If you have a sun and clouds, they will have shadows in the atmosphere/haze. I don't think you can turn that off totally, and if you disable secondary (in the cloud) there will be no internal shadows in the clouds either. Reducing haze would be the best bet, I guess. But what I see are mostly reflected clouds in the water. If you make the water completely without waves you loose the vertical stripes. You might want that only in the distance where striping is strongest (distance shader). Hope this helps a bit.
Or you could use a reflective shader and only a transparent water shader with some waves for the front (using a distance shader again).
