Recently, several experimental and numerical studies have underlined the advantages of adding clumped weights at discrete positions of mooring lines. To confirm the influence of these weights, an experimental study was performed for a 1:30 scale model of a mooring line. In this study, the clumped weight is modeled as a scaled disc placed at different positions along the mooring line. The series of experiments has been carried out at the CEHIPAR towing tank using a submerged studless chain both with and without clumped weights. The experiments consist of the excitation of the suspension point with horizontal periodic motions using different amplitudes and periods, where the mooring line’s tension at the fairlead is measured using a load cell and a dynamometer, and the motion of a part of the line is recorded using low-cost submerged cameras. Similarly to previous experiments, the fairlead tensions increase with higher amplitudes and lower periods, and a clear pattern in the motions of the line at different depths is found. The dissipated energy and the fairlead tension is also increased by the addition of the clumped weight, and the variation of this energy with its position along the line is monitored. The presence of clumped weights is also implemented into a finite element numerical code, previously validated without clumped weights, where all the previous experiments with clumped weights are replicated with remarkable accuracy. This double experimental and computational approach to the problem provides an important dataset for numerical code validations and opens future discussions about the impact of clumped weights on floating platforms.

The transition towards a low-carbon economy is emerging as one of the most pressing challenges of our era. Among the various sustainable technologies, offshore wind energy stands out because of its potential to significantly contribute to this transition. The international framework is increasingly supportive of offshore wind as a key technology for achieving decarbonization goals, as evidenced by the widespread support it receives in many countries around the globe. However, the expansion of offshore wind technology faces notable technical and economic challenges, particularly with the trend towards installing turbines in deeper waters. This trend is driven by the fact that most of the US coastlines, almost all of Japan's coastlines, and several locations in Europe, including the coasts of Norway, the Mediterranean, and the Atlantic (Spain and Portugal), require the use of floating wind turbines due to their deep-water conditions. This requires longer mooring lines, which significantly increases their weight, and therefore cost. This Ph.D. thesis aims to address one of the new critical station-keeping challenges that arise: the demand for innovative and cost-effective mooring solutions for floating wind turbines. The integration of inertial elements, such as clump weights, into mooring lines is explored to improve the response of floating platforms while reducing costs. Clump weights can significantly enhance the performance of mooring systems if properly designed. In this Ph.D. thesis, different possibilities of clump weight inclusion in single and shared mooring systems of floating wind farms are explored; benefits and counterparts are demonstrated. The methodology adopted along with this thesis is a mixed-method approach that combines numerical simulations with a strong level of experimental validation. First, the hydrodynamics of an isolated clump weight is studied with computational fluid dynamics simulations and experiments. The results are then used to implement these devices in a dynamic mooring line code. In this part of the research it is found that clump weights primarily affect the weight and added mass rather than viscous drag loads in the mooring line. After this, the clump weight is added to the lines of a catenary mooring system of a floating wind turbine and evaluated with numerical simulations in OpenFAST and experiments. The first-order motions remain relatively unchanged, but second-order motions vary due to system stiffness changes, allowing for different offsets. Finally, the contribution of the clump weight in a shared mooring system is explored, in which a reduction of maximum displacements in the horizontal plane and mooring line loads is achieved. In addition, slack/snap conditions are drastically reduced or nearly eliminated. This Ph.D. thesis provides a comprehensive analysis of the influence of clump weights in the mooring systems for floating wind turbines and floating wind farms. Incorporating clump weights in mooring systems can offer a practical solution to improve the economic and technical viability of offshore wind farms. The findings suggest that clump weights can reduce the overall cost of mooring systems by enhancing performance and reducing material requirements. RESUMEN La transición hacia una economía neutra en emisiones carbono es uno de los desafíos más apremiantes de nuestra era. Entre las diversas tecnologías de energía renovable, la energía eólica marina destaca por su potencial para contribuir significativamente a esta transición. El marco internacional apoya cada vez más a la energía eólica marina como una tecnología clave para lograr los objetivos de descarbonización, como lo demuestra el amplio respaldo que recibe en distintos países alrededor del mundo. Sin embargo, la expansión de la tecnología eólica marina se enfrenta a desafíos técnicos y económicos notables, especialmente por su tendencia actual de instalar turbinas en aguas cada vez más profundas. Esta tendencia está impulsada por el hecho de que más de la mitad de las costas de Estados Unidos, casi todas las costas de Japón y varios lugares en Europa, incluyendo las costas de Noruega, el Mediterráneo y el Atlántico (España y Portugal), requieren el uso de turbinas eólicas flotantes debido a la profundidad de sus aguas. Esto requiere líneas de fondeo más largas, lo que aumenta significativamente su peso y, por lo tanto, su coste. Esta tesis doctoral tiene como objetivo abordar uno de los nuevos desafíos críticos en el posicionamiento dinámico de plataformas: la demanda de soluciones de fondeo innovadoras y rentables para turbinas eólicas flotantes. En esta línea, se explora la posibilidad de añadir elementos inerciales, como los clump weights, en las líneas de fondeo para mejorar la respuesta de las plataformas flotantes y así reducir los costes. Los clump weights pueden mejorar significativamente el rendimiento de los sistemas de fondeo si se diseñan adecuadamente. En esta tesis doctoral se exploran diferentes posibilidades de inclusión de clump weights tanto en sistemas de fondeo individuales como compartidos de parques eólicos flotantes; demostrando así sus fortalezas y debilidades. La metodología adoptada a lo largo de esta tesis es un enfoque de método mixto que combina simulaciones numéricas con experimentos a escala. En primer lugar, se estudia la hidrodinámica de un clump weight aislado mediante simulaciones de dinámica de fluidos computacional y experimentos. Los resultados se utilizan luego para la implementación de estos dispositivos en un código de elementos finitos que incluye los efectos dinámicos de la línea de fondeo. En esta parte de la investigación se encuentra que los clump weights afectan...