Delftship Tutorial: How to find the sail's Center of Effort and sail's areas

Discussion in 'Software' started by quequen, Oct 28, 2011.

  1. quequen
    Joined: Jul 2009
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    Location: argentina

    quequen Senior Member

    Hi. I used to use AutoCAD to find sails center of effort and sails areas, but now I find Delftship / Freeship can do it faster. Is pretty simple:
    1- Copy the .fbm file with a new name.
    2- Open the layer box and turn off Hydrostatics, symetry, intersections, for all layers. Also, put all thikness and densities on cero.
    3- Create new layers, one for each sail (main, jib1, jib2). Change working layer to one of them.
    4- At the Profile view, if you have a reference image of your sails, load it and correctly scale and position the image.
    5- At the Profile view, use the Tools - Add Box command to insert a new box, setting "x,y,z" coordinates of opposite corners (leave "y" coordinate at 0, so your box will have not thikness). Subdivide the sides of the box to obtain as many vertices as needed for drawing sail's border, and turn some vertices to "corner". Then drag the points of the plain box, following sail's border. Repeat for each sail.
    6- Go to the layer box and put Density of the sails layers to 1, also put Thikness of the sails layers to 0.01. All sail's layers must have the same density and thikness.
    7- At the layer box turn on "hydrostatics" just for the sails layers. Keep symetry off.
    8- Run an "Hydrostatics Report". At layer info you have the sails areas, and at CG info you also have the position of velic centers for each sail, and at the bottom, the position of the overall Sails Center of Effort. Remember that LCG equals "x" coordinate, VCG equals "z" and TCG equals "y" coordinate (and must be 0, offcourse).
    9- Finally, in "wireframe" mode, turn on the control net and use Edit-Point-Add to create points for each sail's center and for the overall sails center of effort. That's all.
    Large to explain, but easy to do, trust me...:D
  2. lewisboats
    Joined: Oct 2002
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    lewisboats Obsessed Member

    I have used something similar although less complicated. It did not however give the overall CE so thanks for the effort to figure this out.
  3. Kudzu
    Joined: Jan 2008
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    Kudzu Junior Member

    This I have to try!

    I have been playing with sails and this sounds great.
  4. quequen
    Joined: Jul 2009
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    Location: argentina

    quequen Senior Member

    Lewis, you're welcome!. Will you share your own metod? may be we can make it better!

  5. LP
    Joined: Jul 2005
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    LP Flying Boatman


    More simply, draw your sail(s) on a single layer or on independent layers. Turn "off" hydro and symmetry, as you say. In the surface properties box at the bottom of the layer properties window will be your sail area(s) and x, y, and z coordinates based on your zero datums.
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