If it is the improvement of the painting as fine art you are asking about, you are right to feel it needs something. The image lacks a center of interest. The center of interest is usually the area where the viewer's eye tends to look naturally, or is drawn to by the composition. The center of interest is very often the most detailed or focused area of a painting, and is also where you will find the lightest lights and darkest darks, as well as the greatest contrasts.
However, placing your center of interest does not mean centering it. There is a rule of thirds that says the better compositions tend to have the center of interest placed at the cross points of a grid of nine like this:
Here is a discussion of composiiton in photography where the image came from; the same rules apply in painting:
http://blog.syracuse.com/photographe...mposition.html
One more suggestion for your next painting (unless you are willing to do some creative cropping of this one) is to avoid placing the horizon line in the center of the paper. It tends to divide the paper into two halves which can easily become dis-unified. An off-center horizon tends to lead the eye and placing an object to focus on becomes much easier. And always make sure your horizon is level on a painting of the ocean . . . unless you are depicting a rough sea and a nearly capsizing boat!
By the way, you have done an excellent job of painting the water's edge and the sand . . . and, except that I know it would not be simple task, I would expand the area of sand and take the actual ocean down to a smaller fraction of the canvas.
Here are a couple of illustrations of what I am talking about (pardon my poor computer painting skills, but I think you will get the idea):