Chinese Farmer Builds Functional Five-Ton Submarine

A 60-year-old farmer from China has demonstrated extraordinary engineering prowess by building a functional five-ton submarine. Zhang Shengwu, who has a background in carpentry, welding, and shipbuilding, embarked on this ambitious project in 2014 after being inspired by a television program featuring a homemade submarine. Despite warnings from his family about the risks and costs, Shengwu persevered, investing his own funds and time.

The latest iteration of his creation, dubbed “Big Black Fish,” successfully completed a test dive in early July 2025, reaching a depth of eight meters. This achievement marks a significant milestone in Shengwu’s decade-long endeavor to master submarine construction as a personal hobby.

Building the First Prototype

Shengwu’s initial foray into submarine building involved an investment of approximately 642 euros (5,000 yuan) for materials including steel plates, a motor, and a battery. Within six months, he had constructed his first prototype, a six-meter-long, 1.2-meter-high submarine weighing two tons. While this early model suffered from a leak, its design was recognized with a patent by the Chinese state, validating its technical merit. Following this, Shengwu also built a surface boat, which also received a patent.

Developing the “Big Black Fish”

Undeterred by the leaks in his first attempt, Shengwu dedicated himself to developing a more advanced vessel. He invested over 5,000 euros (40,000 yuan) into creating the second generation of his submarine, which would become the “Big Black Fish.” This advanced model features a seven-meter-long hull with a height of 1.8 meters, providing space for two occupants.

To enhance stability, Shengwu incorporated approximately two tons of concrete into the hull as ballast and installed two ballast tanks at the bow and stern. These tanks are used to control buoyancy, filling with water for submersion and emptying for ascent. Addressing the leakage issues of his previous design, he meticulously welded every joint and fitted circular hatches.

Performance and Capabilities

The “Big Black Fish” is reported to be capable of reaching speeds of up to four knots. Shengwu expressed pride in its performance, noting that a modest battery and motor can propel the substantial structure underwater. He stated that the submarine can remain submerged for up to half an hour without any water ingress and can even maneuver in reverse.

Context of Homegrown Innovation in China

Shengwu’s achievement, while remarkable, is not entirely unique in China. The country has seen a number of instances of individuals undertaking ambitious DIY engineering projects. In 2009, Li Yuming reportedly built five homemade submarines. In 2014, a former prison official named Zhang Junlin developed a tourist submarine, which he tested in the South China Sea. In 2015, a villager in Shaanxi reportedly incurred significant debt to construct a 9.2-meter submarine.

Government Support for Rural Talent

This trend of rural innovation is partly supported by government initiatives. In 2020, China set a goal to cultivate one million “innovation leaders” and 15 million entrepreneurs in rural areas by 2025. In provinces like Anhui, where both Shengwu and Zhang Junlin hail from, individuals engaging in such stable entrepreneurial activities may be eligible for an initial grant of 5,000 yuan. Shengwu exemplifies this profile – an individual without formal higher education, yet possessing the persistence and hands-on skills to execute complex technological projects. While not on the scale of the Chinese military’s submarine capabilities, his creations are functional, demonstrating a capacity to submerge, navigate, and surface. Shengwu is already planning his third submarine, aiming for a larger design with increased autonomy.

Key facts
| Feature | Detail |
|—|—|
| Builder | Zhang Shengwu |
| Age | 60 |
| Occupation | Farmer |
| Project | Homemade Submarine (“Big Black Fish”) |
| Weight | 5 tons |
| Diving Depth | 8 meters |
| Occupancy | 2 people |
| Estimated Cost (Big Black Fish) | ~€5,000+ (40,000 yuan) |

Source: Este agricultor chino de 60 años tiene un hobby inusual: construir submarinos. El último pesa cinco toneladas y funciona – Xataka, https://www.xataka.com/movilidad/este-agricultor-chino-60-anos-tiene-hobby-inusual-construir-submarinos-ultimo-pesa-cinco-toneladas-funciona

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