Type 625B Class (Hai Yang Class) Chinese Oceanographic Research Vessel

The Type 625B Class (Hai Yang Class) Chinese Oceanographic Research Vessel is a series of oceanographic research ship developed by China for its People's Liberation Army Navy (PLAN). The series consisted of three models, A, B & C, but A & B are usually grouped together as one because C model differs from Models A & B on much greater scale. Type 625A/B is the first member of the Type 625 series. Requirement of Type 625 was issued in the late 1970s, and a total of four units were planned. Construction of the first unit begun in the early 1970s, and others followed. Based on the experience of deployment, the fourth unit has some improvement, and the difference is large enough to have a different designation as Type 625B. Subsequently, the original Type 25 was re-designated as Type 625A, and the term Type 625 is used to denote all models in the series. These ships are named from Ocean (Haiyang, 海洋) 1 through Ocean 4 respectively. The main difference between the fourth unit and the first three is that the fourth unit is larger and able to operate for longer period of time in extended missions. The fuel tank is increased in size, and sea water distillation and oil and water processing systems were upgraded. A bow thruster and new radars were added. Ocean 4 carries many western scientific research instruments such as that manufactured by US companies including Raytheon, and this was one of the first deals for these US companies to have successfully marketed their products in China.