Centuries of Hainan fishermen's wisdom: how the handwritten "Genglubu" guided ships across the South China Sea without GPS
In the age of satellites and digital maps, it is hard to imagine that just a few generations ago, sailors set out into the open ocean without a single electronic device, relying only on the wind, the stars and the worn pages of a handwritten book. "Genglubu" is not just a navigation manual but a living memory of a people who for centuries explored the waters of the South China Sea, passing down knowledge of currents, reefs and safe routes from mouth to mouth and hand to hand. This documentary is a tribute to their experience and a reminder that the sea is read not only by instruments but also by the heart.
The documentary "Genglubu: Charting the South China Sea" premiered on Thursday on China Global Television Network (CGTN). The film shows how generations of fishermen in the southern Chinese province of Hainan sailed the South China Sea for centuries without GPS or weather forecasts, relying solely on a handwritten manual known as "Genglubu". Incomprehensible to outsiders, it was an invaluable navigation guide and one of the most important items fishermen took on board.
"Fishermen from Tanmen dive into the sea and fish themselves. Finding the best reefs means catching more fish. That is why we keep coming back to the South China Sea. My grandfather and father studied it like homework before going out to sea," said Wang Zhendong, curator of the Genglubu Museum in Qionghai, Hainan.
Wang cannot personally decipher the ancient manuscript, but he understands its importance: his father studied it before every voyage, and his grandfather entrusted it with his life. "When electronic equipment fails, if you don't understand navigation, how can you get everyone home safely? A captain needs experience. Where does that experience come from? It comes from Genglubu. It is ancient knowledge recorded from generation to generation," said Wang Shubao, Wang Zhendong's father.
For generations, this knowledge was recorded in the Genglubu. "Geng" denoted both time and distance travelled at sea. One "geng" meant about two hours of sailing or roughly 10 nautical miles. "Lu" referred to compass bearings and directions, while "bu" meant "book". Without modern instruments, fishermen learned to read the sea – its currents, depths and ever changing moods. One line reads: "From Tanmen port to Zhaoshu Island (Tree Island of the Paracels), follow the direction of Qian, Sun, that is, northwest."
It covers a distance of about 150 nautical miles. Just a few lines, enough to guide a boat across the open sea. One surviving manuscript, copied by Wang Shitao, records 279 routes, making it one of the most detailed versions of Genglubu known to date. Its routes connect Hainan with island groups in the South China Sea, and some extend even further.
"Before Zheng He's voyages (1405–1433) to the Western Seas, fishermen were already working in these South China Sea waters," said Zhou Weimin, a professor at Hainan University. Experts say Genglubu is not just a practical navigation guide; it is also a chronicle of China's maritime history, its cultural heritage and the accumulated wisdom of a people shaped by the sea.
"Genglubu is a navigation guide created based on years of experience. It is an integral part of China's maritime system. It is cultural heritage created by our ancestors and an embodiment of the wisdom of a people with long standing maritime traditions," said Liu Yijie, a professor at the Fujian and Taiwan Studies Centre at Fujian Normal University. Genglubu is recognised as an important intangible cultural heritage of China. Its uniqueness lies in its oral and written transmission over many centuries, preserving knowledge that remains relevant in the modern era.
As CCTV+ reports. The CGTN documentary aims to introduce this remarkable phenomenon to a global audience, highlighting the deep historical roots of Chinese navigation and its significance for understanding China's sovereignty in the South China Sea.
