East Vietnam Sea survey team – P2: ‘Copying’ seabed and ‘pasting’ it on screen

After dropping a robotic shark into the ocean to automatically record sea data, the ship 884 began slowly dragging the equipment at the rate of four nautical miles an hour.

All data collected by the shark was sent to computers in the cabins of technicians.

On the computer screens data was coded in colors. Other screens displayed objects lying on the seabed.

First Lieutenant Nguyen Van Dai explained, “Different colors represent different depths of the seabed.

“Red strips show the locations where the sea is shallow.

“Yellow strips mean it is deeper, while green and violet colors represent the deepest depths.”

The exact depth of the sea will be identified later and analyzed with certain special equipment, he added.

For some data like salinity levels, properties of seabed terrain, sea currents and hydrometeorology, the ship has to repeatedly “plough” through areas to collect samples at different times with different natural conditions.

All the data is decoded and mapped onto three-dimensional nautical charts that meet international standards.

Master and Lieutenant Colonel Nguyen Phuc Hong, vice head of the team 695 under the 6th naval squad, said the naval squad in charge of maritime studies has been equipped with state-of-the-art facilities.

Four SSS systems are used for analysis of the seabed structures in maritime archaeology.

The facilities can be used for military purposes for detecting bombs and mines at sea and mastering the structure of the seabed for the possible establishment of an underwater military base.

The sea surrounding the Pirates’ Archipelago in the west of Vietnam bordering Cambodia is shallow and researchers of the 6th naval squad have to access by motorboat.

Water samples are collected at different depths to identify levels of pH, gas and salinity.

This data is important for the navy and can determine the success or otherwise of launching a torpedo or missile from a submarine.

The maritime sound waves are not homogeneous but change at varied sites in different natural conditions.

This means that communications in submarines change at different depths and in different natural conditions that naval researchers must master as well as possible.

This data and prevailing natural condition must be available on computer screens for submarine officers.

“In general, the speed of sound under water is 1,400-1,600 meters per second,” First Lieutenant and engineer Pham Tuan Thang said, adding that the data decides communications between submarines.

Researchers of the 6th naval squad are proud that they have visited most corners of the sea of Vietnam from the northern gulf southwards to the country’s Hoang Sa (Paracel) and Truong Sa (Spratly) archipelagos in the East Vietnam Sea to the west sea in the Gulf of Thailand.

On the mainland, Vietnam has the two biggest granaries in the north and in the south and it is similar to the seabed offshore the nation, said engineer Dai.

The connection of the two granaries is the Truong Son chain of mountains. Under the sea, there are high mountains to link the two plains underwater.

The height of underwater offshore mountains in Vietnam reaches around 4,700 meters, forming a complicated structure on the seabed.

It is interesting to see such high mountains lying totally under the mysterious ocean, said Dai.

The main difference is the forest of trees at the Truong Son chain on the mainland and coral reefs underwater.