when plywood was invented to see if it was available at the time. It was invented but not sure if it was readily available. So plywood could be a good substitute?
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Not necessarily, it depends on the magnitude of the load, and the direction. Frame members made from ply are less effective in many cases, because the direction of the grain, is out of whack with the load, for half of the wood in the ply. Ply is basically best suited for paneling, not frames.
     
  5. Stavbergen
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    Stavbergen Junior Member

    Cool thanks
     
  6. gonzo
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    gonzo Senior Member

    Which model are you looking at. Is it one of the 1950's bullnose Constellations?
     
  7. fallguy
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    fallguy Senior Member

  8. Stavbergen
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    Stavbergen Junior Member

    Hi it was the 1946 sportsman. I'm limited with timber options in Australia. So I was wondering about alternatives. I have roustabout plans from glen l and its mostly plywood. I was wondering why chris craft need heavier timbers? Cheers
     
  9. fallguy
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    fallguy Senior Member

    You won't enjoy rabbeting plywood unless you can do it with a router.

    Keep that in mind.

    Heavier timbers are also less prone to breaking when solid wood. But I would avoid making things much smaller just for build ease.
     
  10. gonzo
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    gonzo Senior Member

    Those boats were built of Philippine mahogany (sometimes called luaun)
     
  11. Rumars
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    Rumars Senior Member

    To answer your original question you have several pieces at the keel-stem intersection because of grain runout and the loss of strenght. One piece solutions are grown crooks or laminated members. Both solutions were known to the builders at the time. They probably determined it was not economic to use them.
     
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  12. Stavbergen
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    Stavbergen Junior Member

    Cool thanks for the responses
     

  13. Rumars
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    Rumars Senior Member

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