I posted a wake for a submarine some time back on this topic. What I did was create a wedge shaped flat terrain and put it just below the water so you could see it through the water. Use a turbulent material like a cloud or something that works with the particular water you use. Experiment. Make the water transparent enough to show it. You could take this a step further by booleaing an upside down terrain behind the boat with the water plane. Texture it with your water only more white, like foam. Then put your ridges in with a regular terrain on the water plane level, find a foam texture. Hope this helps.