On the Coast of Holland, 42 x 34 inches
Ships' masts provide vertical elements to counter the horizontality of the sea. The vertical element provided by the fisherman is extended by his reflection in the wet sand, and provides a visual link from the bottom of the painting through the boat to the top of the composition. I've noticed that old master seascape painters often make an opening, or lighter area, in the clouds behind the top of a mast. The light tone contrasts with the dark tone of the mast, creating a focus of interest for the viewer's eye - a kind of full stop at the end of the sentence - and also can suggest an extension of the visual path into the infinite.
The intervals between sets of elements should be varied, to create more visual interest. Avoid painting regular spacings (like the posts in a fence) or the scene will appear unnatural. This rule could be broken if the intention is to create a surreal effect.