Panman,

I did a little experiment with wire ribbing and different materials for body material. The ribbing becomes considerably more pronounced under water. I don't think it has so much to do with the ribbing as much as the change in color once the body becomes wet and darkens, thereby making the ribbing more pronounced. Tie one up and put it in water and you should be able to tell if the copper will shine through the body material.

Hope this helps