Lofting

Discussion in 'Boat Design' started by pamam, Aug 7, 2011.

  1. pamam
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    pamam Junior Member

    Hi,

    Does anyone know a good book to teach you lofting. I have the design for a 3.5 meter sail boat and need to do some lofting to be able to cut the plywood so that it fits on the frame.

    all help is appreciated.

    Mel
     
  2. peter radclyffe
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    peter radclyffe Senior Member

    Chappelle, Vaitses
     
  3. Tad
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    Tad Boat Designer

    Bob Steward's Boatbuilding Manual has good basic coverage of the subject, The Gougeon Brothers on Boat Construction has a good section on lofting, and Greg Rossel's Building Small Boats has an excellent lofting chapter......
     
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  4. pamam
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    pamam Junior Member

    Tado,

    Thanks for the great info,

    Mel
     
  5. rwatson
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    rwatson Senior Member

    Most lofting techniques teach you how to lay out the frames only.

    You mostly have to refer to the plans if you want to cut sheets of plywood to suit the hull shape.

    In the more standard plywood build, you simply mount the frames and any stringers, and then lay the ply on the frames, and measure approximately.

    Once the rough ply cutting is done, you screw and glue the ply to the frames, and then trime around the chines.

    The other alternative is to buy a cheap cad program like Delftship or Freeship, enter the frame offsets, and it will print you a 'skin' plan ( expanded sheets ) to use.
     
  6. pamam
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    pamam Junior Member

    Thanks, rwatson. I have AutoCadlt2011 but it does not seem to have such a function. I'll try the freeship and delftship s/w.
    Thanks Again

    Mel
     
  7. DCockey
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    DCockey Senior Member

    Ship and Aircraft Fairing and Development by S. S. Rabl covers surface expansion. No longer in print and used copies re not inexpensive. May be available via interlibrary loan.
     
  8. pamam
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    pamam Junior Member

    Thanks DCockey,

    For the book info, I'll check it out.

    Mel
     
  9. BATAAN
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    BATAAN Senior Member

    As a former shipwright, I learned lofting on my knees with some battens, flat pointed nails and a hammer and measuring tape, which worked for the traditional type things I was building. Howard Chapelle's BOATBUILDING was the book, and Sam Rabl's too. If you can find these, especially Rabl, it's easy.
    When employed at ILM I learned some different techniques that may apply to building full scale boats that need plywood components like bulkheads, frames, bunk flats and floor frames to be pre-cut, so I'm going to put that info on this thread.
    In movie models we used the program "Rhino" to loft and generated snap-together kits that we made with the laser cutter. This was necessary as a film miniature must be very exactly scaled down from the full size set or vessel being used, or it looks phony in the shot and you'll never make it work. First a very small scale test frame for the model was cut out of thin ply to see if it was right, which it usually wasn't, then adjusted in the computer, another small one cut and assembled to prove it, then the larger scale "bigature" was built. This gave a very fair and un-bumpy result with a bit of practice and we quickly got good at it, making many miniatures of various scales for three different pirate movies, a re-make of Peter Pan, War of the Worlds and others.
    Here you see a set being duplicated in miniature. The early small frame on the table with parts for the larger model being built. Also seen is an extension for an existing model, again totally computer lofted in Rhino and laser cut.
    And here are some full size sets, some of them the same as the models, again computer lofted and in this case steel frames that are plasma or water cut at the computer's direction.
    Hopefully you won't do to your boats what we often do to ours.
     

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  10. pamam
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    pamam Junior Member

    Bataan,

    Thanks for the info. I've found S.S.Rabl's book but they want $50.00 for it and I can't see inside of it to see if it is on my level, so I won't buy it. I have a few programs that I'm going to check out and this "Rhino" program sounds like it would be good if I can find it too. Wow, I'm just getting inundated with great info here, thanks a lot all of you.

    Mel
     
  11. BATAAN
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    BATAAN Senior Member

    Try to get a local library to order Rabl for you then photocopy what you need. It's a very well illustrated and simple introduction to lofting and since he was a professional aircraft loftsman which gets much more complex than boats, he understood it so well he makes it easy to learn.
     
  12. BATAAN
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    BATAAN Senior Member

    Rhino is a general purpose 3d design tool.
     
  13. pamam
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    pamam Junior Member

    Bataan,

    Thanks, I'll think about that. Our library is not even open all week due to shortness of funds these days so that will probably not help much, but I might reconsider buying it with this much good press.
    Thanks,

    Mel
     
  14. BATAAN
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    BATAAN Senior Member

    Best of luck. Also look on ABE books on-line, and maybe even Amazon. His Boatbuilding in your own Backyard is probably all you need. It was all I used.
     

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  15. BATAAN
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    BATAAN Senior Member

    The one I'm thinking of is "Boatbuilding in your own Backyard" by Sam Rabl. Going on Amazon I see his "Ship and Aircraft Fairing and Development" is available used at $50 and it's a deal at that if you are serious about lofting, but the boatbuilding book may be adequate for what you want to do.
     
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