There is a demandto develop and evaluate new concepts for offshore structures for harnessing ocean energy. Tools capableof calculatingthe behaviour of this kind of structures are also requestedby the industry. An accurate analysis comprises fully coupled simulations and the use of complex models for non-linear dynamics analysis, including the modellingofmooring lines onfloating offshore structures. In opposite of quasi-staticmodellingof mooring lines such as catenary lines [1],time-dependent models [2, 3] present some advantages.This workpresents a dynamic modelof mooring lines for deep-water structures using LMM (Lumped Mass Method)[4, 5] formulation and its application on differentkinds of floating devices. First, the mathematical model for mooring lines is presented. Then anapplication tool based on that mathematical model is showed. This tool is linked to the time-domain seakeeping solver SeaFEM [6]. The resulting model is able to obtain a fully coupled analysis of seakeeping and mooring dynamics of floating offshore structures. A preliminary study of mooring dynamics is presented over differentsolutions and configurations of mooring lines for severalfloating devices. Furthermore, an optimal design of mooring line configurations for differentsolutions of floating structures can be achieved.This work also presents the study of differentfloating devices under several sea wave conditions. Finallysome conclusions are remarked, and the future research lines are presented.