Probably the most striking aspect of this painting is the backlighting which gives the calm sea a special sparkle. Along the starboard side (right side) of the schooner, the hull is reflecting light along it, contrasting with the deep shade of the stern.
Having the stern in deep shade, really accentuates the highlighted reflection on the water seen past the schooner on port side (left)
In both illustrations, note the importance of considering how the light is striking the lightly rippled water. The smoother water in the wake of the schooner is light, reflecting the backlighting, but not highlighted like the parts of the wavelets that act like little mirrors. Backlighting gives more contrast in the parts of the wave, with the part sloped toward you that allows you to look into the wave being much darker. Also, note that the wavelets between you and the schooner alternately reflect the dark colour of the stern and the canvas of the large sail. Getting the reflections right on water is critical to the mood of a marine painting. And backlighting gives great effects to work with in creating this mood.