This study evaluates the mooring system of FPSO/FLNG using the Gaidai reliability method. FPSO is an offshore vessel used for producing, storing, and offloading natural gas or crude oil. FLNG is the equivalent of natural gas in floating form. Accurate prediction of extreme mooring hawser tensions is crucial for design and safety. Excessive tensions during offloading can lead to operational risks. The study uses ANSYS-AQWA software to model vessel dynamics under wave loads. Experimental validation is discussed. A novel multi-dimensional reliability method based on Monte Carlo simulations is proposed. This method efficiently assesses failure or damage risks using available data. It is useful in vessel design for selecting optimal parameters and minimizing mooring tensions. The study benchmarks the Gaidai reliability method, which allows efficient prediction of failure or damage risks for complex offshore systems. The method's key advantage is its multi-dimensionality, covering various system components with different physical dimensions, unlike traditional methods limited to two dimensions. The study focuses on FPSO mooring hawser tensions within offshore operational safety and reliability. Recent studies on hydrodynamic interactions between FPSO and SBS LNG carriers are reviewed. The study performs accurate numerical simulations of SBS dynamic offloading processes using ANSYS-AQWA. CFD investigations are conducted under realistic wave conditions. The study aims to use a multi-purpose MC-based method to analyze non-linear effects in mooring tensions without simplifications. The method has been validated for complex offshore systems. In situ wave statistics are analyzed using satellite data. Wave heights and periods are assessed for the Bohai Bay area. Four random seed simulations are run for each sea state. Wind, sea current, and wave directions are considered for different SBS environmental conditions. The study uses FEM software to model vessel motions and validate numerical results. Key parameters for FPSO and shuttle tanker are provided in Table 1. The study highlights the effectiveness of the multi-dimensional reliability method for FPSO/FLNG mooring systems.This study evaluates the mooring system of FPSO/FLNG using the Gaidai reliability method. FPSO is an offshore vessel used for producing, storing, and offloading natural gas or crude oil. FLNG is the equivalent of natural gas in floating form. Accurate prediction of extreme mooring hawser tensions is crucial for design and safety. Excessive tensions during offloading can lead to operational risks. The study uses ANSYS-AQWA software to model vessel dynamics under wave loads. Experimental validation is discussed. A novel multi-dimensional reliability method based on Monte Carlo simulations is proposed. This method efficiently assesses failure or damage risks using available data. It is useful in vessel design for selecting optimal parameters and minimizing mooring tensions. The study benchmarks the Gaidai reliability method, which allows efficient prediction of failure or damage risks for complex offshore systems. The method's key advantage is its multi-dimensionality, covering various system components with different physical dimensions, unlike traditional methods limited to two dimensions. The study focuses on FPSO mooring hawser tensions within offshore operational safety and reliability. Recent studies on hydrodynamic interactions between FPSO and SBS LNG carriers are reviewed. The study performs accurate numerical simulations of SBS dynamic offloading processes using ANSYS-AQWA. CFD investigations are conducted under realistic wave conditions. The study aims to use a multi-purpose MC-based method to analyze non-linear effects in mooring tensions without simplifications. The method has been validated for complex offshore systems. In situ wave statistics are analyzed using satellite data. Wave heights and periods are assessed for the Bohai Bay area. Four random seed simulations are run for each sea state. Wind, sea current, and wave directions are considered for different SBS environmental conditions. The study uses FEM software to model vessel motions and validate numerical results. Key parameters for FPSO and shuttle tanker are provided in Table 1. The study highlights the effectiveness of the multi-dimensional reliability method for FPSO/FLNG mooring systems.