Notes about the colours
After returning home to Arles, Van Gogh made three more paintings from the drawings he had done in Les Saintes-Maries-de-la-Mer. In the drawing of Fishing boats on the beach, he had even made notes about what colour to use for each part of the painting.
I did the drawing of the boats as I was leaving, very early in the morning... It was before the boats cleared off; I’d watched it all the other mornings, but as they leave very early, hadn’t had time to do it.
Letter to Theo van Gogh. Arles, on or about Tuesday, 5 June 1888.
Look for the notes on colour on the drawing of the fishing boats and compare with the painting Van Gogh made after the drawing.
Compare the drawing that Van Gogh made 'at the spot', with the painting that he made back home in his studio.
Take a look at the painting and investigate whether it deviates from the drawing.