Anyone who has to be — or might be — boating after dark should have a spotlight on board. You’ll need one to pick your way through floating debris, find gear or even locate a man overboard. Lacking scientific equipment to verify manufacturer claims of light output, we stood at the end of our street and illuminated a stop sign one-eighth of a mile away. We also shot the beam into the sky, noting the resolution of the beam and the apparent reach. In pure orneriness, we also blinded our co-workers across the hall.