Korean Register, HD Hyundai Heavy Industries, Samsung Heavy Industries Publish EEDI Guidelines Maritime Activity Reports, Inc. May 18, 2026 © Korean Register Korean Register (KR) has published the "Numerical Calculation Guidelines for the Determination of the Attained EEDI," developed through a joint research initiative with HD Hyundai Heavy Industries (HD HHI) and Samsung Heavy Industries (SHI). The guidelines establish a standardized methodology for numerical analysis based on Computational Fluid Dynamics (CFD), providing an alternative to the conventional physical model testing previously used to verify vessel energy efficiency. As the International Maritime Organization (IMO) continues to tighten greenhouse gas reduction regulations, the shipbuilding industry has been actively adopting a range of energy-saving technologies, including air lubrication systems and wind-assisted propulsion systems, to improve energy efficiency and reduce carbon emissions. Historically, demonstrating the energy-saving performance of such technologies required physical model testing using scaled vessel models in large towing tanks or wind tunnels, resulting in significant time and cost burdens. In contrast, CFD-based numerical analysis, which uses computer simulations to precisely calculate the flow of water and air around a hull, has emerged as a promising alternative. However, differences in analysis conditions and simulation settings can lead to variations in results, highlighting the need for objective and consistent verification standards. The newly published guidelines systematize the procedure for determining the EEDI reference speed (Vref) using CFD-based numerical calculations into three stages: qualification; validation and calibration; and main computation. The guidelines also clearly define analysis methodologies and reporting standards to ensure the reliability and reproducibility of results. Of particular significance is the inclusion of detailed modeling requirements an