Type 646 hydrographic survey ship with NATO reporting name Kanyang (勘洋, meaning Surveying Oceans) class^[1][2][3][4] is a type of survey vessel currently in service with the People's Liberation Army Navy (PLAN).

Type 646 Kanyang class survey ship is designed by the 4th Directorate of the 708th Institute of China State Shipbuilding Corporation (CSSC), which is also more commonly known as China Shipbuilding and Oceanic Engineering Design Academy (中国船舶及海洋工程设计研究) Archived 2019-07-06 at the Wayback Machine nowadays. Construction of both ships begun simultaneously in December 1978 and both were launched in 1982, and both entered service with PLAN South Sea Fleet in 1978. In comparison to earlier shps converted from fishing and cargo vessels, these purposely designed ships carried more equipment and greatly improved efficiency. These ships are named as Nan-Ce (南测, meaning South Survey), followed by a three digit number. South means South Sea Fleet and Survey means that these ships are survey vessels. Specification:^[5]

• Length (m): 60
• Displacement (t): 676
• Speed (kt): 15.51
• Survey speed (kt): 3 – 4

v t e Active ships of the People's Liberation Army Navy
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Hospital ships (AH) Hospital ships (AH) Type 919 Anshen class Type 920 Anwei class Medical evacuation ships (AHP) Zhuanghe Ambulance transports (APH) Qiongsha class Ambulance craftd (YH) Ankang class Hydrographic survey ships (AGS) Type 55 Shantou class Type 068/069 (Yuch'in class) Type 635 A/B/C & Type 635II Yanlai class Type 636A Shupang class Type 639A Shupang class Type 646 Kanyang class Type 8101 Type 8105/Type 8154/Type 792 FT-14 AIT class Yanjiu class Icebreakers (AGB) Type 272 Museum ships PLANS Heroic Gunboat in the Toumenshan Naval Battle PLANS Liberation Minquan-class gunboat (replica) Project 183 P-6-class torpedo boat Type 021 missile boat Type 024 missile boat Type 031 ballistic submarine (SSB) Type 033 submarine (SS) Type 051 destroyer (DDG) Type 053K frigate (FFG) Type 091 submarine (SSN) Type 6607 destroyer (DDG) Oceanographic research ships (AGOR) Type 639A Shupang class Type 645 Zhang Jian Oceanographic surveillance ships (AGOS) Ruili No. 10 Type 927 Dongjian class 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Chinese sailless submarine Torpedo trials craft Torpedo retrievers (TR/TWR) Dachou class AGT/TR/TWR Type 803 Type 917 Damen class AGT/TR/TWR Torpedo trials ships (YTT) Type 906 Xiang Yang Hong 9 class AGE/YTT Type 907A Tracking ship (AGM) Type 830 ATR/AGM Yuanwang class ARIS/AGM Training ships (AX) Training ship (AX) Daguan APB)/APT/AXT Type 0891A Dashi class Type 679 Daxing class Type 680 Dadu class Yanxi class ATLS/AX Training ship, sail (AXS) Type 2630 Onshore stationary training facilities Type 033 (Romeo class) Type 051/051Z (Luda class) Type 053H1Q (Jianghu-IV class) Type 6607 (Anshan class) Tugs (AT) Harbor tug (YT) Beituo 617 class Beituo 699 class Beituo 702 class Beituo 715 class Large harbor tug (YTB) Ducha class Duda class Duhast class Dupo class Rescue Tug (ATR) Bei-Tuo 739 class Datuo class ARS/ATR Dong-Tuo 835 class Haixiu 121 class Daozha class Type 830 AGM/ATR Sea-going Tug (ATA) Type 802 Gromovoy class Type 837 Hujiu class Type 852 Roslavl class Tugs of unknown class/type Bei-Tuo 153, 651, 704, 728, Dong-Tuo 845, 861, Nan-Tuo 142, 163, 168, 176, 187, 188 UAV mothershps (ATLS) Fighting Shark No.1 Yanxi class AGM/AVM/ATLS Unmanned surface vehicles (USV) CASIC USVs Chinese Sea Hunter Sky Journey 1 HUST USVs JARI USV JUST USV Ostar USVs PWT USV Shanghai University USV Type 80 demolition boat VVLAI USV WSST USVs Yunzhou USVs Unmanned underwater vehicles (UUV) Autonomous underwater vehicle (AUV) CR series Explorer series HSU-001 Intelligent Water class JUST AUVs Micro Dragon Series Orange Shark series Ostar AUVs Poseidon series Robosea AUVs Sea Clever Sea Whale series Submerged Dragon series THLMT AUVs Wukong WZODA XTDT Benthic landers CAS series Rainbowfish series Bottom crawlers Aquadrobotman series CSSC series Deepinfar series JUST series Robosea series SBSS series Sea Crab Sea Star THLMT unmanned vehicles#Underwater series VVLAI series Hybrid UUVs (Autonomous remotely -operated vehicles, ARVs) 7B8 Arctic series Hadal Hadal 1 Rainbowfish ARV Remotely operated underwater vehicle (ROUV) 8A4 8H4 Aquarobotman ROUV Deepinfar ROUVs Discovery Dragon Emperor Dragon Pearl Goldfish series JH-01 (Jiao-Hai 01) JTD-01 Deep Eel I JTML-02 JTMP series JTR series JUST ROUVs Max ROV Oceanxer ROUVs Ostar ROUVs PWT ROUV RECON-IV ROUV Robosea ROUVs SBSS ROUVs Sea Dragon series Sea Person (Hai-Ren/HR) series Sea Pole Sea Star 6000 Sea Submergence series SJT series ST-6000 THLMT ROUVs VVLAI ROUVs Walrus 1500 Underwater gliders Flying Wing Petrel series Sea Soar series Deepinfar Sea Wing series THLMT series Wave gliders CSSC series Hydrovo series Ostar series THLMT Black Pearl Weapon trials ships (AVM/AGM) Type 909 Wuhu-B class Type 909A Dahua class Type 910 Dahua-II class
* = Under construction or procurement, CG= Classified as guided missile cruiser by NATO, FF= Classified as light frigate by PLAN