Very thank you Michael and ycarry.

Definitively I had two problems. A bad managing of the export options....and I am a dreadful modeler!

The thing is that the hull was any rare parts in the areas that Michael searched yesterday. I uploaded only the main part of the hull, but I had filleted another surface and I damaged the hull.

I show one of the conflictives areas when the mesh is built.(first image)

ycarry: when I export with your settings, I get too much polys, do you? (second image). Anyway your good advice (for MoI and for Blender) have been very useful for me.

Thank you again! ;-)