This paper presents a comprehensive numerical analysis focused on key design parameters for submarine performance, including resistance, propeller efficiency, and self-propulsion point. The study explicitly examines the DARPA (Defense Advanced Research Projects Agency) Suboff subma-rine model, which is propelled by the INSEAN E1619 propeller from the Italian Ship Model Basin. Initially, steady-state RANS simulations were conducted to evaluate the underwater resistance of the bare hull DARPA submarine. Results were validated against experimental data at various speeds. Following this, the open-water performance of the INSEAN E1619 propeller was analyzed under non-cavitating conditions. Validation over a broad range of advanced ratios was achieved through steady-state RANS simulations and a moving reference frame. Subsequently, the self-propulsion point was determined by attaching the E1619 propeller to the DARPA submarine. ITTC (International Towing Tank Conference) standards were followed to align propeller thrust with hull resistance. These steady-state solutions employ the coupled solver along with the SST k-ω turbulence model and a pseudo-transient approach. All simulations leveraged the ANSYS Fluent GPU solver, yielding significant performance improvements when compared to CPU-based solutions.