I won't be doing it, but maybe someone here is really ambitious and we can live vicariously through you.  You would take your canvas/dropcloth/sheet backdrop and make it twice as long as you needed.  The ends would go around round poles.  Some type of gear or manned hand crank at the top would turn the round pole, which in turn would move the backdrop.  Like a fan belt.  Suddenly the ocean is moving and the ship is sailing.  It just looked really cool.