Hello
To export from Delftship, go to:
File > Export > DXF 3D Mesh (I think)
It used to be possible with Sketchup 6 to import it, but it seems in 7 it isn't.
However, in SU6 you would go to:
File > Import > From the drop down select "Import as DXF 3D Mesh".
Then it will be imported.
Hope this helps!
Mike
PS: I think this is probably the wrong board, but I'm sure a mod will move it.