There are usually lighthouses along the coast. What are the functions of these lighthouses?

Most lighthouses are tower-shaped buildings that can emit light. According to the size, location and characteristics of lighthouses, they can be divided into manned lighthouses and unattended lighthouses, which are mainly distributed in coastal areas, important waterways, important islands and other important places where lighthouses need to be set up. The beams from the lighthouse are parallel. There are certain light scattering angles according to the situation, such as 30 degrees, 45 degrees and 60 degrees. The colors of lights are red, green and white. The light lasts for a long time, or lights intermittently at a certain time, and the range can reach 20-30 nautical miles (37-56 kilometers).

From ancient times to the present, the biggest function of lighthouse is to guide ships to sail, indicate safe navigation channels and directions, mark dangerous areas, dangerous coasts, sandbars and reefs, and provide guarantee for the safe navigation of ships.

In the past, lighthouses were also called sea beacon towers. They are built into forts and forward bases for military purposes, such as coastal defense and maritime defense. Built on an island far from the coast, you can also swear sovereignty. For example, in China's Nansha Islands, some islands were first built as lighthouses to swear sovereignty in the name of ship safety.

However, with the development of science and technology, new technologies are applied, such as radar transponder, GPS positioning and navigation, AIS automatic ship identification system, ECS electronic chart, radar navigation and so on. Ships sailing at sea do not rely on lighthouses for navigation. The traditional role of lighthouses is gradually weakening and the navigation value is decreasing. Because the reliability and stability of electronic equipment will be disturbed, lighthouse has gradually become an indispensable supplement after electronic navigation equipment. The role of tradition has been reduced, and the lighthouse has gradually become a unique landmark sought after by people. With certain historical and cultural value, it has become a tourist punching resort. Such as China Zhejiang Flower and Bird Mountain Lighthouse, Dalian Laotieshan Lighthouse and Hainan Lingao Lighthouse.