While I thrash out the fine points of motion blur and caustics, I add volumetrics into the pot. I got the searchlight to work...after a fashion. It won't show up if pointed away from the camera. Why not? [That was my first choice] But it will show if nearly pointed at you. But the beam only shows when it crosses a physical object...like the hull, or, in various other shots, the hull and fish. Why so? The light beam is not falling on the hull at all. Why the gap?