Geometry Module - Creating faces from wires

Hello!

I am design a ship propeller using Geometry Module. I created a closed wire representing the blade contour shape. After that I tried to create a face using the refered wire. But the created face presents a surface too proeminent on the center region (like a mountain) :

image

I would like do create a smooth surface

Please, someone could show me how to do this?

Thank you!

Marco