Type 925 Dajiang Class (Submarine Rescue Ship)
The Dajiang-class AS is a large multipurpose, ocean-going support vessel equipped with a large hydraulic deck crane and a helicopter landing deck. All three vessels in the class were built at the Shanghai Shipyard Jiangnan (Kiang-nan) Dock Company. These large multirole submarine support ships can serve both as alongside tenders and salvage/rescue ships. Can carry two salvage/rescue submersibles, handled by a large crane on the foredeck.
The "July 18 Project" is named after project date - July 18, 1967. On that day, the Commission of Science, Technology and Industry for National Defense submitted a plan for the establishment of the Ocean Surveying Fleet to the Central Committee. It is scheduled to be officially approved in June of the following year, codenamed "Seven-eighth Project", aimed at orbiting the Earth, satellites, launch vehicles, spacecraft, etc. Flying spacecraft for measurement, control and recycling.
In 1974, the State Council determined that Jiangnan Shipbuilding became the main factory of the "July 18 Project" and assumed the construction tasks of the Type 3 ship, namely the space survey ship "Yuanwang 1", "Yuanwang 2" and Yuanwang Survey Ship "Xiangyanghong 10" and salvage lifeboats "J302", "J502", "J121".
Thse were the first large-scale integrated ship owned by the Chinese Navy. Its main mission is to implement surface water for intercontinental missiles and warhead wrecks. Salvage and serve as a telemetry mission; perform surface salvage and rescue astronauts on spacecraft; complete hydroacoustic measurement of intercontinental missile landings and perform sonar arrays for surveying ships; implement three-level rescue and deepwater rescue for submarine accidents, and take into account rescuing ships that was damaged in the water.
The Chinese Navy designed the Dajiang class to fill a need for splashdown retrieval in the intercontinental missile testing, deepsea rescue and, in the future, astronaut recovery. Although its primary function was submarine support and rescue, the other functions of the Dajiang could include supporting the submarine-launched ballistic missile test program as a reentry vehicle recovery ship.
The ship is equipped with deep diving rescue boat, 56 ton hydraulic folding arm crane, life saving bell, three pressure reduction holds at a pressure of 25 kg/cm2, two large helicopters with hangar, take off and landing platform and navigational equipment, fast workboats, 1,000 meter deep water anchor, 200 meter deep water large sized positioning anchor and facilities to serve the position pinpointing operation at sea. The design and construction of this ship were the same as those of ocean going surveying ship.
In its submarine rescue capacity, the Dajiang employed a deep-submergence rescue vehicle (DSRV). A DSRV was identified at the Shanghai Shipyard Jiangnan Dock Company in September 1979, and all three Dajiang units have DSRV deck cradles for storing the vehicle. Although no details of the Chinese DSRV were initially available, it appeared to be similar to the DSRV for the US Navy. Equipment of this kind is usually designed for depths beyond 200 meters and indicated China's intention to carry out long-range, deep-water submarine operations.
The first ship started construction in 1975 and was completed in November 1979 for use. In order to reduce the number of ship types and speed up construction, by one report her overall design was basically the same as that of the ocean going surveying ship, though. This design is also used for several other auxiliaries.
During the Chinese ICBM test in the early 1980s, one of the Type 925 Dajiang class was converted as missile instrumentation support ship and temporarily renamed as Yuanwang-3 to support the test, and after the conclusion of the test, the unit was converted back to its original role with the name consequently changed back.
The ocean-going rescue ship "Yongxingdao" of the Navy of the Chinese People's Liberation Army (PLAN) arrived at the waters to the east of the maritime searching area in the Gulf of Thailand at 15:00 on the afternoon of March 14, 2014, according to the special task commanding group of the PLAN for the search and rescue of the contact-losing plane of the Malaysia Airlines.
According to the briefing, the ocean-going rescue ship "Yongxingdao" set sail from a military port in Sanya of south China's Hainan province on the morning of March 12, carrying 48 divers, 25 technicians, 18 sets of deep diving equipment, 30 sets of light diving equipment, a set of underwater robot, 3 sets of sonar and side-scan equipment, and 8 rescue boats of various types as well as such advanced medical devices as respirators, B-type ultrasonography, ECG monitor instrument and defibrillators.
This is the third batch of rescue forces dispatched by the PLAN after those of the guided-missile frigate "Mianyang", the amphibious dock landing ship “Jinggangshan”, the amphibious dock landing ship “Kunlunshan”, the guided missile destroyer "Haikou", and the comprehensive supply ship “Qiandaohu”.
As a large-size ocean-going rescue ship independently researched, developed and designed by China, the ocean-going rescue ship "Yongxingdao" has such features as long duration of cruise, advanced detection equipment and matured rescue technology. It is mainly responsible for diversified tasks, such as offshore and ocean-going rescue, diving support, salvage, foreign-aid damage control and so forth.
J121 Changxing Island
The “J121” is the “Changxing Island” ocean-going rescue boat. It is a Type 925 ocean lifeboat.
“Changxing Island” was started as the third ship of this series in November 1978. It was delivered in May 1982. In October 1982, the “Changxing Island” replaced a generator set to further improve the overall performance of the ship.
The "Changxing Island", which is the third ship of the series of ships, and the two "big brothers" - "J302" and "J506" have been participating in the launch test of China's launch vehicles and communication satellites for a long time.
On November 20, 1984, China’s first Antarctic expedition team set off. The two ships of "Xiangyanghong 10" and "Changxing Island" sailed across the Pacific Ocean, avoiding typhoons, crossing the equator, and the west wind belt. After dozens of days of sailing, they arrived in Ushuaia, Argentina on December 19, 1984. They continued to sail to the destination of Antarctica after three days of replenishment. December 30, 1984 was a day of great significance in the history of the Antarctic study in China. On this day, the Chinese first inserted the five-star red flag into Antarctica. The five-star red flag flutters in the cold wind of the Antarctic, as if to say: "Antarctic! China is here!"
On the 19th of January 1985, the "Changyanghong 10" sailed to the Southern Ocean for inspection. “Changxing Island” continued to stay in the Civil Defense Bay to assist the Antarctic expedition team to establish a station. In the environment of shortage of materials, lack of building materials, and freezing in the cold, the officers and men of Changxing Island built the first scientific research station in China, the Great Wall Station.
The monument of the Chinese Navy standing at the Great Wall Station in the Antarctic is the "Xiangyang Red 10" and "Changxing Island" that were made with the anchor of "Changxing Island" in the Antarctic. It also proved to the world that it was designed and built by the Navy. The ocean-going survey ship and life-saving ship were successful. The "Changxing Island" glory for the country was also awarded the first prize of China's first national scientific and technological progress in 1985.
861 Changxing Island
In 2003, the "Changxing Island" number was changed to "861", which opened a new story. In March 2005, “Changxing Island” participated in the Sino-Russian “Peace Mission-2005” submarine rescue exercise. In 2014 and 2016, “Changxing Island” participated in the escort of the Gulf of Aden twice, with a cumulative flight time of more than 6,000 hours, berthing six national ports, with a range of more than 40,000 nautical miles, equivalent to two rounds around the earth.
The "Changxing Island" ship [hull number 861] of the Navy of the Chinese People's Liberation Army (PLAN) returned to China 30 December 2014 after wrapping up its water supply mission of in Maldives, and berthed at a naval port in Qingdao on the morning of December 30, 2014. A ceremony was held by the North China Sea Fleet of the PLAN at the wharf to welcome the return of the "Changxing Island" ship. Du Jingchen, deputy commander of the PLAN, attended the welcome ceremony and expressed his high respects to those officers and men and their families who had made contributions to the international humanitarian aids.
Late on the night of December 5, after receiving the order of the superior "quick water supply to the Maldives", the Navy "Changxing Island" vessel, which was carrying out escort missions in the Indian Ocean, transferred to the sea and sailed at a high speed. It took only 53 hours to reach the city of Male. Afterwards, the “Changxing Island” ship continued to be anchored outside the port of Male, using fresh water from the ship's desalination plant to supply fresh water 150 tons in batches, which directly reduced the pressure on freshwater supply in Male City and eased the urgent need. The emergency water supply mission lasted 10 days. The Changxing Island ship used its fresh water stored and seawater desalination equipment to provide nearly 800 tons of fresh water to Male City. Dong Zhen, the aid mission commander, said: "The Navy as an international service, especially the growing and growing Chinese navy, should bear more non-war military missions such as humanitarian relief, and have the obligation and ability to help the Maldives tide over the difficulties."
To help the people of Maldives, the “Changxing Island” ship has taken various measures to deliver fresh water to Male. Zhang Chang, the captain of the "Changxing Island" ship, said that after receiving the aid mission, the water supply time of the "Changxing Island" vessel dropped from 5 hours a day to 2 hours a day, controlling domestic water and drinking water, and reducing personnel.
After Maldives turned to China for urgent provision of fresh water, the "Changxing Island" ship set out and arrived at the designated port of Maldives at the top speed, produced fresh water at its peak load and provided fresh water as much as possible, easing the fresh water crisis in Maldives effectively and winning unanimous praise from the public at home and abroad. It is learnt that Yuan Yubo, deputy commander of the PLA Jinan Military Area Command (MAC) and commander of the North China Sea Fleet of the PLAN, Bai Wenqi, deputy political commissar of the PLA Jinan MAC and political commissar of the North China Sea Fleet of the PLAN, and other leaders above the army level attended the welcoming ceremony.
Water may be produced on ships by desalination, reverse osmosis or distillation. A complete desalination process demineralizes seawater. This makes it corrosive, shortening the life of containers and conduits with which it is in contact. Special consideration needs to be given to the quality of such materials, and normal procedures for certification of materials as suitable for potable water use may not be adequate for “aggressive” desalinated water.
Because of the aggressive nature of desalinated water and because this water may be considered bland, flavourless and unacceptable, it is commonly stabilized by the addition of chemicals such as calcium carbonate. Once such treatment has been applied, desalinated waters should be no more aggressive than waters normally encountered in drinking-water supply.
An evaporating plant that distils seawater and supplies water to the potable water system must be of such a design to produce potable water reliably. Distillation uses heat and pressure changes to vaporize seawater, thus liberating it of its dissolved and suspended solids and almost all dissolved gases. High- and low-pressure units connected directly to the potable water lines should have the ability to go to the waste system if the distillate is not fit for use. As water is evaporated at low temperatures (< 80 °C) in low-pressure units, it cannot be guaranteed that the distillate is free from pathogens. According to ISO standards, water that has been produced at temperatures below 80 °C needs to be disinfected before it can be defined as potable.
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