Farmer from East China’s Anhui Province builds submarine capable of 8-meter dives

A 60-year-old farmer from Maanshan, East China’s Anhui Province, has successfully built a submarine on his own, the China Central Television (CCTV) reported. The five-ton homemade vessel, named "Big Black Fish," is capable of diving to a depth of eight meters.
The farmer, named Zhang Shengwu, has been passionately devoted to invention since childhood, habitually engaging in small creations.

Over 20 years ago, Zhang built a sand dock in his hometown, spending his days watching cargo ships come and go.  

In 2014, Zhang watched a television program featuring submarine construction, which gave him an idea to pursue. "Having spent years near water, I'd seen vessels of steel and wood – but never one capable of descending beneath the waves,” he said.  

“If others can do it, so can I," said Zhang.

Though his family didn’t support him, it didn’t dampen his dream of building a submarine. He began conceptualizing the submarine’s structure in his mind. 

As a seasoned carpenter, he possesses expertise in structural design, complemented by first-hand maritime work experience understanding propulsion systems, the state broadcaster CCTV News said. 

“Once I calculated material requirements, the timeline became clear," Zhang noted.

With the blueprints mapped out in his mind, Zhang spent 5,000 yuan ($699) on steel plates, batteries, engines, and other materials, and started building the submarine. After six months of effort, his first submarine was completed.

Measuring six meters long, 1.2 meters high, and weighing two tons, this submarine earned him a national utility model patent, starting his inventive journey, according to the report.

By 2016, he had developed a surface vessel, winning another utility model patent certificate, CCTV News reported

Zhang didn’t stop there. He invested over 40,000 yuan to build his second upgraded submarine. The new vessel increased in length to seven meters and height to 1.8 meters, featuring a two-person cockpit.

To enhance stability, he poured approximately two tons of concrete into the hull base and installed dual ballast tanks fore and aft. For superior watertight integrity, Zhang welded all joints tightly and made the inlet and outlet circular.

Weighing five tons with seven tons of displacement capacity, the submarine achieves an eight-meter diving depth and a minimum speed of four knots. 

Zhang expressed profound satisfaction, "A single small battery powers an electric motor propelling such substantial craft underwater. It remains completely watertight during 30-minute submersion cycles and possesses reverse maneuverability."  

Regarding future endeavors, Zhang plans to construct larger submarines while helping enhance national defense awareness among youth.