Building of huge dredger underway

China has started building the nation's largest and most advanced dredging vessel of its type to maintain and improve navigable waterways as well as create or maintain land formations.

The manufacturing of some sections of the new vessel, which has yet to be named, has been underway since January at Shanghai Zhenhua Heavy Industries' Qidong Marine Engineering in Jiangsu province.

Research and development work for other sections of the ship, an engineering vessel known as a trailing suction hopper dredger, is also underway at the Marine Design and Research Institute of China in Shanghai, a subsidiary of China State Shipbuilding Corp, according to Fei Long, a senior researcher at the institute who is overseeing the project.

Fei said during a media briefing at the institute on Tuesday that upon its completion, the new ship will become the largest trailing suction hopper dredger in Asia.

Qidong Marine Engineering will build three such ships in the first orders, the researcher added. The first is scheduled to be delivered to China Communications Construction, a State-owned engineering and infrastructure giant, in 2026, and will be used to carry out dredging, land reclamation and sand collection operations along the estuaries of the Yangtze and Pearl rivers, as well as waterways of coastal ports.

A trailing suction hopper dredger uses its trailing drag head, which is comparable to a large vacuum cleaner and is pulled along a seabed or riverbed, to loosen material. It then employs a suction pipe system connected to the drag head to suck substances such as sand, clay, silt and gravel into a hopper.

After the underwater operations, the collected substance will either be dumped somewhere through hatches on the bottom of the vessel, or mixed with water to be loosened or liquefied before being pumped to a desired site.

A trailing suction hopper dredger is commonly used for two kinds of operations: maintaining the depth of a harbor, canal or waterway to ensure smooth maritime traffic, and transporting seabed and riverbed materials for land reclamation, beach nourishment or construction of artificial islands.

"The new ship will be nearly 195 meters long and 38.5 meters wide. It will be able to suck materials from a maximum depth of 120 meters and can contain about 35,000 cubic meters of seabed or riverbed substances," Fei said.

The researcher said the vessel represents China's highest level of design and building capability for dredger ships, adding that it has the most powerful suction pipe system in the country.

"Its user, China Communications Construction, has become a rising player in the international market of dredging businesses, but it still lags behind the four major dredging companies from Europe in terms of large dredging hardware," Fei said.

There have been 10 trailing suction hopper dredgers in the world with a holding capacity of at least 30,000 cu m of sand and clay. The biggest such ship in China was bought from the Netherlands and has a capacity of 21,000 cu m, while the largest domestically built one has a capacity of 20,000 cu m.

So far, Fei's institute — the only developer of trailing suction hopper dredgers in China — has designed more than 40 such machines, making the nation one of the leaders in this specific field.

In May 2017, the Commerce Ministry and the General Administration of Customs published a notice banning the export of large dredgers by any individual or entity unless expressly permitted by the Chinese government.