Laboratory study of a stationary oblique plunging breaker for surfboard testing

Consider a water wave which is obliquely incident on a sloping beach. An observer looking along the wave front from the beach sees the portion of the wave closest to him to be already broken while that far from him is still in deep water and unbroken. In the transition region, the waveface reaches its maximum slope and this is therefore the part most suitable for the surfboard rider, who uses the waveface much like a skier uses a mountain. Because the wave breaks when the water depth reaches a particular value, the path of the break point, and therefore of the surfboard rider, is along the sea bottom contour. His average velocity is that of the intersection of the bottom contour and the wave. He therefore moves faster than the propagation speed of the wave even if his velocity is constant.