How is the fibre laid down in the sea?
Before laying the cable, a detailed marine survey is conducted to establish the best route for the cable, help with manufacturing of the cable as well as to understand the impacts of ocean currents as the cable falls to place. A number of different approaches can be taken to lay down fibre in the sea depending on the depth at which the cable is being laid. Close to the shoreline, the cable is laid out from the cable ship to be floated ashore with the aid of divers; it is then buried. In order to protect the cable, a robot submarine plough is typically used to create a 1-3 metre deep trench into which the cable is dropped and the trench refilled. Further from the shore, the cable is laid out from a cable ship and allowed to sink to the bottom of the ocean. This whole process is undertaken guided by the detailed marine survey maps that cover the entire route on which the fibre will be laid.
