China tests submarine cable cutter at 3,500-metre depth

A Chinese deep-sea mission has successfully tested an advanced device capable of cutting through underwater structures such as submarine cable at a depth of thousands of metres. The “Haiyang Dizhi 2” research vessel completed its first deep-sea scientific mission of 2026 on Saturday, according to the Ministry of Natural Resources. The expedition included a cutting test of a deep-sea electro-hydrostatic actuator at a depth of 3,500 metres (11,483 feet), using technology that has drawn attention for its potential military use. “The sea trial has bridged the ‘last mile’ from deep-sea equipment development to engineering application,” the official China Science Daily reported on Saturday, suggesting the equipment was poised for actual deployment. An electro-hydrostatic actuator, or EHA, integrates the hydraulic system, electric motor and control unit into a single compact device, eliminating the external oil piping typical of conventional systems. The EHA represents a cutting-edge advance in power transmission technology, demanding high performance from motors, controls and structural design while delivering greater energy efficiency than older hydraulic systems. The same technology is already used on commercial airliners to drive flight surfaces such as lifts. The device tested in this expedition has been further equipped with deep-sea pressure compensation and corrosion resistance to perform precise mechanical tasks under extreme subsea pressure. The EHA was one of the deep-sea equipment initiatives opened for applications in 2023 by Zhejiang University, which took part in the expedition. According to a September 10 report from the university’s Ocean College: “The system packs the pump, valve, cylinder and controls into a single unit. It removes the need for external hydraulic lines, making the equipment more reliable, more energy efficient and cleaner.” “The technology is under trial for cutting subsea cables and operating deep-sea grabs, opening a new path for powering underwater work,” the report added. Documents posted on Zhejiang University’s website specified the project’s requirements, including external pressure tolerance of more than 35 megapascals, drive power of at least 1.0 kilowatt, a working stroke of at least 100mm (3.9 inches) and output force of more than 50 kilonewtons. The documents also stipulated that at least 85 per cent of the materials and parts be made domestically. The device was successfully developed as early as September last year, when a team led by Mei Deqing and Chen Zheng, both of Zhejiang University, won a gold medal at the 2nd Brics Inventions Exhibition with their project “Sustainable Subsea Electro-Hydrostatic Actuator with Compact Design”. The actuator is expected to play a role in the construction and repair of deep-sea oil and gas pipelines. Other projects university submitted in the same batch included battery packs and thrusters for the Jiaolong-crewed submersible, deep-sea welding systems, rare earth exploration tools and deep-sea BeiDou satellite communication and positioning products. In 2022, during the repair of an offshore pipeline, an imported cutting saw took more than five hours just to make a single cut on an 18-inch (45.7cm) damaged pipe section, relying on repair tools whose market has long been dominated by foreign suppliers. By 2023, Chinese crews were equipped with a domestically produced deep-water cutting saw operated by a remotely operated vehicle, capable of working at depths of up to 2,000 metres and handling pipes from 6-38 inches in diameter. During one pipeline recovery project, the domestic saw sliced through an eight-inch pipe in just 20 minutes. The newly publicised equipment extends the operational depth envelope to 3,500 metres, opening potential applications in severing subsea structures and clearing underwater obstacles. The recent expedition was organised by the Guangzhou Marine Geological Survey in collaboration with 16 institutions, including Ocean University of China, Dalian Maritime University, Shanghai Jiao Tong University, Zhejiang University and the Second Institute of Oceanography under the Ministry of Natural Resources. A hundred scientific personnel aboard the Haiyang Dizhi 2 spent 30 days at sea, carrying out more than 10 research tasks across four major categories, though the vessel’s exact route and test locations have not been disclosed. The Haiyang Dizhi 2 entered service with the Guangzhou Marine Geological Survey under the China Geological Survey in December 2022 after undergoing extensive refit and modernisation. The 85-metre vessel, with a full-load displacement of 7,224 tonnes, boasts a range of 12,000 nautical miles. It is optimised for independent geological sampling and serves as a vital support platform for deep-sea drilling, equipped to handle submarine cable laying and deep-water salvage. During the same mission, a remotely operated vehicle called the “Haima” recovered year-old seabed instruments and gathered a wealth of samples and data. The mission also validated a 10,000-metre seawater sampling winch and tested neutrino detection gear at a depth of 4,000 metres.

China tests submarine cable cutter at 3,500-metre depth

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}Trial described as bridging ‘last mile’ from deep-sea equipment development to engineering application, suggesting deployment is coming next

Trial described as bridging ‘last mile’ from deep-sea equipment development to engineering application, suggesting deployment is coming next