The important achievement of Zheng He's voyage to the West was that Zibao Shipyard drew a map of foreign countries sailing from Longjiang Pass. The whole map adopts the traditional landscape painting method of China, and is accompanied by recorded needle track and star map crossing the sea. It started from Nanjing, reached the farthest point of Slow Bazaar in Kenya, East Africa, until about four degrees south latitude, including Asia and Africa, and collected more than 500 place names, of which about 300 came from Asian and African countries. The distribution of routes, voyages, berthing ports, reefs and shoals is recorded quite accurately, and many new navigation channels opened by Zheng He during his voyage to the West are recorded in detail. There are more than 20 important navigation sites and 42 main routes. It fully proves that Zheng He's voyage to the Western Seas has effectively promoted China's developed maritime career and enriched China people's understanding of the world.
According to Zheng He's nautical chart, Zheng He's use of hydrological needle (24/48 azimuth compass navigation) combined with star-pulling (astronomical navigation) was the most advanced navigation technology at that time. Zheng He's fleet navigated with a compass during the day and kept its course by observing the stars and the water compass at night. By reasonably solving the problems of fresh water storage, ship stability and anti-sinking, Zheng He's fleet was able to "keep the Yun Fan high and the stars gallop day and night" under the sinister conditions of "Hong Tao meets the sky and the waves are like mountains", with few accidents. During the day, flags of various colors are hung and waved in the agreed way to form corresponding semaphores. At night, lanterns are used to reflect the sailing situation. In case of fog and rain with poor visibility, gongs, horns and horns are also used for communication. Zheng He's skills in going to the West are mainly manifested in three aspects:
1, astronomical navigation technology China can determine the position and navigation direction of ships by observing the sun, moon and stars very early. Zheng He's fleet combined the astronomical positioning of navigation with the application of navigation compass, which improved the accuracy of determining the position and course of the ship. People call it "picking stars". By observing and positioning with the "star pulling board" and measuring the height of the sky, we can judge the position and direction of the ship and determine the course. This technology represents the world advanced level of astronomical navigation in that era.
2. Geographic navigation technology The geographic navigation technology of Zheng He's voyages to the West is based on marine scientific knowledge and nautical charts, using navigational instruments such as navigational compasses, log meters and bathymeters, and determining the navigation route of ships according to the records of nautical charts and needle road books. When sailing, the navigation route is determined, which is called needle track. The compass error shall not exceed 2. 5 degrees.
3. The reason why Zheng He's nautical charts were handed down from generation to generation benefited from the inclusion of Mao in Wu Beizhi, a writer in the late Ming Dynasty. The original picture is a zigzag long scroll, which was changed to calligraphy when Wu Bei was included. From right to left, there are 20 pages of pictures, 40 of which are * * *, and finally two pictures of "crossing the ocean to lead the stars" are attached. More than 530 place names were recorded in the chart, including 300 foreign place names and the farthest east African coast 16. Cities, islands, navigation marks, beaches, reefs, mountains and air routes are all marked. Among them, Nansha Islands (Wansheng Shitangyu), Xisha Islands (Shitang) and zhongsha islands (Shixing Shitang) are clearly marked. 1947, the Ministry of Interior of the Republic of China named the South Island Reef after Zheng He and others to commemorate this great navigator. Zheng He's nautical chart is the earliest existing nautical atlas in the world. Compared with the most representative Portland charts in the west at the same time, Zheng He's nautical charts have a wide range and rich contents. Although its mathematical accuracy is low, its practicability is better than Portland diagram. British Joseph Needham pointed out in his book "History of Science and Technology in China" that Mills and Bladden made a detailed study on the accuracy of China's nautical charts. Both of them are familiar with the entire coastline of Malay Peninsula, and they spoke highly of the accuracy of China's nautical charts. The brilliance of China's advanced navigation technology reflected by Zheng He's voyage to the West shows the great wisdom of the ancient people in China, thus creating Zheng He's voyage to the West.