You should probably get rid of the dithering altogether as it's not doing anything for your piece. If you're going to apply dithering, you need to use it to fill an aesthetic or technical goal.
Your water is way too dark. My monitor is probably badly adjusted, as I often have trouble making out darker colors, but I personally feel it's too dark regardless. I looked at this before and thought the entire bottom-half of the picture was black. I actually assumed the light part was the water, and I just thought to myself "Okay... Weird." Now I see the 'water' down there.
I don't really think adding waves made it any better, to be honest. If you still want to add them, I might suggest adding a highlight, as waves are very reflective, and can portray a wide range of values, I don't think you can get that effect with just 1 or 2 colors, not 2 dark shades, anyway.
