Lines plan from measurements

Discussion in 'Boat Design' started by Rom, Nov 2, 2020.

  1. Rom
    Joined: Oct 2020
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    Rom Junior Member

    Actually ... I've only just thought about it ... a bit of a fiddle but plumb line from the widest part of the hull down onto the ground -> Perpendicular line drawn here going fwd and aft. Then at each station, a vertical reference ( a straight stick if you like ) then measure in towards the hull using laser or other tool. Will have to find the center line on the bow and stern then measure out to get that perpendicular line. See badly drawn sketch:

    upload_2021-2-10_18-2-52.png
     
  2. gonzo
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    gonzo Senior Member

    It is relatively easy. A laser measuring tool is quite cheap and accurate. They make them with a built-in level, so you can be sure the measurements are vertical. The target reflectors make it easy to use, even in sunlight. You will have to loft or somewhat fair the lines after you take them. It doesn't matter if the boat is level fore and aft. Athwartships it helps because you can take measurements at both sides and average them without doing a lot of trigonometry.
     
  3. TANSL
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    TANSL Senior Member

    Don't pretend to take points for waterlines, that is difficult and impractical. Take the points from each frame where it suits you best. Forget the water lines, you will create them during the fairing process.
    Take measurements only on one side, do not complicate life.
     
    Last edited: Feb 11, 2021
  4. fallguy
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    fallguy Senior Member

    I am too tired to reply, but basically, you run a reference line and pick points along it. Get a quality laser that shoots a reference and side lines and the laser will find squares and you tape the hull and find all the vertical distances from a baseline and move the laser to each one and then take a length measurement to the lasers point reference.

    A couple hours with beers.
     
  5. Rom
    Joined: Oct 2020
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    Rom Junior Member

    Thanks yes I believe we are all talking about the same thing. Once the reference is established it should be fairly straight forward. Agreed with the water lines, they don't have to be perpendicular to the base line. The Software will probably create new ones that are ... I'm just building a reference for the sections.

    I'll use a laser with a level, go vertically down at the widest part of the vessel then perpendicular using the center line extended from the bow as another measurement point.
     
  6. fallguy
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    fallguy Senior Member

    A good laser will allow you to square off it and measure to it and then you can raise it and lower it from sheer to baseline.

    D4EE18E7-FA78-49CE-A0DB-6859F7DA5B42.png
     
  7. gonzo
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    gonzo Senior Member

    My laser can calculate vertical heights from the horizontal distance and the distance to the top point. It does all the necessary trigonometry. It also has a built-in level so there is no guessing about taking a vertical measurement.
     
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  8. Heimfried
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    Heimfried Senior Member

    Yes - but will it help?
    To do this, you have to mark a point at the hull and another at the ground the former exactly vertical above the latter. When you did this, why not hold a tape at these points and simply read the distance?

    Edit: (Additionally there are some other points to observe (and things to do) in order to get a reliable measurement.)
     
    Last edited: Feb 11, 2021
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  9. TANSL
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    TANSL Senior Member

    With that laser, can the trick of the archaeologists also be used?
     
  10. gonzo
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    gonzo Senior Member

    The advantage of a laser with level is that it can take measurements from a know point and measure distance and angle from the vertical simultaneously. Making vertical measurements is also easier if he want a point vertical above a known point. There is no need to make any marks on the hull.
     
  11. TANSL
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    TANSL Senior Member

  12. fallguy
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    fallguy Senior Member

    That is really cool. What brand n model?
     
  13. fallguy
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    fallguy Senior Member

    A vertical mark on the hull would help define the height off the sheer and/or baseline to measure back to the laser from. Just a temporary mark on a tape.
     
  14. TANSL
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    TANSL Senior Member

    If you are using a laser you don't need any vertical line drawn on the hull. Nor if you are not using a laser.
    You need of course to materialize the base line but nobody seems to need it???
     

  15. DCockey
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    DCockey Senior Member

    gonzo, what is the make and model of you laser unit? Is it a "total station" which are used by land surveyors or less expensive?
     
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