Attached Link: http://larashots.com/appleyard/temp/renderosity/suw_01i_lightmat.jpg

"*But the sea level on the dock wall and the side of the dredger is flat level without wave humps.*" :: On a closer look I can see 2 water levels :: a wavy edge caused by waves, OK; and a horizontal line caused in the light material as at the attached link, by treating the water level as constant 0.0000 . It seems that I must replace that 0.0000 water level by some maths to calculate the water level at that point from the displacement value at the water surface point above point P.

Please where is information about the procedural waves that you mention?