Type 814 Dadie Class "Xiangyanghong 28" geodetic intelligence ship
The 814A near-China sea reconnaissance ship (also known as a geodetic intelligence gathering ship ) was a heavy-duty patrol ship built by the Chinese People's Liberation Army Navy in the 1980s. It was not armed, but the tonnage reached the level of frigates and patrol ships . It belongs to the special mission ship, and can also be used as a task of protecting the fishery. There is only one ship of the North Sea Fleet of the "Northern Tuning 900". It used the name of the North 841, V841, Xiangyanghong No. 28. Following its recent modernisation refit, the ship was renamed BEIDIAO 900. The ship is also known as the Dadie class by Western intelligence.
The Dadie class, of which one was only built, is used by the PLAN for electronic intelligence. The 814A-type near-sea reconnaissance ship, is the only one of its kind. The ship entered in service with the Navy North Sea Fleet Reconnaissance Brigade, which used the ship number: V841-Northern 841 and Xiangyanghong 28. The ship is made of steel, long first floor, double paddle, double rudder, and medium-speed diesel engine driven by the rear-wheel type engine. The first column is leaning forward and has a ball nose.
In 1979, the Naval Equipment Technology Department proposed to track the mid-seas, monitor enemy activities, collect maritime intelligence, and urgently need to build four near-sea reconnaissance vessels, and proposed to refit the 635C medium-sized hydrographic survey vessel. The design of the 708 Institute was reviewed and it was considered that the requirements for the use of the troops could not be met.
In view of the 812 electronic surveillance ship trial-type failure, it was decided to concentrate on the development of the 814A-type near sea surveillance ship. On March 25, 1980, the Naval Equipment Technology Department agreed to redesign the near-sea reconnaissance ship with a displacement of 1,500 tons. The 708 Institute completed the design of the entire 1,500-ton program on June 30, 1980. During the review, in view of the large changes in the requirements of the meeting and the original task book, 708 proposed to increase the displacement from 1,500 tons to 1,800 tons. After the discussion, the proposal was accepted and the tactical technical task book was re-negotiated. The modification plan and technical design were completed in the 708 Institute in February and August 1982; the construction design was completed in August 1983. A total of four hulls were originally planned, but only one actually built. Wuchang Shipyard officially started construction on December 22, 1983, named Xiangyanghong No. 28, launched on June 12, 1986, completed in October of the same year, and conducted a sea trial in Qingdao on October 29.
The special equipment offshore test was carried out from February to May 1987. Under the direct command of the North Sea Fleet, more than 170 people from 20 units including Haisi Intelligence Department and Haizhuang Electronics Department participated in the test, using a three-dimensional test of close cooperation between land, sea and air and underwater. In the test, guided missile destroyers, anti-submarine escort boats and 33 submarines, H-5 and Y-5 aircraft were used; on the shore, there were 403-type sea-alert radars and 63, 64-type ultrashort-wave radio stations. The test proved that the four major reconnaissance systems, such as optical, acoustic, radar and radio communication, are on board.
There are four major systems for reconnaissance: optical reconnaissance system, acoustic reconnaissance system, radar reconnaissance system and radio communication reconnaissance system, and equipped with advanced meteorological satellite receiving system, satellite navigation combined system and complete complete communication equipment.
The main structure of the ship is steel, long first floor, double propeller, double rudder, rear-wheel type medium-speed diesel engine drive boat, the first column forward, with a ball nose. The main parameters are 94.33 meters long; the design waterline is 86.0 meters long; the model width is 11.6 meters; the model depth is 5.7 meters; the design draft is 3.64 meters, the designed displacement is 1861 tons; the full load draft is 4.04 meters, and the full load displacement is 2,198 tons. The weapons are mainly machine guns. Some external weapons can be added.
The maximum speed of the main engine is 20.03 knots at maximum power and 19.54 knots at rated power. At a cruising speed of 18 knots, the endurance is 4000 nautical miles and the self-sustaining power is 45 days and nights. The main engine is equipped with two 6E390 medium speed diesel engines with rated power of 2646 kW (3600 hp) and a speed of 450 rpm. The maximum power is 2940 kW (4000 hp) and the speed is 466 rpm. There are four major systems for reconnaissance: optical reconnaissance system, acoustic reconnaissance system, radar reconnaissance system and radio communication reconnaissance system, and equipped with advanced meteorological satellite receiving system, satellite navigation combined system and complete complete communication equipment.
All equipment on board is equipped with domestic equipment in accordance with the requirements of the Navy's Department of Technology. Due to the need for acoustic reconnaissance, the ship was equipped with an oversized nose and the resistance dropped by 1-2%. Considering that the ship's independent execution of the mission, the activity area is vast and working in the harsh sea conditions, the stability of the ship can resist the 12-level wind. Vibration is the most common problem of this type of medium-speed ship. The 812 reconnaissance ship was scrapped because of severe vibration. Therefore, the 814 ship took lessons from the 812 ship and took special measures. The ship is equipped with a large number of reconnaissance equipment, and the electromagnetic compatibility problem is very prominent. It has absorbed the successful experience of the aerospace survey ship, and the electromagnetic compatibility has been satisfactorily solved.
The North Diversion 900 ship was commissioned by the Beihai Fleet Reconnaissance Ship Brigade in 1986, and its home port is Jiaonan, Shandong. It is still in service. When the ship was commissioned in 1986, it was named Xiangyanghong 28, and it has been named V841 and North Diversion 841 .
According to public information, the ship has adopted domestic equipment in accordance with the requirements of the Navy, equipped with four types of reconnaissance systems such as optics, acoustics, radar and radio communications, and is equipped with an advanced meteorological satellite receiving system and a satellite navigation integrated system. In the analysis of foreign forces, the 814A reconnaissance ship mainly performs tactical reconnaissance tasks, such as acquiring electromagnetic information of opposing ships and coastal radar systems, detecting and tracking underwater targets such as submarines, collecting relevant acoustic information, and analyzing the geographical environment of the sea floor. For detection, it also has certain strategic reconnaissance capabilities such as signal reconnaissance. The construction of the 814A reconnaissance ship indicates that China has initially possessed the ability to build comprehensive reconnaissance ships. In particular, by solving a series of technical problems such as electromagnetic compatibility and the coordination of reconnaissance systems, China will build a larger, more advanced, and more comprehensive capacity for China. The reconnaissance ship has accumulated experience and laid the foundation.
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