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	Chinese divers hit 300 meters China succeeded in its first 300-meter saturation dive on Sunday morning as three divers returned safe and sound from deep water to their ship.
China succeeds in first-time 300-meter saturation diving China recruits six aquanaut cadets for deep-sea exploration

Procedures

Illustration

The saturation diving vessel, Shen Qian Hao diving boat

The Shen Qian Hao diving boat is China’s first deep-depth saturation diving vessel. It is 126 meters long and a full-load displacement of over 15,860 tons. The ship's entire diving system is composed of a diving bell, an airlock cabin, a cabin capable of accommodating 12 people and an escape capsule. The diving bell can make depths of 300 meters with three divers, who can then swim out of the bell for underwater rescues or maintenance work.

What is saturation diving?
	Saturation diving is a technique that helps those working in deep waters for long periods of time to avoid the painful and even potentially deadly condition. It’s become widely used in wreckage recovery, and underwater construction and exploration.

Breathing
Divers breathe a mix of helium and oxygen, which raises the pitch of their voice.
Pressure
Under 300-meters of water, divers are exposed to atmospheric pressure 31 times stronger than that on the surface.
Eat
Food is prepared by a dedicated chef and delivered through a round opening in the living chamber. Divers are restricted to a soft-food diet, as chewing can damage their teeth. Divers are kept away from foods that cause flatulence, such as soybeans.
Sleep
There are six bunk beds in the 11-meter-long living chamber. While divers require over 12 hours of rest a day, they are unable to turn off the cabin lights.
Defecation
Divers report to monitors on the ground before and after using toilet and taking a shower. Divers are only allowed to flush the toilet and turn off the water release valve after receiving monitor approval. The waste is then sent through another system of valves and deposited in a storage tank.
Clothing and gear
As temperatures hover between 38 C to 40 C, divers wear loose-fitting cotton clothing. While diving, hot water suits, or special suits that circulate hot water through an intricate network of webbing, are required to maintain body temperatures.

Source: Beijing News

Development

To date, eight countries, namely Britain, the US, Switzerland, Norway, France, Germany, Japan, Russia, have succeeded in 400-meter saturation dives.
In 1957	Humans were first found to be able to handle prolonged exposure to different breathing gases and high pressure environments through American scientist George F. Bond's Genesis project.
In 1962	The American Navy's "Man-in-the-Sea" Program conducted the first saturation dive in the world.
In 1988	French divers reached a depth of 534 meters using the saturation diving technique.
China has made impressive achievements in marine research in recent years.
In 1989	The Chinese navy conducted its own experiments, setting a dive record for Asian countries at the time.
In 2006	A locally developed saturation dive system took divers to 103.5 meters under the South China Sea on a rescue mission in November 2006.
In 2007	Construction of the 300-meter saturation dive system began in November 2007.
In 2012	The Jiaolong, China's most advanced manned submersible, achieved a record dive depth of over 7,000 meters.
In 2014	China succeeded in its first 300-metre saturation diving on January 12 as three divers returned safe and sound from deep water to the living chamber on the ship.
Source: Agencies

Significance

The breakthrough is that divers can complete deep sea tasks that machines can not. The technique can be widely used for on-sea petroleum exploration, installation and maintenance. The 300 meter achievement has been a threshold for China to enter the advanced ranks of the world when it comes to deep sea diving. So far only eight countries have mastered the technique and all have blocked exports of this technique to other countries.

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