How Does a Cable Laying Ship Function?

When it comes to laying submarine cables, the process is a complex yet remarkable feat of engineering. This article delves into the operational details of one such method used, primarily focusing on the unique design and features of cable laying vessels, like the Long Lines. The methods used vary across cable-laying vessels, but this article will illustrate a typical procedure.

The Tank Design and Its Function

The design of a cable ship, specifically the storage tanks, is a crucial component in ensuring the safe and efficient storage and installation of submarine cables. A cable ship features round tanks with a central core resembling a pan used for making donuts. This design, with its rounded shape at both the bottom and top, ensures a smooth surface for cable storage – no sharp corners to snag or damage the cable. Similarly, the tank's rounded entrance, or birds mouth, facilitates the smooth entry and exit of the cable.

Key Components of Cable Loading

A crane, often referred to as a crinoline, forms an essential part of the operation. The crinoline is a rotating arm that oscillates around the tank as the cable is loaded or unloaded, ensuring a continuous and gradual entry and exit of the cable from the tank. For example, as cable is fed into the tank via the birds mouth, it passes through the crinoline, which guides it into the tank smoothly.

It's vital to understand that submarine cables are not continuous stretches of cable but are equipped with repeaters along their length. These repeaters amplify the transmitted data, making it possible for signals to travel long distances without degradation. Without these repeaters, the data input at one end would not be strong enough to reach the other end successfully.

The Loading Process and Repeater Banks

As each reel of cable is fed into the tank, the cable is guided by the crinoline. Whenever a repeater is encountered, the cable is directed to a specialized unit known as the repeater bank, where the cable is spliced and connected to the next segment. Once the bellows cables have been connected, the cable continues into the tank, allowing the next segment to be loaded safely and efficiently. The loading process continues until the tank is full, at which point, the cable is routed to the next tank, allowing for a continuous and orderly loading operation to be maintained.

The Laying Process

Laying the cable works in reverse to the loading process. When it's time to lay the cable, the process begins with the cable being discharged from the storage tanks. Similar to the loading process, the cable is guided by the crinoline, which ensures a smooth transition from the tank into the water. As the cable is laid out, it passes through spools on the ship, ensuring it is handled gently and not overstressed during the laying operation. This process is conducted carefully to minimize the risk of damage to the cable, especially when it encounters curves or changes in direction.

Ensuring the Cable's Integrity

During the laying process, the cable is subjected to numerous forces and stresses, including the weight of the cable itself, the tension applied during laying, and the dynamic forces encountered during the installation. To protect against these stresses, each tank on the ship is designed to handle the cable’s weight and dimensions. The ability to route the cable from one tank to another ensures that the cable is always being handled in a controlled and safe manner, preventing any damage or misalignment.

Conclusion

The complex process of laying submarine cables is a testament to the engineering prowess and precision required in modern telecommunications infrastructure. The layout and function of a cable ship, particularly the round tanks with their crinolines and repeater banks, play a critical role in this process. Understanding these components and their workings is essential for ensuring the reliability and longevity of submarine communication cables.