"There is a plum wind in May, and the south of the Yangtze River is a trade wind."

On the merchant ship of Bashang, the old captain with dark skin stood on the deck of the stern building and said in the face of the vast sea. The plum wind was the southeastern monsoon that appeared after the plum rain season. During the Han Dynasty, people already knew how to use the monsoon to sail.

"But in the past, people were relatively passive about the interest rate on the monsoon. In the past, we set sail and sailed to the Southeast monsoon in the summer. After we got there, we sold the goods but couldn't return. We still had to wait until the northwest monsoon in the winter to return, and we waited for five months."

Cheng Yaojin chewed a piece of beef jerky and looked at the seagulls on the sea absent-mindedly.

He used to be a landlord and didn't know what kind of leap in navigation. He didn't even know how big a leap in navigation technology today.

"The biggest reason why sea trade was not as prosperous as it is now is not ships. Shipbuilding technology is not the key, but navigation technology. At that time, there was no compass compass or sextant positioning. It was all about luck to sail on the sea, and it was not an exaggeration to say that it was a gambling life."

A route and a sea chart are the most precious treasures, and they are definitely treasures treasured by a sea merchant family for generations. Moreover, such a picture is only mastered by the captain. Even if the helmsman and others sail the entire journey, they cannot master it. Because they don’t know how to identify the direction, and they don’t even know where they are.

Only the captain can master the route and positioning, which they have learned little by little with the old captain over the past few decades. A qualified captain must be very familiar with the natural objects in the sea surface and the sea, such as birds, fish, water flow, driftwood, seaweed, water color and even clouds, wind, etc.

Some captains always put a cage of crows on the boat. When the captain feels that it is approaching the land, he will release the birds in the cage. If the crow flies aimlessly around the boat, it means it is still far from the land. If the crow flies in a certain direction, he will drive the boat to follow the crows, which must be the direction toward the land.

In the past, even if they were very experienced captains, they only ran a fixed route in their lives. Because their experience and the route charts in their minds were actually summarized by their predecessors, they were fixed route maps, not methods to find.

The entire route map is referenced by countless fixed targets. If it deviates from a reference object, it may be lost on the sea. It is impossible to let them run an unfamiliar route.

"In the past, when I traveled to the South China Ocean, I always had to carefully sail near the shore, and judge and correct the navigation through the land characteristics we could see. We even only sail during the day, and park in the harbor or anchor on the sea at night. We would rather sail around the coast than dare to rudge southward."

"My teacher has always warned me not to venture out to sea to the ocean where there is no sight of land. Because the danger of encountering reefs and shallows along the coast is higher, but it is terrible than being lost and sunk in the sea."

Cheng Yaojin asked, "You can't grasp the direction. Look at the stars or something. Are you just judging the direction through the stars now?"

"I didn't have this ability before."

The old captain said very directly.

At that time, everyone sailed along the coast, fearing that they would lose their direction, fearing that they would storm in the ocean, and fearing that they would pirates. But in the final analysis, the most important reason is the first reason.

Now, Li Chao invented the compass and sextant, so everyone can accurately find the direction at sea and know their location. Even if there is a threat from ocean storms and pirates, the captains dare to sail through the ocean.

"For example, we went to Baekje Silla and sailed directly from Dengzhou to the east. It only took three days to get there when we were on the wind. But before, few people dared to cross the ocean like this. They all went through the Wuhu Islands to the southern Liaoning, then followed the eastern coast of Liao to the Sanhan Peninsula, and then continued along the coast to Silla. They took a huge turn, and the three-day voyage may take two or three months."

Only those who have been running on the sea for many years like the old captain can truly understand the greatness of the compass and sextant invented by Li Chao. Sailing on the sea, especially for long-distance voyages, is the most important thing to determine the direction of the ship.

In the past, people used to judge their position by observing the height of the sun during the day and the direction of the North Star at night. However, the error was still huge. In the vast ocean, a little error can sometimes be a slight mistake, and it will be a huge mistake.

Especially in the harsh weather, the sun and the North Star cannot be seen. So later, a simple compass was formed. A iron needle was rubbed on a magnet to produce magnetic properties, and fixed it on a straw and suspended it in a bowl of water. In this way, the magnetic iron needle would automatically point to the north.

The compass invented by Li Chao is actually an improved type. The nautical magnetic compass can continuously measure all horizontal directions, with an accuracy of less than three degrees.

When Li Chao's nautical compass was first launched, many captains thought that this thing was very mysterious and did not believe it very much. However, they later found that the compass was very stable and reliable, so they quickly became popular again.

The complex moment and the star-pulling plate are all positioned using the height of the North Star. However, the error of these instruments is still large. Li Chao took out a sextant and used it to measure the angle between the sun and other celestial bodies and the sea or horizon at a certain moment, so as to quickly understand the longitude of the sea ship.

The sextant has a fan-shaped appearance, and the components consist of a small telescope, a semi-transparent and semi-return fixed plane mirror, and a movable reflector connected to the indicator.

When in use, the observer holds a sextant and rotates the indicator mirror to make the celestial objects that appear simultaneously in the field of view coincide with the horizontal line.

The advantage of this instrument is that it can be observed on a swinging and undulating boat, but the disadvantage is that it cannot be used on rainy days.

However, even so, the high-precision sextant has quickly become a necessary equipment on long-distance ships.

With the nautical magnetic compass and sextant, you don’t have to worry about losing your way or not knowing where you are. Even if you can’t sail in rainy days, it’s only temporary. You can temporarily get off the anchor and wait, or correct your course when there is good weather.

"There is another reason why we dare to go deep into the ocean now, that is, our sailing technology has also been greatly improved. We can now wind from all directions, and except for the direction in the head, the ship can sail in the other seven directions. Therefore, even if there is no monsoon to take advantage of, we can sail, and we can sail against the wind and crosswind. As long as there is wind, we can sail, the difference is just speed."

Under the promotion of Li Chao, Datang's navigation technology has made rapid progress and shipbuilding technology has also made leaps.

The centerline rudder makes the ship's steering more convenient and fast, and the watertight cabin greatly improves the safety of the ship. Technology such as soft sails, splicing keels, splicing masts allow the ship to build larger, allowing the ship to be windy from all sides. Compasses and sextantes allow the ship to no longer lose its direction.

It can be said that Li Chao has improved the navigation technology for a thousand years, allowing the Tang Dynasty's sea ships to sail from near-sea to being able to go directly into the ocean. Although there are no Tang ships to sail across the ocean yet, under these new technologies, sooner or later, adventure captains will sail to the depths of the ocean to explore more unknown places.

Among them, the midline rudder is an important technology that is not weaker than the compass. Only by pairing with a new sail can the midline rudder flexibly change direction so that the ship can be exposed to the wind at a favorable sail angle.

Without an efficient vertical center line rudder, the ship will not have the ability to sail far. It can only sail simply by taking advantage of the monsoon. For example, the old captains used to rush into the South Ocean in summer, and then they have to wait until the winter wind blows, and it will take more than half a year to return to voyage.

Now, with the new sail and the centerline rudder, the sea ship can sail far away from all sides and upwind and sideways.

In recent years, Li Chao has spent a lot of manpower and material resources to send crew members to measure the hydrological geography and other situations along the coast of the Tang Dynasty, and has drawn many navigation charts.

These things that were extremely rough in Li Chao's eyes were treasures that the captains dreamed of.

"Are there any pirates on this sea?" Lao Cheng was not very interested in navigation technology. He was interested in pirates.

"Yes, it's available everywhere along the coast, but no one dares to rob our ships."

Like the pirates in the mainland, there is no shortage of pirates at any time. Especially after the war at the end of the Sui Dynasty, the Central Plains were pacified not long ago, and there were many pirates, but there were no more powerful ones.

Li Chao and his team are all great, and ordinary pirates are just small sailboats, so how dare they rob them? Besides, the emblems hanging on the ship can ensure that no one dares to come.

"They dare not come and rob us, we will rob them. Do you know where there are pirates nearby? Let's take them and practice first." Lao Cheng said with no trouble. "We are all teenagers on our ship, and we don't see blood. These people are useless when they arrive in Goguryeo."

Seeing that Lao Cheng was so persistent, the captain looked at Li Chao.

"What Duke Lu said is also some truth. It's better to find a few nests of pirates to practice first."

From Dengzhou to Liaodong Peninsula, the nearest route is to fly directly, because there are many archipelagos in the middle, so there is no need to worry about losing direction. However, it is precisely because of the many islands here that there are many pirate activities.

In fact, these pirates did not make a living by robbery. Some were refugees who fled the Central Plains during the Sui Dynasty, some anti-army escaped after failed rebellion, and of course, some were smuggling fleets of local tyrants.

There are many teams and various types of islands in the Wuhu Islands.

"Double miles north of this place, there is a snake island with many snakes on it. In recent years, a pirate has occupied the island and called itself the Red Viper Pirates. There are about ten boats, and there are about a thousand people in the family." The captain has been running this route for more than a year and is quite familiar with the situation of the pirates here.

The pirate group with more than 1,000 people is not weak. But if the family members are left alone, the old and weak are actually only 200 or 300 real pirates.
Chapter completed!