Hi David,

> I´ve searching the retrimmed hull, but there are the same problem.
> When I make a shell, there are rare parts. :(

It looks like probably a bug in Shell, it is likely having difficulty with the difference in scale between areas within your same surface. Those little fillet curves are much smaller in scale than the full surface.

You may get some better results if you build it in some sections instead of as one large surface, so that you don't have a large change in scale between the trim curves and the surface, or maybe a more reliable method would be to do the shelling first on the initial lofted surface, and then boolean away holes in that solid, rather than trying to use Shell to create a solid from a complex set of trims like this.

That's what I've done in the attached model version - I untrimmed everything and then did Shell on the plain surface to make it into a solid.

Now you can cut that solid with your curve with boolean difference:



That will cut the solid up into 2 solids, and you can select the top half and delete it.



That seems to produce a good result in these little problem areas:




Booleans are a much stronger area in MoI than shelling is, so it is better to use Shell in more simple situations when possible, and then use Booleans to do more work, instead of making Shell do more work...

- Michael