"For a unit, changing equipment means the transformation and enhancement of combat effectiveness of the entire unit," said Wang Lei, who has served in a submarine unit of the Chinese Navy for 12 years, referring to the significance of changing equipment for the unit. The term "replacement" in the Chinese military refers to the process of replacing existing weapons and equipment with new ones. It is an important activity to optimize equipment structure, gradually implement the military equipment system, and also an effective way to improve the combat effectiveness of the troops. The reporter recently visited the birthplace of the Chinese Navy submarine unit. After 73 years of ups and downs, this unit underwent 8 changes, creating many "firsts" in the history of the construction and development of the Chinese Navy submarine force. In 1951, China's first submarine learning team was established. As one of them, 93 year old Xu Ruitian still remembers the difficulties of starting from scratch. "I have never learned it before. At first, it was difficult. On the one hand, it was theory, and on the other hand, it was operation." The old man still remembers that when Marshal Peng Dehuai came to inspect, he asked everyone, "Are there any difficulties in learning?" The officers and soldiers replied, "Yes, but we can overcome them.". With this insurmountable spirit, the officers and soldiers completed their graduation exams with scores far above the standard after three years of study, becoming the first backbone of the Chinese Navy submarine force. This indomitable pursuit has now become the character of this unit, guiding generations of officers and soldiers to complete a series of "starting from scratch" feathering and rebirth. Among them is Wang Lei. Having experienced the replacement of three models of submarines, he told China News Agency reporters that the old equipment was designed with mechanization, while the new equipment was operated with automation. "This is like upgrading from 'manual' to 'automatic', which is a qualitative leap. The upgrading of equipment has put forward higher requirements for submarine officers and soldiers.". Wang Lei also said, "It's not that automation is easier, it actually brings greater pressure." With continuous equipment upgrades and weapon updates, submarine soldiers need to enhance their ability to master new equipment, improve their personal knowledge system, and make preparations more detailed. "We are not afraid of sailing far, but we need to be prepared for it." With the support of new equipment, the distant ocean is no longer as distant for the Chinese Navy's submarine troops. Since 2012, the Chinese Navy has placed greater emphasis on building its deep-sea capabilities. Since then, the officers and soldiers of the submarine unit have accelerated their pace towards deep blue, and it has become normal to carry out training and other tasks in the ocean. "When we first set sail, we couldn't imagine going that far." Chen Zilong, from a certain crew of the unit, told reporters that with the change of weapons and equipment and the development of military reform, the offshore training of each crew is increasing year by year, and the practical level of exercises and training is also constantly increasing. In the first half of this year, Chen Zilong's crew had just completed an offshore training mission. When it comes to this dozens of days of "Dragon Palace Tour", he said that there was nothing impressive, "because there was too much training like this.". Wang Lei, who set sail together, also referred to such a long-distance voyage as "a common occurrence". "Now that we have only sailed for twenty or thirty days, we feel embarrassed to call it" going out ".". Normalized high-intensity offshore training brings about repeated breakthroughs in equipment limits, conquest of farther and deeper waters, and innovative changes in underwater combat methods. "Changing equipment is not only about acquiring new equipment, but the main change is the generation of combat effectiveness." Chen Zilong believes that with new equipment as the foundation, the personal qualities of officers and soldiers, as well as the overall capabilities of the troops, have been significantly improved. Many tactics and training methods that were once unimaginable can now be gradually implemented, "catching up with world-class navies.". (Lai Xin She)