Type 635 hydrographic survey ship

{{short description|Chinese class of naval diving support vessel}}

{{Infobox ship career

|Hide header=

|Ship country= PRC

|Ship flag= {{Shipboxflag|China|naval}}

|Ship name=

|Ship namesake=

|Ship ordered=

|Ship awarded=

|Ship builder=

|Ship original cost=

|Ship yard number=

|Ship way number=

|Ship laid down=

|Ship launched=

|Ship sponsor=

|Ship christened=

|Ship completed=

|Ship acquired=

|Ship commissioned=

|Ship decommissioned=

|Ship maiden voyage=

|Ship in service=

|Ship out of service=

|Ship renamed=

|Ship reclassified=

|Ship refit=

|Ship struck=

|Ship reinstated=

|Ship homeport=

|Ship identification=

|Ship nickname=

|Ship honours=

|Ship captured=

|Ship fate=

|Ship status=Active

|Ship notes=

|Ship badge=

}}

{{Infobox ship characteristics

|Hide header=

|Header caption=

|Ship class=Yanlai class

|Ship type=Hydrographic survey ship

|Ship tonnage=

|Ship displacement=

|Ship length=

|Ship beam=

|Ship height=

|Ship draught=

|Ship draft=

|Ship depth=

|Ship hold depth=

|Ship decks=

|Ship deck clearance=

|Ship power=

|Ship propulsion=Marine Diesel

|Ship speed=

|Ship range=

|Ship endurance=

|Ship boats=

|Ship troops=

|Ship complement=

|Ship time to activate=

|Ship sensors=Navigation radar

|Ship EW=None

|Ship armament=

|Ship armour= None

|Ship aircraft= None

|Ship aircraft facilities=None

|Ship notes=

}}

Type 635 hydrographic survey ship is a series of hydrographic survey ships developed by China for its People's Liberation Army Navy (PLAN). More successful than Type 625 of the same era, Type 635 still remains active in PLAN after half a century of service, even after its successor Type 636 has entered service. Type 635 series in PLAN service are designated by a combination of two Chinese characters followed by three-digit number. The second Chinese character is Ce (测), meaning survey in Chinese, because these ships are classified as survey ship. The first Chinese character denotes which fleet the ship is service with, with East (Dong, 东) for East Sea Fleet, North (Bei, 北) for North Sea Fleet, and South (Nan, 南) for South Sea Fleet. However, pennant numbers may have changed due to the change of Chinese naval ships naming convention.

Type 635A/B/C

Type 635 A/B/C series with NATO reporting name Yanlai (延来) class{{cite web| url=https://news.usni.org/2015/08/07/document-office-of-naval-intelligence-chinese-military-and-coast-guard-ship-identification-guide | title=PLANS recognition guide 2015| date=August 7, 2015}} is the first batch of the Type 635 series. These ships are sometimes collectively known as Type 635I, because the difference between these models are relatively minor in comparison to the second batch. These ships differ from second batch in that the deck at the stern is circular shaped and they are purely for surveying missions. Construction of the first ship begun in 1970 and some modification was made to the second ship, which was designated as Type 635B, and the first ship was subsequently designated as Type 635A. In 1976, based on the experienced gained from deployment, PLAN required further upgrade of Type 635B and these ships are designated as Type 635C. Design was completed in Jun 1977 and construction for both ships begun simultaneously in October of the same year, and they entered service respectively in 1982 and 1983. Type 635C actually developed later than Type 635II, and they are built by Jiangxi Ruichang Jiangzhou Shipyard (江西瑞昌江州造船厂), a division of [http://www.jzshipyard.com.cn/ Jiangzhou Union Shipbuilding Co., Ltd. (江西江州联合造船有限责任公司)] Specification:{{cite web| url=http://www.haijun360.com/news/DCCCLC/2011/1124/1111241308CH4FCD39A7H5AI852I8A.html | title=Type 635| access-date=27 May 2014 }}

Length (m): 74.8
Length between perpendiculars (m): 68.6
Beam: 10
Depth (m): 4.7
Draft (m): 3.5
Displacement (t): 1216
Main propulsion: two diesel engine @ 1320 kW (1800 hp) each
Max wind scale allowed for sailing: 10
Range (nm): 4000

Type 635II

Type 635II is the development of Type 635A/B, and differs from its predecessor in that in addition to hydrographic survey missions, Type 635II is also capable of carrying out ASW and mine laying missions. To carry out these combat missions, additional armament was added. The most obvious visual external difference between Type 635A/B/C (Type 635I) and Type 635 II is that the deck at the stern of Type 635II is in rectangular shape, instead of the circular shape of that of Type 635I. Construction begun in 1970, but due to political turmoil in China, namely, Cultural Revolution, it was not half a decade later was the ship finally delivered. Specification:

Length (m): 81.2
Length between perpendiculars (m): 76
Beam: 9
Depth (m): 4.4
Draft (m): 3.54
Displacement (t): 1245
Main propulsion: two diesel engine @ 1320 kW (1800 hp) each
Max wind scale allowed for sailing: 10
Max speed (kt): > 17
Range (nm): 4200
Endurance (day): 30
Armament: 2 twin 37 mm gun, 2 twin 25 mm gun, 2 depth charge mortar, 2 mine rails