The cost of Floating Offshore Wind (FOW) is driven by the foundation, thus it can be reduced by optimising the floater design from the early stage. Most of the numerical tools for the platform design integrate radiation–diffraction theory-based software, but it can make the whole process very time-consuming since the preliminary design phases usually imply the analysis of a large number of designs. In order to accelerate the first stages of design, and consequently, achieve the foundation cost reduction, this study proposes an efficient methodology for the hydrodynamic added mass, radiation damping, and excitation loads calculation. The method is implemented for a semi-submersible platform, and it is verified against the radiation–diffraction commercial software AQWA. The methodology is validated through a comparative analysis of the response of ten different platforms, and it has shown that the hydrodynamic coefficients derived from either radiation–diffraction analysis or from the proposed method lead to equivalent conclusions. The maximum values of the platform’s pitch angle and the nacelle acceleration are assessed, achieving a maximum deviation among the most critical designs of 3% and 17%, respectively. This methodology has demonstrated to provide with reasonable accuracy the dynamic behaviour of the offshore wind substructures achieving a significant computational cost reduction compared to the state-of-the-art methods, which enables to accelerate the optimisation process and thus, resulting in a more accurate floater preliminary design.

漂浮式海上风电（FOW）的成本由基础驱动，因此可以通过前期优化浮式设计来降低成本。大多数平台设计的数值工具都集成了基于辐射衍射理论的软件，但由于初步设计阶段通常意味着对大量设计进行分析，因此整个过程非常耗时。为了加速第一阶段的设计，从而降低地基成本，本研究提出了一种有效的水动力附加质量、辐射阻尼和激励载荷计算方法。该方法在半潜式平台上实现，并通过辐射衍射商业软件AQWA进行了验证。该方法通过对十个不同平台的响应的比较分析进行了验证，并且表明从辐射衍射分析或所提出的方法得出的流体动力学系数得出了等效的结论。评估了平台俯仰角和机舱加速度的最大值，实现了最关键设计之间的最大偏差分别为 3% 和 17%。事实证明，该方法能够以合理的精度提供海上风电下部结构的动态行为，与最先进的方法相比，可显着降低计算成本，从而加速优化过程，从而获得更准确的结果。浮体初步设计。