Framed print of fishing boats by Vincent Van Gogh

a small framed print of “Fishing boats on the beach of Les Saintes-Maries-de-la-Mer” by Vincent van Gogh (1853 - 1890), Arles, June 1888.
Any idea why these fishing boats seem a bit unreal? Compared to the uneven sandy beach, they are actually too two-dimensional. They consist of flat areas of color, which are filled in within solid contour lines. The boats don't cast shadows on the sand either. Van Gogh thus applied elements that he knew from his collection of Japanese prints.
Van Gogh would have preferred to have painted these boats on the beach on the spot. But that didn't work because the fishermen carried out very early every day. He did draw them there, after which he made this painting at home.

in good vintage condition with some small traces of use at the frame. See pictures for details.