Li Daoyuan's book "Notes on Water Classics" in the Northern Wei Dynasty said: "Since the 700-mile Three Gorges, the two sides of the Three Gorges have been connected with mountains without gaps, and the mountains overlap and cover the sky ...... Sometimes I worship Baidi and arrive in Jiangling at dusk, during which I rode against the wind and didn't get sick."
In other words, Zhu thinks that the distance from Baidicheng to Jiangling is 1200 Li. According to the fourth volume of the traffic map of the Tang Dynasty, the distance from Kuizhou to Jiangling is "three hundred and thirty miles east of Guizhou, two hundred miles east of Zhou Xia and three hundred and thirty miles east of Jingzhou Jiangling House".
According to the records here, the distance from Baidicheng to Jiangling is 864 Li. Due to the limitation of ancient measurement technology, the distance recorded in various documents will be different. To this end, the author measured the waterway distance between the two places on the map. According to the author's measurement, the waterway distance from Fengjie Baidicheng Scenic Area to Jingzhou Binjiang Park is about 345.4 kilometers, which is about 69 1 Li.
The cultural relics unearthed during the Warring States Period all have patterns of sails, which shows that sailing boats appeared in China very early. In Li Bai's poems and songs, there are poems such as "Sailing alone, the sky is exhausted" and "Stand me straight, the bridge is deep in the sea", which shows that sailing should be a very common means of water transportation in the Tang Dynasty. According to documents, sailing boats in China in the Tang Dynasty were able to sail against the wind, with good seakeeping and high speed. During the Zhenguan period of the Tang Dynasty, it took only six days from Wenzhou to Japan.
The author measured the distance from Wenzhou to the southernmost tip of Kyushu Island in Japan, which is about 1000 km. Roughly speaking, the sailing speed of sailboats at sea is about 7 kilometers per hour. Because of the rough sea, the speed of 10 km to 20 km should be reasonable when sailing on a calm river. With the help of the downwind, the ship can go faster.
Li Bai was in a good mood after being pardoned. He set out by boat at dawn, hummed and sang songs, drank and entertained, enjoyed the magnificent scenery of the Three Gorges of the Yangtze River, listened to the cries of apes on both sides, and then arrived in Jiangling at midnight.