Workers release the deep-sea submersible Jiaolong at Yap Trench in western Pacific Ocean on May 15, 2016. It was the first diving mission of Jiaolong at the area, and it reached 4,955 meters under the sea. [Photo: Xinhua]

China will start building research vessel Dayang Erhao (Ocean No.2) and a mother ship for manned submersible Jiaolong, both expected to be put into service in March 2019.

The China Ocean Mineral Resources R&D Association on Friday signed contracts with two ship manufacturers to begin construction on the research vessels with plans to finish the projects in about 28 months.

According to the association, the Dayang Erhao will have a displacement of 4,000 tonnes and measure 98 meters long and 17 meters wide.

It will contain more than 400 square meters of laboratory space be equipped with over 70 types of research devices.

Dayang Erhao will be capable of conducting scientific missions, including seabed, water and atmospheric research, deep-sea extreme environment detection, as well as observations on marine geology and ecology.

The new mother ship, with a displacement of around 4,000 tonnes, is designed to provide support and maintenance to Jiaolong's deep sea diving tasks.

At 90.2 meters long and 16.8 meters wide, the mother ship will have different types of laboratories filling more than 300 square meters.

The mother ship's research system will be able to complete exploration tasks for Jiaolong's diving activities as well as process and conduct on-site analysis of data and samples.