Wonderful artwork! Top notch
Unfortunately, sails couldn't be painted like this, though. Or rather, they could -- but because the sail is constantly furled and unfurled, the paint would flake and chip off very quickly, and with rather a distinct horizontal bias. The paint would not smudge, smear, or run... simply flake right off the canvas.
We might consider an exceptionally good attempt at emulating this effect, but generally speaking, "painted sails" are strongly discouraged.