Let's take a look at an ancient text.
Huizi said of Zhuangzi: "The King of Wei is the seed of my great urn, and the tree of mine is formed, and the five stones are solid." To hold the slurry, its firmness can not lift itself also. If you cut it into a scoop, you will fall into nothing. I am sorry for its uselessness. Zhuang Zi said, "Now that I have five stones, why don't you worry about thinking that it is a big bottle, and floating in the rivers and lakes, and worrying about its fall and having no room?" (Cited with abridgement)
This is the story of Huishi and Zhuangzi. The gist is that the King of Wei gave Huishi a gourd seed, the big gourd that came out can hold five stones, used to hold water, the texture is too brittle, cut open when the scoop, flat and shallow can not hold things, I simply smashed, Zhuangzi said, you have such a big gourd, why not consider tying it on the waist, floating and above the rivers and lakes.
This is probably an earlier idea of a ship.
In fact, as early as zhuangzi, Confucius said, "The Tao is not working, and it floats on the sea." "What Confucius is talking about here is probably a raft or something.
However, it can also be seen that both Confucius and Zhuangzi did not know much about boats, and in their earlier Western Zhou, there was a record of boats, "Where the water travels and the mountains are, the boat is the car, the boat is the horse, and it is difficult to go to the wind." Pay attention to this "to the wind, to go is difficult to follow", which shows that the ships at that time were OK when they went down the water, and it was a little difficult to sail against the current, it seemed that the ships at that time were still relatively small, and it was difficult to cross the ocean.
If you want to go to the ends of the earth, you have to have a sailboat.
1. The crowd paddles and drives the big boat
Speaking of sailing, we must first think of "borrowing the east wind", indeed, only sailing ships need to use the wind, if they are all rocking oared boats, there is no need to "borrow the east wind" during the Battle of Chibi.
However, at that time, the ships still had to be rowed, and when the wind was downwind, they pulled the sails and sailed away, and when the wind was headwind, everyone rowed oars to open the big boat, so the ships at that time could not be built without strong national strength.
The Yuan Dynasty once waved fusang to conquer this small overseas country, but above the sea, a gust of wind blew away the yuan dynasty water division, and the small country of Fuso survived, so Fusang publicized kamikaze every day, so that during World War II, it also played the "kamikaze" operation.
The pinnacle of Chinese shipbuilding is in Daming. In the Battle of Poyang Lake, Zhu Yuanzhang defeated Chen Youyi's powerful water division with weak troops, which can be regarded as another Battle of Chibi, this water war is simply a copy of the Battle of Chibi, first Of all, Chen Youyu trained the warships into a piece, secondly, there was a strong wind blowing on Poyang Lake, and finally, Zhu Yuanzhang attacked with fire, of course, it may also be that Luo Guanzhong processed it according to the situation of the Battle of Poyang Lake and put it into the Romance of the Three Kingdoms.
It is still necessary to talk about Zheng He's voyage to the West, and zheng He's treasure ship in the West is not only the peak of China's shipbuilding history, but also the peak of the world shipbuilding industry at that time.
Treasure ship model
According to the Yingya Victory, "There are sixty-three treasure ships, the largest is forty-four feet long and 18 feet wide, and the middle one is thirty-seven meters long and fifteen meters wide." Gong Zhen, who accompanied Zheng He to the West, recorded in the "Chronicle of the Western Fanguo": "The treasure boat he rides on is majestic and invincible. Peng, sails, and rocking cannot be moved by two or three hundred people. "This is already a sea giant, equivalent to today's aircraft carrier."
Zheng He's fleet
This is Zheng He's treasure ship, the sails on the treasure ship are perpendicular to the hull, so it is also called horizontal sail, in order to ensure greater wind, the sail is also made of quadrilateral, in the downwind, naturally it is vast, across the sea. However, such a treasure ship, when sailing far, can only rely on the coastline to travel, it is difficult to cross the ocean, what is the problem?
The problem lies in the sails, whether it is Zheng He's treasure ship, or Cao Cao's sternwheeler during the Battle of Chibi, all of which are horizontal sails, that is, four-corner sails, the advantage is that they are easy to operate, the wind is large, and the disadvantages are also obvious, that is, they can only go with the wind, and when they are headwind, they can only drop the sails and move forward by human paddle.
Above the sea, the climate is unpredictable, and it is difficult to travel against the wind after all, so Zheng He's Western Ocean mostly relies on coastline navigation, at least when the wind is strong, it can be repaired on the shore.
If you want to cross the world, there must be new technologies.
2. Cross the ocean to see you
This new technology is the spinnaker, and the dhow sail arrangement is parallel to the hull direction, so it is also called a longitudinal sail.
Spinnaker sailboat
In the end, the spinnaker is not a new technology, it has been in the Arab world as early as the Arabs, it seems that so many sailing stories in "One Thousand and One Nights" are not just legends, and the Arabs at that time had the ability to cross the ocean. But the popularity of the spinnaker was still in the age of great navigation.
So how does the spinnaker fly against the wind?
Let's start with a story.
In 1912, the ocean-going freighter Olympic was sailing on the high seas. An ironclad cruiser, the Hauk, caught up from behind, causing the Olympic to hit a large hole in its side.
This is definitely a serious maritime incident. Afterwards, in the maritime court, the captain of the Hauk claimed that he never gave an order to turn the rudder, and the sailors of the Hauk proved that they could not change the ship's collision with the Olympia no matter how they operated. So what's going on? Is there really a ghost?
There really is a ghost, and this ghost is Bernoulli's principle. What the hell is Bernoulli's principle?
Let's review the physics knowledge, in middle school we all did an experiment, that is, with the mouth to blow two pieces of paper, the result is to blow closer and closer.
This is actually bernoulli's principle, by Daniel. Bernoulli asked why he should say his full name, because his surname is too great, his uncle, his father and his brother are scientists, if you don't say the full name, it is really difficult to say which Bernoulli, but his legendary family is different, other families such as the Curie family are united, the Bernoulli family is a conspiracy.
Well, back to the Bernoulli principle, the Bernoulli principle is simply in the flow of water or air, if the speed is small, the pressure is large, if the speed is large, the pressure is small.
This is very common in life, use the above paper blowing experiment to talk about it, because the blowing makes the air flow speed between the two sheets of paper faster, then the pressure in the middle of the paper becomes smaller, and the pressure on both sides of the paper does not change, naturally the two pieces of paper are pressed together.
When the "Hauk" and "Olympic" are parallel, the water flow between the two ships is fast, it is as if we blow air into the middle of two pieces of paper, according to bernoulli principle, the speed is fast and the pressure is small, and the water velocity on the outside of the two ships is slow and strong, so that the pressure difference between the two ships will make the two ships close, because the "Hauk" is much smaller than the "Olympic", so it looks like the "Hawker" crashed.
Similarly, when the train enters the station, the station staff always advises everyone to be outside the yellow line, but also to avoid everyone taking the initiative to "crash" into the train.
Airplanes fly using Bernoulli's principle.
The principle of flight of the aircraft
This is a cross-section of the wing, when the plane is taxiing on the runway, the time for air to pass above and below the wing is the same, but because the wing is curved above, the distance is a little longer, so it is a little faster, it is like two people racing, one person running along the runway, one person interjecting from the middle of the playground, to arrive at the same time, the students running along the runway should be faster.
Since the air flow rate above the wing is fast, according to Bernoulli's principle, the pressure is naturally small, so that there will be a pressure difference between the bottom and the top of the wing, and this pressure difference will support the aircraft.
Explaining the principle of the aircraft, it is easy to say that the sailboat is headwind, because this is to put the wings up.
Spinnaker
On the left, is the bulging spinnaker, because the air flow speed of the leeward surface is fast, the pressure is small, and the slow pressure of the windward air flow speed is large, which is the same as the aircraft wing mentioned above, so that it will produce a thrust facing the leeward side, because it is a vertical sail, that is, the sail and the hull are parallel, and the ship will be pushed towards the leeward surface, which is the same as the "Hauk" crashing into the "Olympic" principle.
If we push it all the way down, the boat may overturn, although we call it a sailboat but not to overturn the boat, so we will adjust the direction of the bow.
In this way, the sailboat can go forward, and the specific navigation method can be seen in the picture below.
The red arrow is the direction of the wind, and the sailboat is like this zigzag sailing forward.
So why can't the cross sail, or the four-pointed sail, go this way? First of all, the horizontal sail is perpendicular to the hull, of course, you can adjust the angle of the sail by adjusting the sail cable, but you can't adjust too much, otherwise it will become a vertical sail, then simply use the vertical sail, so you can also go against the wind, but because it is a four-corner sail, it cannot form a streamlined profile similar to the wing, so the utilization efficiency of the wind is very low.
If two dhows and quadrangles with similar speeds when going downwind, the speed difference can be 4-5 times when going against the wind, so in the sea where the wind direction changes, the spinnaker is more dominant.
It is precisely because of the emergence of dhows that it is possible to cross the ocean, and Columbus Magellan drove a sailboat and began the era of great navigation.