My contribution here attached : the formulations used for the hull geometry within the new "Gene-Hull Sailboat 3.0" application that I have just posted.
The approach is based on fit for purpose analytical functions defined directly in the usual cartesian coordinates x,y,z (not B-splines or Nurbs, neither elementary polynomes) , with adimensional parameters dedicated for each purpose, in order to cover the widest possible variety of hull shapes for a sailboat. That allows to directly draw the traditional 3 views 2D with its waterlines and its buttock lines, an isometric perspective, and to compute the hull contribution to the usual ouput about hydrostatics, loading influence, stability, righting moment, ....an approach that can match with a standard spreadsheet like Open Office Calc.
The needed input includes exactly (for the hull shaping alone) :
13 geometrical data in metric
2 geometrical data in %
1 angle (for the so-called alfa transformation)
21 adimensional parameters
, so in total : 37 input data
From a given set of input data, we can either :
- change only the geometrical data in metric : you build another project with a similar shape for the hull
- change only the adimensional parameters : you build another hull shape within the same geometrical constraints.
- change all the data, then for a new project with a new shape of hull
I pay attention to use combination of functions which keep a smooth evolution of the curvatures, which does not generate curvature max or min other than the ones necessary to shape the hull and to comply with the input geometrical constraints. It is a concern about the so-called « fairing » issue.
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