I have come across a model that demonstrates a problem when running nonmanifoldmerge. All of the initial objects appear to be valid. If I run nonmanifoldmerge on the boat hull and the green plane it succeeds. I can then run the area command and compute the area of the merged object. If instead I run nonmanifoldmerge on the boat hull and the red plane it appears to succeed. However, it cannot calculate the area, and if I explode the surfaces it appears to fail on a region at the bow. Interestingly, I can create a plane a 1/4" forward of the red plane and all works fine. This behavior seems repeatable in Rhino 7 and 8. I’ll send the model separately. Any thoughts would be appreciated.
Kind regards, Larry