Sophie Germain (1776–1831) was a French mathematician, physicist and philosopher who was an expert in number theory. Without her, the Eiffel Tower would probably not exist due to her work on the physics problem of elasticity. Self-taught, she became the first woman to receive the Mathematical Sciences Grand Prize from the French Academy of Sciences in 1816.
It took 18 months to draw up the exacting parameters for the specifications of this cable ship, which will consist of 4000 metric tons of steel and be 100 meters long and 18 meters wide.
Orange Marine has named its new cable ship in her honor. She will be the first ship designed specifically for repairing all types of submarine cables, whether optical fiber telecommunications cables or power cables connecting offshore wind turbines.
Repair vessels are of increasing strategic importance for maintaining global Internet connectivity, more than 98% of which relies on submarine cables. However, despite optimized route planning and protective measures taken during installation, there are, unfortunately, regular interruptions to the operation of these submarine cables. Such interruptions can cause major disruptions to the functioning of the Internet and international telecommunications services. In such cases, a cable ship must take action as soon as possible.
A Maintenance Vessel with a Strong Environmental Commitment
The latest addition to Orange Marine’s fleet has been designed to be operational within 24 hours year round. Her development also represents a significant commitment to the environment, as she will eventually replace the Raymond Croze, the oldest cable ship, which was launched in 1983. Her specifications include a 25% reduction in fuel consumption compared to average existing cable ships. “It’s a key driver in saving energy!” said Hugo Plantet, QSE Manager at Orange Marine.
To achieve this, it was necessary to study the Sophie Germain’s hull design. A ship interacts with two elements: the submerged part with the water and the part above the water with the air. For the former, hydrodynamic studies are conducted in large pools (or ship model basins) where real sea conditions such as wind, waves or currents are recreated. The reactions of the model boat’s hull are then measured. “Impacts on speed as well as stability are tested above all, so the hull design can be optimized to the best possible degree.” For the latter, tests have been carried out so that the effect of the wind (or windage) on the ship is reduced as far as possible, thereby limiting the risks of drift. These tests may even result in the ship having fewer decks than in the original design. “We made this decision for the Sophie Germain, which will have one deck fewer than the other cable ships.”
4000 Metric Tons of Steel, 100 m Long and 18 m Wide
In total, it took 18 months to draw up the exacting parameters for the specifications of this cable ship, which will consist of 4000 metric tons of steel and be 100 meters long and 18 meters wide. She will travel at a speed of 12 knots and her target fuel consumption has been contractually planned. “If discrepancies are noted once the ship sets sail, the manufacturer will be penalized,” said Hugo Plantet.
Fuel consumption has been reduced in particular thanks to Azipod technology, which uses azimuth thrusters capable of rotating 360°. The flow is thus optimally directed and allows the ship to be highly maneuverable to remain on course with a defined heading whatever the external elements. This type of propeller also makes it possible to replace the rudder by connecting the electric motor to the underwater propeller, “like on a speedboat.”
A Hybrid Ship, Combining Generators and Batteries
Another technological feature is the generators, which are essential for all diesel-electric systems, such as those used on cable ships. On the Sophie Germain, they will be able to produce up to 6 megawatts of electricity (divided into 2 x 2 megawatts and 2 x 1 megawatts) to power the propellers, and will be used alongside batteries. This so-called “hybrid” configuration will reduce the number of generators used while maintaining the redundancy needed for safe maintenance of cables if a generator unexpectedly shuts down. “We can thus prevent being in a blackout situation, which simply cannot be allowed to happen from a safety and operational standpoint — especially if, for example, we were welding an optical cable. The backup battery system takes over from the failed generator while reducing the boat’s fuel consumption,” Hugo Plantet explained.
In order to reduce the environmental footprint in terms of nitrogen oxide emissions, the ship has a system similar to a catalytic converter on diesel exhausts. When she has been docked, the ship will be electrically connected to the land-based network and will not produce any direct emissions. Solar panels installed in her home port in La Seyne-sur-Mer will supply her with energy that is low in greenhouse gas emissions, covering a large part of her energy consumption when docked. Not to mention the low-sulfur diesel used by Orange Marine’s entire fleet.
Seawater into Fresh Water
Finally, the crew will consist of about 60 people, who will be able to live self-sufficiently for 35 days. The Sophie Germain will be able to store up to 400 m3 of fresh water for the different requirements on board the ship. If that weren’t enough, the cable ship is equipped with fresh water generator systems that convert seawater into fresh water by bringing it to a boil in a vacuum. Numerous methods have also been planned to reduce waste and reprocess it on land.