Final answer:
Navigation lights should be displayed in restricted visibility conditions, such as fog, to make vessels visible to others and to prevent collisions, similar to the role of lighthouses and car headlights in providing safety and orientation.
Step-by-step explanation:
Navigation lights should be displayed in periods of restricted visibility, such as during fog, to ensure that vessels can be seen by other watercraft. The importance of navigation lights is akin to using headlights on your car in foggy conditions. Not only does it make your vessel visible to others, but it also helps you observe any nearby threats or navigational markers, much like gas lamp light cuts through the darkness and fog in streets, or how the distant light from a lighthouse signals to ships the edge of a dangerous shoreline.
The rules for displaying navigation lights in such conditions are governed by marine laws and regulations, which typically mandate their use from sunset to sunrise and during periods of reduced visibility such as fog. The concept behind these requirements is alluded to in various descriptions of visibility on the sea and on land: light provides orientation and safety. Reference to a lighthouse or searchlight beams made visible by colloidal particles in the air also demonstrates how lights serve as crucial navigation aids.
Therefore, whenever visibility is compromised, vessels must show appropriate navigation lights to alert other vessels of their presence and to prevent collisions, just as a lighthouse warns ships away from perilous coastlines through the use of its rotating light beam.