Hi David, so I untrimmed the outer boundary of your hull, and then retrimmed with the cutting curve you have in the file there. Note that this also removed some trims from the sides and I don't seem to have the cutting curves for those ones in the file you sent.

But when I do the trim over here, those areas seem to behave fine:




What is the exact process that you are doing when you are trimming the hull?

Are you doing something like projecting the curves on to the surface as an extra step before doing the trim? If so, then avoid doing that - instead just use your planar curve directly inside the Trim command as the cutting object, and let the projection mechanism built directly into the Trim command handle the projecting.

It actually makes things a lot more difficult for MoI when you project things on to a curved surface as an extra step before the Trim, because it actually makes the Trim command do a bunch of extra work to re-pull the 3D curves down to the UV space of the surface again.

Anyway, if you let me now what steps you are doing to trim the hull, and possibly if you can send me the surface and cutting curve _before_ doing the Trim so that I can repeat your steps over here, that may let me help you further.

- Michael