Why do we need to lay the cable in the deep sea? How can we ensure that it is not corroded by seawater?

Submarine cables are cables wrapped with insulating materials and laid on the sea floor for power and telecommunication transmission.

Submarine cables are divided into submarine communication cables and submarine power cables. Modern submarine cables use optical fiber as the material to transmit signals.

The world’s first submarine cable was laid between Calais, France, and Dover, England in 1850, and the first intercontinental submarine communications cable was completed between Ireland in Europe and Newfoundland in North America in August 1858 by a private British company founded by Cyrus West-Field.

Why was it necessary to place the cable in the deep sea?

The reason is very simple the land has been exploited by human beings leaving very little, and the cable on land planning and laying is very difficult.

Submarine cables are simple to lay, and there is no other way to connect communication between islands and islands, and between countries and countries, but to lay submarine cables.

Now, 99% of the earth’s leap ocean Internet transmission is through the submarine cable transmission of information.

80% of the photoelectric communication on earth is also transported through submarine cable transmission.

The seawater can prevent the interference of external light and magnetic waves, and reduce the noise of submarine communication cable so that users do not feel the time delay.

Submarine cables are divided into two categories: submarine communication cables and submarine power cables.

① The submarine cable we often say in life refers to the submarine communication cable, the cable exterior wrapped with insulating material, mainly used for long-distance communication transmission, such as communication transmission between islands and islands, military information transmission between cross-regions, etc.

② Submarine power cables have a short transmission distance and are mainly used for connecting the ocean between land and islands, rivers, or harbors from the road to transmit power for engineering equipment operating in the ocean, etc.

How is the submarine cable laid?

The laying ship is the most core and key equipment for laying cables, the technology content of this ship is very high, and some countries have only fully mastered this technology in recent years.

Submarine cable laying is done by burying the cable into the submarine mud using a burial plow.

In sandy and silty land high-pressure flushing water to form a 2-meter deep trench, in clay and coral reef areas need to cut a cutter to reach a 0.6 to 1.2 meters deep groove, and then set the cable or fiber into the deep groove natural backfill.

If the design area through which the cable passes happens to be a hard rocky area, the equipment cannot dig a trench or cut a groove on top of the rock.

In this case, the only way to sink the cable naturally into the rocks on the seafloor is to cover the cable with an object that serves as protection for the cable, such as a rock sheet or concrete slab.

How are cables under the sea protected from corrosion by seawater?

Now the total length of cables laid on the sea floor around the world is nearly 1 million kilometers, and the total length of the Earth’s equator is 40,000 kilometers.

In other words, the total length of cables laid under the sea by human beings today could circle the earth 25 times!

Submarine fiber optics are generally very thick, looking very much like an oil pipeline.

The outermost layer of submarine fiber optic armor is a special material that can effectively keep the internal fiber from the corrosion of seawater, to ensure smooth and safe communication.

Seawater is different from freshwater, seawater contains salt and various minerals, it’s corrosive is very strong, and the general material for a long time in seawater immersion is easy to be corroded.

The outermost layer of submarine fiber optic cable is the polyethylene layer, which is to prevent seawater corrosion.

In addition to seawater corrosion, submarine fiber optic cable also has to withstand the submarine pressure, earthquakes, tsunamis, and natural and man-made factors of the heavy test.

Submarine fiber optic cables and optical fibers also have to prevent the bite of undersea fish, laid in the submarine fiber or cable without enhanced armor protection, it is very easy to have some failure.

But even with strong armor protection, its service life is only 25 years, due to be replaced in time.

Will the cable in the deep sea be scraped by the ship or submarine?

In 1850, Britain and France respectively laid the first cable underwater for the transmission of telegraphs, the initial cable laid in the ocean is deep underwater, in some places where the depth of seawater reaches several kilometers, the cable by free fall plus the pressure of seawater naturally sink under the water, so the original cable laying ships and submarines simply can not touch these cables.

Because fishing boats and submarines simply can not reach a depth of several thousand meters under the sea.

As the world’s technology progressed day by day, communication fiber was laid under the sea in 1960, and this fiber was laid very widely distributed in the ocean.

Initially, the fiber optic was laid shallow, and fishermen trawling in shallow waters could easily drag up the fiber optic cable, and fishing boats broke the fiber optic causing huge losses in the early stages of fiber optic laying.

Later, to ensure the normal communication of fiber optics and reduce losses, there is a special submarine cable laying ship. The submarine cable-laying ship uses machinery to dig a pit several meters deep in the seafloor, and then through the mechanical settings on the laying ship, the cable is laid into the pre-dug pit so that ships and submarines cannot touch the cables and fibers buried deep underground in the seafloor.

At the same time, to further prevent possible damage to the submarine cables and fiber optics by fishing vessels and submarines, detailed markings are made on the nautical charts where the cables are laid and where fiber optics are passing through, and there are corresponding reminder signs on the sea surface.

The laying of submarine cables has brought more convenience to our life, which can make information interoperable from miles away. 99% of transoceanic Internet data transmission is now transmitted through submarine optical fiber, and 80% of optoelectronics communication is also dependent on submarine cables, so it is very important to protect the safety of submarine cables and optical fibers.

Nowadays, the cables in shallow sea areas are buried deep underground, and the location of the cables and optical fibers are marked on the nautical charts of fishing vessels and submarines so that fishing vessels and submarines can go around when passing through these areas.

Oil drilling vessels and some special salvage vessels have eye-catching floats in the operation area if there are laid cables, and there are also eye-catching fiber optic alert signs on the computer screen in the operation area, so there is no need to worry about ships’ submarines causing damage to fiber optics and cables.