In wave-energy research and development, the LM model and coupling method discussed above are also widely applied in practical design and analysis. Recently, Hall and Goupee [16] developed an open-source LM numerical code, MoorDyn, to model the mooring systems of wave energy devices without considering the bending elasticity. Using an orthogonal local coordinate system to describe the element orientation, Masciola et al. [17] tried to extend the capabilities of line dynamics and bending effects into the mooring analysis program (MAP), which is a quasi-static module developed for the floating wind turbine simulation software—FAST. An optional loose-coupling arrangement between the LM model and the FAST simulator, as defined in Jonkman [18], was used previously in the WEC-Sim, an open-source wave energy converter numerical simulation tool. In this coupled analysis, two sets of equations of motion are solved—one for the floater and one for the appendages. The fairlead forces are updated within each iteration over the time-step; and the equation of motion is integrated with an implicit or explicit scheme. In most loose coupling models, including both FAST and WEC-sim, time integration of the floater motion solver often uses a large time-step, whereas the mooring line solver uses a shorter time-step to ensure stability of the RK2 explicit integrator in MoorDyn. Enhanced refinements of this coupled system are needed in order to balance the accuracy and efficiency of these coupled models.