Weems & Plath Lightrule. # 190. If you have ever been on the water at night and wondered if the lights you see are from an approaching or fleeing vessel or if you wonder if the vessel is a fishing trawler or super tanker then the lightrule is for you. This simple to use vessel identification tool shows the actual view of vessels for Port, Starboard, Bow and Stern lights. Identifies 60 light configurations and provides a magnifying lens to make vessel descriptions easy to read. Also displays audible signals for restricted visibility, maneuvering and warning. Constructed of extremely durable plastic and stored in a vinyl sleeve.