SJT-class ROUV

Lore & Background

The SJT-class ROUV series originated with the HR-01, one of the first indigenously developed ROUVs in China. Work on the HR-01 began in 1982 and was completed in winter 1985, entering service the following year. In 1989, it won 2nd place in the Science and Technology Advance Award of the Chinese Academy of Science. Based on experience gained from HR-01, the three subsequent SJT-class ROUVs were jointly developed with a Canadian company from 1985 through June 1987.

The SJT-class includes several distinct models. The SJT-5 is a 12 kg underwater observation robot with four electric thrusters. The SJT-10 is a light ROUV with a single manipulator, primarily used for underwater work on offshore oil platforms, with secondary applications in salvage and inland waterway structure jobs; it is aluminum-framed and equipped with a digitized depth gauge, compass, sonar, lowlight TV camera, and an onboard computer. The SJT-40 is the most capable member of the class, with a maximum operating depth of 400 meters, two manipulators, and similar sensor and computer equipment. Both SJT-10 and SJT-40 serve civilian and military operators, mainly for underwater maintenance of oil platforms and other structures.

Another member of the SJT class is the JH-01 ROUV, specifically designed for underwater dam inspection and maintenance. Its first customer was the Hai He Hydraulic Works Committee, and its satisfactory performance led to orders from other customers, including the People's Liberation Army Navy, which deployed JH-01 for breakwater inspection and maintenance. The JH-01 weighs 37 kg and has a maximum operating depth of 60 meters.

Reader's Guide

The SJT-class ROUV series represents an early and significant step in China's indigenous development of remotely operated underwater vehicles. Beginning with the HR-01 in the 1980s, the series established a foundation of practical experience that enabled the development of many subsequent ROUVs. The collaboration with a Canadian company from 1985 to 1987 for the three main SJT-class vehicles introduced external expertise while maintaining domestic design leadership under Zhu Jimao. The series spans a wide range of capabilities, from the lightweight 12 kg SJT-5 observation robot to the 400-meter-capable SJT-40 work-class vehicle with dual manipulators. The SJT-class vehicles found applications in both civilian sectors—particularly offshore oil platform maintenance—and military roles, as seen with the PLAN's use of the JH-01 for breakwater inspection. The experience gained from the SJT series directly informed the development of later, more advanced ROUVs, including deep-sea vehicles like the ST-6000 and Dragon Emperor, as well as specialized models such as the HR-02, HR-03, and the heavy engineering ROUV capable of operating to 1,500 meters. The SJT-class thus occupies a foundational role in the lineage of Chinese underwater robotics.

Did You Know?

• The SJT-class general designer Zhu Jimao also served as general designer of the earlier Type 7103 DSRV.
• The HR-01, origin of the SJT-class, won 2nd place in the 1989 Science and Technology Advance Award of the Chinese Academy of Science.
• The JH-01 variant was first ordered by the Hai He Hydraulic Works Committee for dam inspection and later adopted by the PLAN for breakwater maintenance.

From Sea Person to a Family of Machines

The SJT-class story begins with a single ambition: to build a remotely operated underwater vehicle entirely on Chinese soil. Work on the HR-01, whose name translates to "Sea Person Number One," started in 1982 and was finished in the winter of 1985, with the vehicle entering active service the following year. At 2.2 tons and 3.1 meters in length, it was a modest but significant machine, rated for 200 meters and equipped with two lowlight television cameras, a still camera, a single manipulator arm, and four hydraulically driven propulsors. Its success earned it a second-place finish in the Chinese Academy of Sciences' Science and Technology Advance Award in 1989. Crucially, the lessons learned during HR-01's development became the blueprint for what followed: between 1985 and June 1987, three additional SJT-class vehicles were built in partnership with a Canadian company, marking the first international collaboration in the program and setting the stage for the broader family of machines that would carry the SJT name.

A Ladder of Capabilities

One of the most striking features of the SJT family is the sheer range of sizes and roles it encompasses. At the light end sits the SJT-5, a mere 12-kilogram observation robot driven by four electric thrusters, and the SJT-10, a single-manipulator workhorse built around an aluminum frame and outfitted with a digitized depth gauge, compass, sonar, lowlight camera, and onboard computer. The SJT-10 found its primary calling on offshore oil platforms, with salvage and inland-waterway structural work as secondary tasks. Moving up, the SJT-40 doubles the manipulator count and pushes the depth rating to 400 meters, serving both civilian and military operators for platform maintenance. The engineering series extends the ladder further: the Medium engineering ROUV handles 500 meters with five cameras and six lights, the Max electrical variant reaches 1,000 meters while weighing only 0.8 tons, and the Heavy engineering ROUV, at 4.5 tons and rated for 1,500 meters, carries seven cameras, nine lights, and a depth-positioning accuracy of just ±0.05 meters.

Reaching into the Deep and into Niche Roles

Beyond the workhorse engineering vehicles, the SJT lineage spawned machines aimed at the most extreme and specialized underwater tasks. The ST-6000, completed in June 1995, was designed for deep-sea observation to 6,000 meters and demonstrated its capability on 30 September 1995 by descending to 5,200 meters. Its successor, the Dragon Emperor, pushed the ceiling to 10,000 meters—an increase of two-thirds over ST-6000—and serves as an experimental platform for validating subsystems destined for future ultra-deep vehicles. At the opposite extreme, the HR-02 and HR-03 are small vehicles built for confined spaces, with HR-03 adding sample collection and underwater construction to its observation duties. The JH-01, at just 37 kilograms and 60 meters, was purpose-built for dam inspection; its first buyer was the Hai He Hydraulic Works Committee, and its strong performance attracted further orders, including from the People's Liberation Army Navy for breakwater work. The 8H4, a JH-01 derivative, multiplies the depth rating tenfold to 600 meters and adds two manipulators for cutting and welding.

Design Leadership and a Lasting Blueprint

Behind the entire SJT family stands a single figure: Zhu Jimao, a professor at the Institute of Underwater Engineering of Shanghai Jiao Tong University, who served as general designer for the class and had previously held the same role on the earlier Type 7103 DSRV. The program itself was a genuine joint effort between SHJTU's underwater engineering institute and the Shenyang Institute of Automation under the Chinese Academy of Sciences, a partnership that produced everything from the 12-kilogram SJT-5 to the 10,000-meter Dragon Emperor. The SJT series also introduced an international dimension: three early vehicles were co-developed with a Canadian firm between 1985 and mid-1987, a collaboration that helped broaden the engineering base. Perhaps the most telling measure of the class's impact is what came after it. In that sense, the class is less a finished product than a foundational curriculum, a body of hard-won knowledge that continues to shape Chinese underwater robotics well beyond the vehicles it directly produced.