This study presents Dynamic Catenary (DynCat), an extended methodology for simulating elastic mooring lines in free-catenary configurations connected to floating offshore units. Traditional analyses rely either on catenary models, which are computationally efficient but dynamically oversimplified, or on finite element models (FEM), which provide higher fidelity at a greater computational cost. DynCat bridges this gap by combining the low computational cost of catenary models with enhanced physical accuracy, grounded in principles of deformable-solid mechanics. The formulation revisits deformable cable elements within the FEM framework, assembles multi-material line segments into a unified model, and incorporates environmental loading effects, resulting in numerically stable simulations that provide instantaneous line geometry and tension profiles at each time step. Validation studies covering shallow, intermediate, and deep waters under various fairlead motion regimes demonstrate that DynCat maintains good accuracy under low-to-moderate motion conditions. Although its performance deteriorates under highly dynamic deep-water conditions, DynCat remains accurate and robust within the operational envelope of shallow-to-intermediate water depths and low-to-moderate motion intensities, with simulation time reductions of 60–70% compared to conventional FEM approaches. This makes DynCat a promising tool for preliminary design and time-constrained analyses.
