China's new manned submersible, which is capable of reaching a depth of 4,500 meters, conducted a whole-process water tank experiment by simulating real open-sea dives on Sunday in the city of Wuxi, east China's Jiangsu Province. 

The whole-process water tank experiment is a crucial step for a submersible to go through sea trials, in which the condition is more severe as water pressure increases drastically. The first water tank experiment is expected to last six hours, and more will be undertaken in the following two months.

The submersible, independently developed by China with its name undecided yet, has completed over 20 individual tests in over 15 dives in an experimental water tank since April 13. 

China's new homegrown manned submersible. /CGTN Photo

So how is this new manned submersible different from China’s first manned submersible, Jiaolong, whose deepest dive record of 7,062 meters was the highest among all known manned submersibles?

The new submersible is very similar to Jiaolong in terms of appearance, but it has achieved localization as about 95 percent of its core parts were domestically manufactured, whereas Jiaolong has many of its parts imported. 

An expert explains the difference with Jiaolong. /CCTV Photo

In addition, it incorporates some new features, such as two more observation windows, and the replacement of silver-zinc batteries by lithium batteries so they can be reused 10 times more than before, from 50 to 500. 

At the depth of 4,500 meters, the submersible is capable of covering almost all major sea areas in China and waters that International Seabed Authority (ISA) permitted for marine mining. 

Checking the submersible before its first water tank experiment. /CCTV Photo

"Two factors will possibly influence the experiment, namely the weather and the performance of the submersible,” said Hu Zhen, the chief designer of the manned submersible. 

“We have to take possible thunderstorm into account as it is summer now. As for the performance of the submersible, we have to keep the vehicle in its best technological shape, so that it can simulate all real protracted dives in the open sea." 

The Ti80 manned sphere, the submersible's most important core part, is big enough for three people. /CCTV Photo

The chief designer also introduced the steps of the whole-process water tank experiment. 

"The first step is that workers go into the submersible to conduct preparation. The second step is to launch the submersible into water and bring it to deeper levels. The third step is to carry out underwater operations when the submersible sit on sea bottom," he explains. 

Hu said that the submersible will go through sea trials in July, and is expected to have two female drivers inboard.