I've only been using Inventor for a few days and am having a problem using 3D polylines and Splines from Autocad i.e. they are already drawn in 3D space. When I bring the dwg into Inventor they lose all of their Z information and appear in the sketch viewport as flat lines, which is not much use. They are the loft lines of a ship and are set out at exact locations along the keel. I'd like to know if they can be used inside Inventor without having to redraw them, which would be a real pain. I know if I lay them flat in AutoCAD they come into Inventor without any issues, but I lose their keel setout. Any suggestions welcome and please understand that I'm a complete beginner with Inventor, so don't get too technical. Thanks in advance.