Advanced mooring analyses are performed to design robust solutions for floating offshore wind turbines. The mooring simulations often include features such as wave excitation and hydro- and aerodynamics to incorporate the operating wind turbine and its interaction with the floater in high detail. Next to requirements on overall design stability, floater offsets and dynamic motions, the eigenfrequencies of the design must be sufficiently robust to avoid excitation of resonance by rotor frequencies, first-order wave forces and vortex shedding [1]. Obviously, the eigenfrequencies of the system are directly related to the overall stiffness of the assembly, and the stiffness of the mooring lines plays a crucial role in this. This work aims at developing models that allow more accurate modelling of the response of synthetic ropes, in particular high-modulus polyethylene (HMPE) ropes. As manufacturer of the HMPE fiber Dyneema®, Avient Protective Materials aims at enabling the system designers that use our fiber to perform accurate modelling by providing them with the right material models. This paper will present our recent efforts to develop the Dyneema® 3T Rope Model TM, which accurately characterizes the viscoelastic behavior of ropes made out of Dyneema® in terms of stiffness and damping as functions of the three T’s: Time (frequency), Tension, and Temperature. It will discuss the experimental program to characterize the fiber, establishing the constitutive material model and its link to physics, and the model will be compared with experiments. The model now interfaces with leading mooring analysis software programs, Orcina’s OrcaFlex and Principia’s Deeplines Wind. We believe that this model can eventually lead to the acceptance of reduced safety margins by certification bodies. Thereby reducing the costs of developing safe and reliable ropes for floating offshore wind.