Chine log (First Boat)

Discussion in 'Boat Design' started by Green horn, Oct 8, 2012.

  1. Green horn
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    Green horn Junior Member

    Having trouble figuring out the cuts that need to be made on my frames for my chine log to fit properly. I am building my first boat a 18ft Carolinian Dory Spira design with 2/4 frames 29 and 1/8 apart lap joint
     
  2. Green horn
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    Green horn Junior Member

    Also it is a flat bottom
     
  3. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    Flat bottom chine logs are the easiest to make. Are you building upside down? The Carolina dory has it's chine log fitted into notches in the frames. Notch the frame so the height of the log fits the frame at the inboard lower corner, which will leave the outboard lower corner standing proud. Fit it so the outer face of the log is flush with the frames. Next go back and knock off the corner that's standing proud, so it's flush with the bottom of each frame. That's it.

    The easy way is to take a scrap piece of chine log, say a couple of inches long and use this as a tracing template to draw on the frames. Again, set it flush with the sides, but let the outside corner hang out, with the inside corner being flush with the bottom, then whack off the exposed corner of the chine log until it's also flush. This will make a bevel on the bottom edge of the chine log.

    The drawing shows a typical chine log on a flat bottom. The far left is the lower corner of a frame, without the log notch, the middle has the log notched in, but the outboard corner is standing proud, the right hand image has the log bottom trimmed flush.
     

    Attached Files:

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  4. Green horn
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    Green horn Junior Member

    Yes I am building upside down and thank you for the info but my problem comes in when the chine log runs bow to stern do my frames need to be angled wish I could describe it a little better

    ok say you built your frames on a strong back cut the keelson out installed the transom and stem then you just lay your 1x2 along the edges of the frames it almost looks like I need to cut my 3/4 x 1 an 1/2 at different angles (for each frame) to keep the rounded shape of the chine log if i just cut the frames straight looks like I'll have flat spots where each frame is.

    THANK YOU AGAIN PAR
     
  5. Green horn
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    Green horn Junior Member

    Do I need to buy a book (Boat Building for Simpletons) ha
     
  6. PAR
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    PAR Yacht Designer/Builder

    The bevel on the bottom of the chine log "rolls" which is it changes it's angle along it's length, but you can address this using a straight edge from the keel batten to the chine long. A few saw kerfs to the required angle and connect the dots with a plane.
     
  7. philSweet
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    philSweet Senior Member

    Yes, Green horn, you do that. When erecting the frames, they are placed in front of the station mark forward of the max beam and aft of the station mark aft of max beam. That way you have something to trim off to make the planking lie flat. If you did it the other way around, you would have to fill a void to put the planking on the proper offset. The notch for the chine log is similarly bevelled, possibly on both edges, but definately on one edge.
     
  8. LP
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    LP Flying Boatman

    Paul, I think he is talking about frames(notches) to match the angle of the chine log as it wraps around the frames (as the planking does).

    For this, I would say yes, but I'm not sure of your construction technique and so that could turn it into a "maybe". And that's all provided I understood your question properly. Epoxy builds don't neccessarily require beveled frames (and/or chine notches). Sorry to be less than definative.
     
  9. Green horn
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    Green horn Junior Member

    Thank you thank you I knew something didn't look right when I set the chine log on top of the frames.. Just wasn't sure if I should notch it like that with a bevel.
    I'll post some pictures later today
     
  10. LP
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    LP Flying Boatman

    I just looked up your design on the web.

    The bevels for your chine log will need to be deep enough that the chine log does not stand proud of the sides of the frames. This is different that on the bottoms. On the bottom, you are removing part of the chine log to match the bottom of the frames. On the sides, you will be removing material from the sides of the frames to match the planking (and chine log). I hope that makes sense.
     
  11. rwatson
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    rwatson Senior Member

    Just looked it up myself - and now I understand.

    To illustrate your very correct statement, can i add

    "The vertical sides of the chine logs align with the frame sides."

    "The inner, upper corner of the chine logs should match the inner height of the notch"

    Simple diagram attached
     

    Attached Files:

  12. acp1934
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    acp1934 Junior Member

    It's also nice to bevel the tops of the chine to keep water from laying on them. The frame notch will have to match this of course.
     
  13. rwatson
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    rwatson Senior Member

    Thats a lot of work, much easier to fill it with some filling material to create a level or sloping top.

    Also, usually boats of this size are stored upside down, or on a trailer with a cover, so water in the chine logs isnt a real problem.
     
  14. LP
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    LP Flying Boatman

    Actually, this is a fairly massive boat. Anything that let's the water drain natually is worth considering. This would also be a very simple modification to the chine. Simple run the chine log through your table saw with the bevel of your choice selected. You can notch your frames to match or leave them square. If the notches are already square, you can fill the gap with thicknened epoxy and not give it a second thought.

    Good Luck on your built. It looks like a tough and seaworthy boat.
     

  15. frank smith
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    frank smith Senior Member

    I believe that the degree of flair is almost the same the for the whole length of the boat.
    It should be no problem to pick up the angle from the plans and bevel the chine log both top and bottom on a table saw, or with a skill saw using a guide.

    f
     
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