Overlapping

To create a sense of distance, It is helpful to paint "forward".  Start with the underwash ( in this case the sky and the water), move closer with a suggestion of other boats in the harbor (it is not necessary or even desirable to sharply define these objects), and then get the darks and warms going in the two foreground boats.  Their masts overlap the other boats and the far shoreline. That's why it's best to leave the distance undetailed; details and texture out there would confuse the viewer after the foreground details are added.  The building on the left is also kept in silhouette and very simple, but a bit darker and overlapping in such a way as to come forward, as well as stop the eye from going off the page.

It might help to see a photo of the scene to see how much simplification I employed to keep the attention in the foreground.