Production and Installation of underwater cables

Cable production

Production facilities of deep sea cables are most often located near ports close to the location where the cable will be installed. The main reason for this is that linear kilometers of cabling required can reach a weight of several tons, therefore manufacturers attempt to reduce the travel time between production facility and site of installation. Deep sea cables come at lengths of around 4 km, which can weigh approximately 15 tons. This presents a logistical challenge for the manufacturer for transporting the optical cable by land and conventional cable drums cannot withstand this kind of magnitude of mass. As an example, transporting such masses requires the entire length of the cable to be laid out in a figure of eight formation on a twin railway carriage, so as not to damage the optical fibers inside the structure.

 

Cable Installation

The cable laying process is long and requires a lot of labour. Firstly, the route should be chosen should be as cost-efficient as possible, and must also take into account safety and the physical limits of the cable design. If not planned correctly, miscalculations regarding the aforementioned factors can greatly increase the cost of the project and its payback period. If cabling is carried out between different countries; permits must be obtained in order to use the coastal waters and carry out cable installation from the countries in question. Geological evaluation of seismic activity in the region, volcanism, the probability of underwater landslides and other natural disasters in the region where the work will be conducted must be carried out prior to installation of the cable. Forecasts of meteorologists must also be taken into account in order to avoid problems during the installation. The geological reconnaissance of the route takes into account a wide range of parameters: the depth, the topology of the seabed, the density of the soil, the presence of other objects such as boulders or wrecks.  Possible deviations from the original route are also analysed in order to save time if problems arise, taking note of required cable extension and evaluating change in cost and length of work. The actual installation process of the cable can be initiated only after all the necessary preparations are made.

 

 The process of installation is clarified by the following animation.

 

Laying fiber optic cable on the sea / ocean floor extends continuously from point A to point B. The cable is laid in the bay on boats and transported to the point of descent to the seabed:

The following photo gives a better representation of the true size of the cable:

 

After the cargo vessel is shipped out to its destination; command handlers carefullly unwind the cable at a certain tension with the help of specialized equipment, taking into account the movement of the vessel to maintain the planned route.

 

Rear view of the vessel:

 

If any problems such as breakage or damage to the cable occur; special anchors are used to lift the cable  to the surface to carry out the necessary repairs.