Taking of lines

Discussion in 'Boat Design' started by Woobs, Aug 5, 2015.

  1. Woobs
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    Woobs Junior Member

    My apologies if this thread is in the wrong category...

    I have a 1972 Greavette Sunflash IV boat. The manufacturer closed in 1978 and the Marine Architect that designed her has passed away. There are no known records or documents available (after a decade of searching).

    I would like to reproduce the line drawings of this 18' boat. I have heard of ACBS chapters taking lines of certain boats so, I know it can be done. Is there a step by step guide to this process (for dummies) somewhere? A book, paper, PDF, instruction manual?

    I don't have any design software so this would be strictly a pencil and drafts table "old school" effort. Is there a reasonably priced software package that i can use?

    Thanks for any and all help :)
     
  2. gonzo
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    gonzo Senior Member

    You don't need any software. A few strings/straightedges, measuring tape, pencil and paper are enough. Start by creating a grid with either strings or straightedges and take measurements from them to the hull. Since it is a hard chine boat, the most important and easier measurements are to the edges of the chines, keel/bowstem, transom and sheer. Transcribe those measurements to paper and fair the lines.
     
  3. DCockey
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    DCockey Senior Member

  4. TANSL
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    TANSL Senior Member

    Woobs, although obtain good data is not as easy as Gonzo seems to suggest, it is true that his method is typically used worldwide to obtain data from an existing boat. They can be obtained by laser meters, etc. but I guess that does not interest you.
    If you get some data on the ship, I can, with my software and your data try to get a CAD body lines drawing of your boat.
    This greatly simplifies subsequent calculations you need to perform.
     
  5. Woobs
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    Woobs Junior Member

    Thanks DC... I downloaded that!

    TANSL, short of pointing at a PowerPoint presentation on the wall, I have no idea how to use a laser. I'm not against them (or not interested)... just ignorant :). Thank-you very much for your offer! I would like to have as accurate, and professional drawings as I can get.

    I have also contacted the person in charge of taking lines at my local ACBS chapter (having been a member for 10 years) and they pretty much blew me off. I can only assume it's because my boat isn't a 100 year old, $ 250,000 boathouse queen that sees the light of day once a year at boat show time.

    I can't express how great it is to have found this forum and these people whom are both knowledgeable and willing to help. Thank-You.
     
  6. Woobs
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    Woobs Junior Member

    WOW, DC that's some manual... I think I need to be a NA to get that much detail to register in my brain. :)
     
  7. SamSam
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    SamSam Senior Member

    If you scroll down to the bottom of the page you'll find "Similar Threads" which may help.
     
  8. Ike
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    Ike Senior Member

    All you really need to do this is some non stretching string, a plumb bob, a good measuring tape, some chalk and duct or masking tape, a pencil or pen and some paper. Also you need a flat surface (hopefully level) to put the boat on, and if you are really lucky a blank wall, but you can do it without the wall, it just makes it easier.
     
  9. Woobs
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    Woobs Junior Member

    Okay, I understand the wall as a solid reference point (as is the flat/level floor). Center line down the top view and the, bow view and/or stern view but, what of the side view? Where do you make your centerline there? The waterline, shear or the floor? What grid size to adequately show the fairing if the hull? Which (and how many) points of reference?
     
  10. Ike
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    Ike Senior Member

    You make your measurements in three views. Up from a baseline (the floor). The side(portrait), from the wall, and length wise from a line drawn on the floor. The line on the floor can be arbitrary, or you can drop a plumb bob from the bow or stern and where it strikes the floor becomes the line you measure from. Oh yeah I forgot one thing, you need a really big carpenters square to make sure these lines are at 90 degrees to each other and that the centerline o the boat is parallel to the wall. You can make one with three pieces of straight (they have to be dead straight) wood to construct a 45 deg triangle.
     
  11. viking north
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    viking north VINLAND

    Go to my posts on this forum (under Boatbuilding scroll down and select The Nancy G ----posts 11 to 15) you will find a basic fool proof detailed guide with photos. ---
     
  12. Woobs
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    Woobs Junior Member

    Brilliant!!!!!! Thank you. Now this all makes some sense.

    I imagine it is somewhat more difficult with the boat upright as the big square cannot simply lay against the straightedge and a ladder and the plumb line falls from hull to ruler not, vice versa.
     
  13. claydog
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    claydog Junior Member

    Well done.
     
  14. claydog
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    claydog Junior Member



    Using the same principles’ as Viking Norths method you can do the same thing with the hull upright if you have a grid (think tile squares) on your work surface floor and a 2 axis self-leveling lazer level. The trick is lining up the keel center line with the grid on the floor and leveling the hull. Line up the vertical axis of the lazer to a grid line on the floor then use a plum bob to transfer reference points to the grid in plan view, measure the length of the plum bob to get height above grid for a side view.
     

  15. viking north
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    viking north VINLAND

    I think I mentioned on one of the posts the procedure with the hull upright would simply be to level up the boats keel and operate the plumb bob in reverse. I.E. from the station point marked on the hull let the plumb bob dangle down to a point on the big square. However if at all possible invert your hull, let gravity make it easier to achieve accuracy. Especially so on smaller hulls. In my case I inverted the hull for other reasons so took advantage of it's orientation in taking off the lines. Being old old school I'm intrigued by Claydog's system which i fully grasp but am reluctant to venture into :D

    A yacht is not defined by the vessel but by the care and love of her owner---
     
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