When we will show a smooth bending on a ship we do it with a light an dark in same colour divided by an one pix line. But that line isn't really showing a smooth bending! If we extend the new shading with the colours in different nuances on each side of the bending, and then fill the inbetween line for line each time slightly darker (or lighter, depends on the way the bend goes) nuance, it will more proper show the bending
I've added an example, where a comparison is viewed.