Hi. I dont have experience with that shader. What I usually do in these instances is use a bright color in the Color channel to experiment. Start at zero for a height. Then raise it until you see something. Eventually the color should rise up on the object and you can find the right "height". This should be done on a dummy shader. Once you have that height to where you just see color at the very top of the object, copy the channel. Then paste it to the appropriate channel in your "real" shader. I know that is much harder than it sounds, but that is the only way I have found to get that effect. I have an image I did a couple of years ago here that has a shoreline foam. That is the technique I used on that. http://www.renderosity.com/mod/gallery/index.php?image_id=1098481 Of course this water has no height. It was just a flat plane. I actually placed the foam on the terrain object. But I believe you can use the same technique on the ocean object. I look forward to seeing your progress on it. If I get some time this weekend I will see if I can come up with something as well.