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Curves and polynomial of 3rd degree

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Brings back fond memories of studying and tutoring algebra, but it's not something you need to know about in terms of ship modeling.


The "modeling" the narrator is speaking about is Mathematical Modeling, not physical construction of hulls.


These days, I think the only time polynomial mathematics come in to play is all "under the hood" when using CAD and illustration software. The computers use the math, not the CAD operators or the architects. Important stuff, but mostly when developing the computer software. Of course, not really being into CAD myself, maybe someone with more experience on the subject can chime in on that.


But, if you enjoy the math, study it. It can be fascinating stuff and great mental exercise.



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The key for us is the use of the word "spline", and the picture of the draftsman using a batten to find or draw the lines. In CAD most programs can draw a curved line along a series of points that don't fall along a straight line.  You could use this to draw an osilating line as in the video. This does all that math for you.


In DesignCAD they are drawn using the "Draw Lines Curved" command. In AutoCAD "Draw Spline". DesignCAD also has a curve, called a "Bezier curve, but that involves tangents, and I have never used it.


This is the type of line I use to trace a sheer, or a frame line. In DesignCAD you can even specify a file with a list of points along the curve, and it will draw the curved line for you. If you have an offset table, these points can  be generated from the table. The kicker is that the points in the file must start at one end, and finish at the other. This means determining the flow of the points in the offset table. I generally use a spreadsheet, to manipulate the offset points, into an end to end flow.

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Have never used the Spine command in General Cad, I do use the Bezier. If I am working with spiral transition curves, I do the line work in Traverse PC. That way I can use the defined data for the Spirals in and out along with the connecting circular curve to match the record. The Spine command does look like the one to use with offsets on a hull, thinking that using Traverse PC to obtain the XYZ coordinates from offsets, then taking that into Cad, might be a good match. Been looking for some plans to try that combination on.


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