## 1 Introduction  
Due to the limits in fossil fuel reserves and the environmental problems caused by their combustion (since these are primarily responsible for greenhouse gases (GHG) [1, 2]), numerous countries have made energy transition policies that highlight the need for less-polluting alternative energies, such as renewable energy. In the Paris agreement [1], it was established as a priority objective to achieve a 20% reduction in greenhouse gases compared to 1990 and to increase to 80% in 2050 [3]. During the last few years, the European Union has developed significant methods to increase electricity generation using renewable resources. The fraction of renewable energies in the final electrical consumption increased from 8.5% in 2004 to 17% in 2016 [4]. Among renewable energies, one of the greatest possibilities is wind energy, representing 28% of the additional renewable capacity [5]. In 2018, at least twelve countries around the world achieved or exceeded 10% of their annual electricity consumption using wind resource. In the offshore context, seven countries on the European continent and two on the Asian continent produced 4.5 GW, raising the cumulative global capacity by 24% to 23.1 GW. The success of offshore wind energy in Europe has generated interest in other regions. The future of wind energy will be focused on repowering onshore wind farms [6; 7] or installing wind farms in offshore waters, where the wind resource is higher, but where there are other factors, such as areas where the farms cannot be installed (navigation areas, protected regions, etc.) [8]. Within the field of marine wind energy, it is important to show the evolution of this type of energy since 1991 [9; 10]. In this year, the first offshore wind farm was built on the island of Lolland (Denmark). This offshore wind farm was named Vindeby Offshore Wind Farm [11] and was built by the Elkraft company (Lolland, Denmark), one of the predecessors of today's giant marine wind power company DONG Energy [12]. At that time, marine wind power was somewhat symbolic. The park was composed of 11 wind turbines with a power of 450 kW each, totaling 4.95 MW of power. From that moment, different technologies for the production of wind energy on the high seas began to be studied and their evolution through the years has been remarkable. It is expected that in the year 2030, 190 GW of offshore wind will be installed [13]. There are two main types of structures for the use of marine wind energy: those that are fixed [14; 15; 16] to the seabed and floating structures. Fixed structures are designed for depths less than 50 m and floating structures for depths greater than 50 m. Among the fixed structures we can talk about monopole, triple, jacket, gravity structures. Within the floating structures we can talk about the Tension Leg Platform (TLP), spar, semi-submersible, TELWIND, SATH [17; 18; 19; 20]. The SATH(r) (Bilbao, Spain) concept means Swinging Around Twin Hull [21] and it is a new concept of floating offshore wind structure developed by the Spanish Saitec company (Bilbao, Spain). It is a semisubmersible concrete floating offshore wind structure. It has a Single Point Mooring system based on a structure that connects all moorings and the main electric cable to the same point in space. The main advantages of the SATH(r) concept regarding other platforms are [21]:  
* Total onshore construction. * Use of high-durability concrete, reducing maintenance costs. * Worthy scalability of the turbine size for mass production of large wind farms. The main disadvantage of this new concept is that it needs time to be proven on the sea in order to increase its grade of development and produce it commercially. One of the main problems of marine structures is the severe working conditions they are subjected to. Among these, marine corrosion occupies a very important role [22]. This causes the cost of these platforms to rise since the cost of maintenance is very high. As a result, their profitability decreases.