It is said that it will take more than 100 miles to Zhenzhou one way, and Hong Tao and Chen Mingen have discussed this issue several times, but they have not figured out how long this Li of the Song Dynasty is. Because there was no clear official regulation of this unit in the Song Dynasty, in the Song Dynasty's unit of weights and measures, the highest was quoted. One lead is equal to ten zhang, one zhang is equal to ten feet, one foot is equal to ten inches, one inch is equal to ten, and then the top and bottom are gone. This kind of unit was still formulated by the Qin Dynasty, and it has not changed much since the Qin Dynasty, at least in the Song Dynasty, and the official regulations are these five units.

Hong Tao himself converted, if ten leads equal to one mile, only more than 300 meters, a little short, according to the hexadecimal system, from 16 to one mile, should be more than 480 meters, almost consistent with the modern city. In fact, if Hong Tao learns history better, he should know that he miscalculated, there was a record in ancient books, before the Qing Dynasty revised the length unit, each dynasty was based on eighteen citations as one mile, as for why, it is not clear, anyway, it is recorded like this. In other words, the Song Dynasty Li was slightly longer than the modern city, about 550 meters.

Whether it's 480 meters or 550 meters, it's about the same anyway, and it doesn't have a big impact on Hongtao, that is to say, it takes about 50 kilometers of sea from Ningyuan River to Zhenzhou. According to the current speed of this small wooden boat, the full sail can run to about 3 knots when the wind is 3 or 4, that is, 5.5 kilometers per hour, which is basically about the same as an adult walking briskly.

Don't underestimate the speed of walking, people need to pay physical strength to walk, can you walk for an hour and walk briskly for ten hours? Don't walk fast, can you walk for ten hours a minute? The sailboat will become, let alone ten hours, as long as it does not enter the windless zone, regardless of the wind and wind, it can go, 24 hours a day, ten days in a row, dozens of days. So don't look at the speed is not fast, in fact, it is still many times faster than a person walking, and it still walks with a load.

When it comes to the speed of the sailboat, Hong Tao doesn't need to ask anyone, and his heart is clear. He studied this matter, and during the examination for the sailing license, he went to the library to check a lot of information, and even the modern and ancient times were a meal, which shows how much effort he can put into playing, for fear that others will ask him. If you ask him if he understands listed companies, he can answer two words without changing his face and heartbeat: no! But if you have to be asked about playing, especially about the project he is playing, then he will feel very shameless.

How fast could a sailboat run in the Tang and Song dynasties? The answer is given in the historical record. Zheng He's treasure ship travels about 100 nautical miles a day, and the average is only more than 4 knots. There is another accurately recorded example, in the late Qing Dynasty, there was an ocean-going sailing ship called the Qiying, which departed from Boston and arrived in London in 21 days, with a total distance of 5,264 kilometers and an average speed of 10.44 kilometers per hour, or 5.7 knots. Not to mention the extreme case of a Category 6 side backwind, then there will be a Category 1 wind when it goes straight to the top.

In the Ming Dynasty document "Records of the Ryukyu Envoys", there are records of envoys to Ryukyu during the Jiajing and Wanli periods, and it takes seven days and nights to travel from Fujian to Shuri (now Naha), and it can be estimated that the speed of sailing ships at that time was about 80 kilometers to 120 kilometers in one day and night.

The above are all the speeds of Chinese hard sailing ships, can European soft sailing ships run faster? This has to be analyzed, and it is recorded that in July 1660, the governor of Batavia sent Van der Laan to the bay with 12 sailing ships, which took 65 days; In 1661, Jacob galloped to the aid of Wanwan. Kaau'u led 10 warships to the bay on 18 July after 38 days, so that it can be estimated that the European soft galleons sailed between 60 and 100 kilometers in a day and night.

It can be seen that the speed of ancient Chinese sailing ships was not fast, in fact, European sailing ships in the Age of Discovery were not much faster. The average speed of the Galen sailing ship is about 7 knots, and the fast sailing speed of the Mediterranean slurry sailing ship can only be about 8 knots, and it can only be maintained for a whole day, and the oarsman will not be able to row for a long time. Even if the extreme sprint can run a speed of more than 11 knots, it can only be maintained for 20 minutes, which is not among the ocean-going ships.

These are ocean-going merchant ships and armed merchant ships, and if they are replaced by warships, the speed of the ships can increase a little, but not too much. Not to mention the British warships at the end of the Qing Dynasty, they were all in the 19th century at that time, and the average speed was less than 10 knots, otherwise they would not have been replaced by steamships that could maintain a speed of 11 knots.

Of course, there are no exceptions, whether it is ancient China or Europe, there are some offshore ships that can run relatively fast. For example, there is a kind of sailing ship with a displacement of about 200 tons on the coast of Fujian, which is locally called Green Eyebrow, with three masts and five or six large sails, and its recorded speed is an average of 9 knots. However, this kind of ship is suitable for warships, and the ship is slender and long, and it cannot carry too much cargo, so it is also called a bird ship.

Then someone asked, when the waves sailed around the world, why did the sailboat run at a high speed of 30 knots? Two words: technology! Three words: high-tech!

The sailing ships of later generations and the sailing ships of the Middle Ages are completely different concepts. The first is the ship type, which is computer-aided and has a small tonnage, which is very suitable for high-speed sailing. The second is the material, from the hull to the mast to the sail, which is both light and tough synthetic material, and the thrust-to-weight ratio of the sail is very large, and it is impossible to find such a good canvas and such a strong mast in ancient times. If the mast is forcibly raised and the sail area is increased, the mast will be broken by the sail before the ship can get up. Finally, it is the use, whether the ancient sailing ship is a merchant ship or a warship, it is mainly practical, and it has to be put on a lot of goods and people, and the modern sailing ship is mainly for play and competition, one or two people can be piloted, without thinking too much about the amount of transfer.

In addition, the use of modern sails is completely different from that of ancient sails, although they look like a piece of cloth, but there is a big difference in substance. Ancient sails were mainly used to sail downwind, which is the limitation of science and technology, they did not understand Bernoulli's principle, and naturally felt that the downwind was faster. In fact, after the invention of the airplane, everyone figured out a technology that uses the principle of the wing to make the sail produce a pressure difference, which is how later sailboats were designed, and it is much faster than downwind in the case of crosswind.

In fact, the speed of modern ocean-going cargo ships is not fast, all of them are more than ten knots, even warships cannot maintain high-speed navigation for a long time, so the machine can't stand it. Therefore, when it comes to long-distance sailing on the sea, the main parameter is the average speed, and high-speed navigation is only suitable for special situations, not that it is not important, but it is definitely not the first place.

At this rate, taking into account the headwind and rest time, Chen Mingen and his team will have to travel from Ningyuan Hekou to Zhenzhou for about 20 hours, and it will take two days to go back and forth, and then they will have to sell and buy goods locally for four or five days before they can come back.