Chinese Researchers Build Saw That Can Cut Cables at 4,000M Depths

A handful of advanced nations have the capability to cut subsea cables in ultradeep water, but the technology is usually a closely-held state secret. In a research paper published late last month, a Chinese scientist detailed a unique submersible diamond saw that can be used for “marine resource development” purposes at extreme depth and pressure.

“Enhancing marine resource development capabilities, advancing the blue economy and building China into a maritime powerhouse constitute critical components of realizing the Chinese dream,” explained researcher Hu Haolong of the China Ship Scientific Research Centre (CSSRC), writing in the peer-reviewed journal Mechanical Engineer. 

The device in question is a robotic arm-mounted circular saw, designed to operate in water depths of up to 4,000 meters – a typical depth for the Pacific abyssal plain. Dozens of subsea cables crisscross the Pacific, linking data customers in Asia’s thriving business hubs with markets in the West. These cables – and others just like them around the world – handle about 95 percent of all international data traffic, including phone calls, internet data and private network data. 

At water depths greater than about 2,000 meters, the cable lay industry does not typically bury subsea data cables, and avoids the cost and hassle of trenching by simply placing the cables on the seabed instead. These fiber-optic lines are thin and unobtrusive, just 20-60 mm in diameter, but they are comparatively strong, capable of withstanding a strain of up to 20-70 tonnes before breaking. 

Hu’s robotic device is titanium-clad to withstand the extreme pressures of 4,000 meters of depth, which happens to be the same depth range where unprotected subsea cables are found. With a six-inch diamond blade, the saw can cut through steel-armored cables of up to 60mm in lab testing (image at top). 

CSSRC is one of the research arms of state-owned giant CSSC,