Please see attached 3dm and grasshopper file.
The 3dm file contains a surface which represents the bottom of a boat hull. In grasshopper, I have created a rectangle in the XY plane. I then projected the 4 corners of the rectangle upwards in the z-direction and found the projection of those 4 corners on the bottom of the hull surface. I next wanted to find the normal vectors to the surface at each one of those points. I used Evaluate Surface to do this. However, the vectors returned are clearly not normal to the surface. This is not just a matter of the normals being flipped. The normals are pointing in what are clearly the wrong directions. I am wondering if the issues is in the surface itself, but I cannot figure out the issue. See attached screenshot.
Thanks in advance for any help!
Hull_Shape.3dm (156.2 KB)
Position Keel Cooler Project.gh (12.6 KB)