Some basic knowledge about submarine cables

In recent years, global internet transportation has generally replaced satellites with transoceanic submarine cables to ensure transmission speed and save operating costs. So how are submarine cables made? How is the laying process? Here are some basics about submarine cables.

Manufacturing materials: The core of the submarine cable is made of high-purity optical fiber as thin as hair, which guides light along the path of the optical fiber through internal reflection. The submarine cable must be able to withstand the huge pressure at 8 kilometers underwater, which is equivalent to the weight of an elephant on the thumb. The deep-sea cable manufactured by NEC is made of lightweight polyethylene, and the thickness of the entire cable is only 17 mm.

Manufacturing process: In the manufacture of submarine optical cables, the optical fibers are first embedded in a jelly-like compound that protects the cable from damage even if it comes into contact with seawater. The cables are then encased in steel pipes to prevent the pressure of the water from destroying them. Next, it is wrapped in a steel wire with a very high overall strength, wrapped in a copper tube, and finally covered with a protective layer of polyethylene material. On the coast near the continental shelf, submarine cables are usually laid with lightweight cables paired with stronger steel wires and covered with asphalt coatings to prevent seawater corrosion.

Submarine cable laying: Submarine cable laying mainly includes three stages: cable routing investigation and cleaning, submarine cable laying, and burial protection. When laying the cable, control the sailing speed of the laying ship and the release speed of the cable to control the angle of the cable entering the water and the laying tension, so as to avoid damage to the cable due to too small a bending radius or too large a tension. Among them, when laying in the shoal section, the cable-laying ship stops at a place 4.5 kilometers away from the coast and is pulled by a tractor on the shore to pull the cable placed on the floating bag ashore. After the cable is landed, the floating bag is removed to make the cable sink to the bottom of the sea. When laying in the deep sea, the cable-laying ship releases the cable, and uses underwater monitors and underwater remote control vehicles to continuously monitor and adjust, and control the forward speed and direction of the laying ship and the speed of laying cables to avoid uneven places and rocks to avoid damage to the cables.