In this study, direct time domain offloading simulations are conducted without condensing the metocean data using High Performance Computing (HPC). With rapidly growing computing power, from increased CPU speeds and parallel processing capability, the direct time domain simulation for offloading analyses has become a practical option. For instance, 3-hour time domain simulations, covering the entire service life (e.g. 100,000 simulations for 35 years) of a floating platform, can now be conducted within a day. The simulation results provide realistic offloading operational time windows which consider both offloading operation sequence (i.e. berthing, connection, offloading duration and disconnection) and required criteria (i.e. relative responses, loads on hawser and flow line, etc.). The direct time domain offloading analyses improve the prediction of offloading operability, the sizing of the FPSO tank capacity, and the shuttle tanker selection. In addition, this method enables accurate evaluations of the economic feasibility for field development using FPSOs.