I begin with the premise that the inward shift(s) that catalyzed Vincent Van Gogh's spiritual quest is best represented by his interest in the Sea imagery (perhaps as an archetype?), which also involves boats and fishermen. This shift is a movement towards self-liberation and creativity, towards the integration of his many interests (Bible, nature, novels of his day, Japanese art). If we use the Sea imagery as a clue to his calling towards creativity, then a numerical breakdown of Vincent's boat paintings in specific geographical locations in his life makes sense.  

The changes that occurred in Vincent in the Arles are evident in a numerical table of thematic motifs provided by Tsukasa Kodera in Vincent Van Gogh: Christianity Versus Nature. Out of fifty-five paintings with a boat imagery, eight were painted in 1882, four were painted in 1883, one was painted in 1885, as well as 1886, ten were painted in 1887, and a couple were painted in 1890, but a whopping twenty-nine were painted in 1888.  To our knowledge, 1888 is the very year that Vincent lived in Arles.  In March, he began painting the blossoming orchards, much like those in Japan.  In June, he briefly visited Saintes-Maries-de-la-Mer to sketch boats and the sea.