After sending away the vassal kings, Zhu Youxiao began to concentrate on transforming the naval fleet of the Ming Dynasty, the current naval fleet is mainly concentrated in the southeastern coastal areas, the artillery of these fleets is also old-fashioned solid bullets, and the current combat method is mainly based on boarding and fighting, for directly sinking the opponent's ships is still not too much, the key is that the power of the cannonball is too small, unless the large fleet encounters a small ship, it can be directly sunk.

Some of the veterans of Qi Jin's army grew up on the ship, so after Sun Chengzong and Qi Jin returned, Zhu Youxiao decided this issue in the first place. Zhu Youxiao meant to directly reorganize Qi Jin's troops into a navy, these elite soldiers were all fought the battlefield, and they had a good psychological quality, plus they were also familiar with the application of new artillery, so that they could quickly form an army and quickly form combat effectiveness.

Qi Jin was very happy that the emperor wanted to convert his troops into a navy, which showed that the emperor attached great importance to himself. Since the beginning of the fight against the Japanese pirates, the Qi family army has always attached great importance to the training of naval soldiers, otherwise there would not have been an absolute victory in the encirclement and suppression of the Japanese pirates at sea. But since the Qi family army was transferred to Jizhou, there are no more naval examples, only the land war Mongols are left, and its results are brilliant over the naval battle, but this does not mean that the talent in naval warfare is gone, but it has become a talent in both naval and land battles, which is the reason why Zhu Youxiao attaches more importance to the Qi family army, plus now the Qi family army has become a Shenji battalion after the expansion, and it will be trained in the future to be the prototype of the standard Ming Dynasty marines. In this way, this army will be the elite of the Ming Dynasty, whether it is naval or land warfare.

The first thing to build the navy is to build warships, the current warships are all wooden, and what Zhu Youxiao wants to build is a warship made of steel, but for the current steel production and quality, this thing is not very realistic, so Zhu Youxiao can only move forward step by step like in history, and the first thing to build is the ironclad fleet. But even so, the problem of the power of the fleet was not easy to solve, and the power of the steam engine was still small. With the joint efforts of Zhu Ling and Song Yingxing, Xu Guangqi and Bi Maokang, after nearly half a year of research and experiments, they found that there is an important problem that is not easy to solve, that is, the lubrication problem, at the joint point of the crankshaft connection, there is often a heating phenomenon, resulting in too high temperature and too short service life, Zhu Youxiao thought about it and told them to try it with castor oil or rapeseed oil, and the final experimental result was that castor oil had a better effect. In addition, there are also problems such as the speed regulation of the steam engine, the temperature of the cylinder, the transmission power, etc., which will not be solved for a while. Although Zhu Youxiao has a solution to these problems, he still didn't say it directly, he was afraid that what he said too much would hinder the thinking ability of these bulls, so that they could form the habit of looking for the emperor if they couldn't solve the problem, but he also talked about the clutch and transmission principle. The other Zhu Youxiao just let them find problems in the process of practice, and then solve these problems, even if they lost the time to build ships and delayed them backwards.

After such a long time, Zhu Ling and the others finally built a practical steam engine, although the power is not too high, but if it is used on a relatively small ship, it can still be used as power. In order not to waste too much material, Zhu Youxiao decided to use this practical primitive steam engine as a model, and trial produced twelve of the same steam engines to test the third-class fortune ships of the Ming Dynasty, and built a total of three such ironclad ships, each using four steam engines. The fortune ships of the Ming Dynasty were divided into five levels, the largest was nearly 20 zhang long, four zhang wide, six zhang high, and the smallest was also four zhang long and one zhang wide. The first-class fortune ship is not used to make a warship, it is equivalent to the current supply ship, the second-class fortune ship is used to make a battleship, and the design is relatively strong, and the third-class fortune ship is used to patrol the sentry and travel at a relatively fast speed.

Zhu Youxiao chose a third-class lucky ship twelve zhang long, three zhang wide, and five zhang high to do the experiment. Because the second-class ship is too big, Zhu Youxiao is afraid that there is a problem with its structure, and he can't help the shock of the cannon, in case the warship is damaged when the cannon is fired, it will be a big joke, especially now that there is no suitable way to calculate the bearing capacity, Zhu Youxiao can only take a more secure method. In order to be more secure, Zhu Youxiao also asked Song Yingxing to make four ten-zhang long steel columns and put them in the keel to strengthen the seismic performance of the Fu ship, and then use these four steel columns as the keel to add horizontal thin iron columns. Originally, Zhu Youxiao planned to use steel pipes, but now it is too difficult to make steel pipes of such lengths, so he has to use steel columns instead. Outside these steel keels, ordinary wooden keels are normally used, so that this third-class Fu ship uses double keels, and the cannon is designed at the front and rear ends of the Fu ship, and the side is not set up with cannons for the time being, each Fu ship is designed with eight cannons, four in the front and rear, and a mortar in the middle to defend, and the Fu ship built on this basis can naturally withstand a relatively large cannon vibration. Now the use of solid bullets is basically solid, or to climb the gang battle as the main way, so still around the ship wrapped an inch thick steel plate, the deck is also laid an inch thick steel plate below, so that even if the solid bullet hits the ship, after the shock absorption of the wooden plank, the steel plate can completely protect the hull from damage, and prepare some sandbags to prevent the iron bullet from rolling and hurting people. After the addition of steel armor, the weight of the third-class ship naturally increased a lot, almost the same as the weight of the second-class ship, but because of the steam engine as the power, Zhu Youxiao still had great hopes for these three ironclad ships.

Because the main firepower of these three third-class ironclad ships is at the front and rear ends, they face the enemy head-on when fighting, and because they are protected by steel plates, they can withstand the enemy's solid bullet smashing, so they are required to fire when they are close to the enemy, so as to get the highest and best shelling effect, because all of them are *, and the current trigger fuse is not very good, and it must touch the opponent's ship to explode, so it is basically about a mile away to start firing. For the current ordinary wooden ships, the largest is only twenty-four zhang long, five zhang wide, which seems to be only about two zhang in size outside five miles, with the current shooting accuracy, the probability of hitting the cannon at this distance is less than one thousandth, even if the upper gun mirror and calculation tools are used, the hit rate will not exceed five thousandths, and these three ironclad ships mainly face the enemy with a frontal bow, relatively speaking, the attack area is smaller, once close to the opponent about a mile, plus the help of the gun mirror, The hit rate should reach 50%, especially if the opponent shoots with a side chord with a larger area, the hit rate will be higher, although the opponent's hit rate will also increase, but the ironclad ship's attack resistance is better, and the attack area of the solid bullet is very small, the lethality of the attack can cover almost one-tenth of the area, and the mortar has the best range at this distance, so that if the ship's cannon and mortar attack an enemy ship at the same time, it can sink it in one turn.

Zhu Youxiao also asked the ironclad Fu ship to be equipped with four hand-cranked machine guns, if the other party approached the Fu ship, he could also use the machine gun to strafe at close range, which was an absolute nightmare for the opponent who was equipped with a broadsword and breech gun, not only could not rob his own ship, but also sent their ship to the door, so that he could also have the money left for his own shipbuilding.

Qi Jin and his soldiers had to train on the old warships before the new ironclad ships were built, and under the coordination of Zhu Youxiao, some of the old ships were transferred from the south. Qi Jin encouraged the soldiers that all officers and men with outstanding training achievements will give priority to taking over new-type warships, and the power and life-saving chances of new-style warships are countless times higher than those of old-style warships.