Boat building help

Discussion in 'Boatbuilding' started by lockley16, Oct 31, 2013.

  1. lockley16
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    lockley16 Junior Member

    The book doesn't say anything about building it, I have a couple other books that are pretty much build manuals but 1 is for like thirty footers and the other one is traditional building by steam bending and all that. None of them tell me how to use offsets.
     
  2. lockley16
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    lockley16 Junior Member

    Well two things, 1 I think I can do this because I have helped finish a basement from framing to Sheetrock (I know they don't compare but I am just saying I have taken on big projects and "won"). 2, I have a lot of tools but if I don't have what I need then I will buy what I don't have. 3, for drawing the frames, could I use finish nails in place of needles or something?
     
  3. SamSam
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    SamSam Senior Member

    Well, you might want to choose a simpler kind of construction for a first boat. It depends on how much you know and what tools you have.

    Using the table of offsets (TOF) is pretty easy, but I've looked around and can't find anything that easily explains it. I'll try to explain how to draw a frame using this drawing.

    [​IMG]

    Looking at the end view, there are two different halves shown. The left half is from the transom looking forward, the right side is from the bow looking aft.

    The vertical line dividing the two halves I'll call the 'vertical center line', or VCL. Above the drawing is a line labeled 'base'. I'll call it the baseline, or BL.

    Taking a 4x8' sheet of plywood and a framing square, go to the middle of an 8' side and draw a line down, using the square. That line will be the VCL and the top edge of the ply will be the BL.

    To make frame 4, measure to the right from the VCL along the BL and, using the square, draw vertical lines for the sheer (S) 18-2 (18-1/4"), for the upper (U) 17-4 (17-1/2") and for the lower (L) 12-6 (12-3/4").

    Measure down from the BL 6-4 (6-1/2") at the S line and make a mark. (+) That is the S point. Do the same at the U mark, measuring down from the BL 13-5 (13-5/8"). That's the U point. The L point will be at 18-6 (18-3/4").

    Measure down the VCL and put a mark at 20-5 (20-5/8"). That will be the keel point.

    Using your straight edge and a pencil, draw lines to connect those four marks and you should have one half of a full size #4 frame. Repeat all those steps on the left side of the VCL and that will be the whole frame, full size. Page two of the drawings tells how wide the frames are ( I can't read any of the plans, they get too fuzzy) Maybe it's 4 "..? Anyway draw lines x" in, parallel to the outside lines, round the corners and that's the frame.

    If you understand that, I'll tell you how the offsets work with the side and top views of the boat.

    I'm just using the plywood as an example, when you make the boat, you'll draw the frames full size on paper and then transfer them to the plywood, that way you can nest the frames to use the plywood efficiently.

    Butcher paper is good to use as it is waxed and less likely to expand or shrink with humidity. You don't cut the paper patterns to size and trace on the ply, but tack the whole page on the ply, poke a sharp needle or something through the corner points (+) on the pattern into the wood, remove the pattern, then connect the points with a straight edge and pencil, then cut the frame.
     
  4. SamSam
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    SamSam Senior Member

    Somehow two half explanations got posted, so I deleted them.

    Sure, a finish nail will work. All you're doing is transferring the points on the pattern to the wood. A compass point is ideal.

    When you're making stuff like this, the more careful and accurate you are from the start, the better off you'll be all the way through to the end.
     
  5. lockley16
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    lockley16 Junior Member

    Ok, I was wondering what was up with the two posts. I think I have already figured out how to do the frames. I will post a pic and an explanation of what I have been doing. Keep in mind that the drawing are 5.6 times smaller than the actual. It might be around 3ish (EST) when I post the pics.
     
  6. lockley16
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    lockley16 Junior Member

    Sorry for being longer than I said. I was doing something and I didn't realize it would take that long. Here are 4 of the 8 mold/frames. The way I have drawn them is by taking the largest number for the height and subtracting the smallest number in height by it. That is probably the wrong way of doing it, but again it has worked for me so far.
     

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  7. SamSam
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    SamSam Senior Member

    Well, if you notice on page 2, the top of the frame is slanted so water runs off, if you cut the frames straight across as you show, you'll eliminate that.

    I'm not sure if you understand or not how the horizontal breadth measurements and the vertical height measurements work together to locate points on the frames that give it it's shape. I guess you must as what you drew seems to be the shape. But if you're just taking a ruler and measuring the drawing and then doubling or 5.6 times-ing the measurements, that won't work, you have to use the table of offsets to be accurate enough.

    The baseline is just an imaginary reference line that all the height measurements come from. Most plans have it an x number of inches below the boat so the numbers would be opposite than what your plans are, the keel would be closest and the sheer farthest away. Some use the waterline as the baseline, so the keel would be a negative number and the sheer a positive one. I can see how it can work doing it like you did for the frames, subtracting the smaller from the bigger, but I don't see much reason for it.

    When it comes time to attach the frames to the strong back, you will definitely need a baseline, as the measurements from it to the keel will determine the shape of the bottom. If you don't use a baseline to position your frames correctly, they won't work, so it's best if you make sure you understand how to use the offset table.
     
  8. lockley16
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    lockley16 Junior Member

    Well, 1 the top, well... there is not top, it is all open. It is all open like an optimist. Also I just kinda threw these together to get a general idea of what it will look like. 2, I will try to find stuff that shows me how to use the offsets correctly.
     
  9. hoytedow
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    hoytedow Wood Butcher

    Try to imagine the offsets top view and side view in 3 dimensions so that you can attach them in your mind. I wish I knew an easier way to say it. If your school has a drafting teacher he might have a 3d drafting program he could show you.
     
  10. lockley16
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    lockley16 Junior Member

    Well... I am homeschool but next semester I am taking an engineering course. I am not sure if we will be using cad or something like that, but I would expect something along those lines.
     
  11. lockley16
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    lockley16 Junior Member

    I was again going back through by book and I remembered that the guy was able to keep the boat at 40 pounds. I wasn't sure how until I looked at a picture of him holding it. There are no ribs in the boat.
     
  12. hoytedow
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    hoytedow Wood Butcher

    The frames are just the shape to build the boat around. The boat is then lifted off after the glue has set.
     

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  13. hoytedow
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    hoytedow Wood Butcher

  14. hoytedow
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    hoytedow Wood Butcher

    A hint. if you put some saran wrap onto the building jig,between the jig and the hull, the glue won't stick to it.
     

  15. lockley16
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    lockley16 Junior Member

    Ok I think I got it now. I will try to make a scale model of the mold with balsa wood to see how it will turn out. I was looking at the pics, all they do is temporarily screw it in. And then what? Do you fill the holes with wood putty? Again, I am soooooo sorry for asking so many questions, I just like to get everything in order before I do something because I have a bad rep of not finishing projects that I don't know how to do.
     
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