Are those green lines curves used to control the boundary blend? If so, you can see the ripple follows the curve. If so, get rid of the extra curves. The only curves I used are highlighted in red in my pic. too many curves cause the ripples, you only need 3 total for each quilt. Left, top, and right used for the top quilt, and I made sure the boundary edge conditions were normal to the top datum plane. For the bottom surf, similar, but I used the edges of the top surf instead of the L and R curves, and used curvature continuous (to the top quilt) for the edge conditions, then I merged it.