In August 1971, a group of activists invited Roger Raveel to take part in their action against plans to drain the old Leie arms between Machelen and Deinze after a large stretch of the Leie was canalised. On a raft covered with blue plastic bags, Raveel placed a painting and had the whole thing sail down the Leie to Afsnee amid great public and media interest. This changed the plans and preserved the original Leie. Raveel records this event in the painting A ship passes by. On the occasion of the event, Raveel also creates several graphic works, including a poster.