It works as it is. It's a lovely "portrait" of water, wind and sky. If you add a boat you change the focal point and the meaning, unless it's tiny on the horizon. Why would you want to do that? My observation is that most times when folks paint a seascape (or skyscape over the sea) they have one focal point of difference from the rhythmic pattern of the waves. Your sky provides some of that. If I were to change anything I would provide that in a different wave break toward the right side foreground, rather than any kind of boat. But it doesn't need any changing to be effective. It is as it is.
