Hi Manu, yes I'd agree with kevjon above - try using the option for "Loft Style: Loose" which will be in the upper right command options area when you run the Loft command.

It will make a more relaxed surface that is just generally guided by the inside curves rather than forced to go through every single curve. When the loft is overly constrained by trying to be forced through every single curve that are close to each other it can easily lead to bumps and ripples in the surface.

- Michael

Hello Manu,

maybe You can make it also with a blend (red)- a big surface with a simple network (blue curves) and a helper surface (green) to control the curvature and direction of the blend!?

Kind regards
Karsten