Surface w/polylines: y direction point in middle, x direction variable

Hello everyone,

I would like to create a point in the middle of the two longitudinal lines as in the picture.
This point must be variable on the X axis.

It didn’t look that hard to me, but the fact that the surface is build up from polylines makes me not understand how to do this in a clean way.

Is there anyone who can help me with this?

Thanks in advance. (11.2 KB)


Many ways… (15.8 KB)

You could add Surface/Brep Closest Point to this.