This study presents a novel multivariate risk assessment method for evaluating the lifetime of FPSO (Floating Production Storage and Offloading) and LNG (Liquefied Natural Gas) vessels, particularly during SBS (Side-By-Side) offloading operations. The method, called the Gaidai risk assessment method, is designed to handle complex, high-dimensional dynamic systems and assess the risks associated with critical components such as hawser tensions. The approach involves numerical simulations and Monte Carlo (MC) methods to evaluate dynamic system failure, hazard, and damage risks. The method is validated using real-world data and laboratory experiments, and it provides confidence intervals for predicted risk levels. The study highlights the importance of accurately predicting hawser tensions during offloading operations to ensure operational safety and reliability. The Gaidai method is particularly effective in handling multi-dimensional risk assessments, which are essential for systems subjected to severe environmental conditions. The method is applied to FPSO and LNG vessels, considering the unique challenges of SBS offloading, including the dynamic interactions between vessels and the potential for significant hawser tensions. The Gaidai risk assessment method is based on a multi-dimensional spatiotemporal analysis, which allows for the efficient and accurate evaluation of dynamic system risks. The method is validated against direct MC simulations and experimental data, demonstrating its effectiveness in predicting system failure probabilities and lifetimes. The study also discusses the limitations of traditional reliability methods, which are often restricted to two-dimensional analyses, and emphasizes the advantages of the Gaidai method in handling high-dimensional systems. The results show that the Gaidai method provides a more conservative estimate of system lifetime and accurately predicts the survival probability of dynamic systems under various environmental conditions. The method is particularly useful for complex offshore systems, where traditional methods may not be sufficient. The study concludes that the Gaidai risk assessment method is a robust and effective approach for evaluating the lifetime and reliability of FPSO and LNG vessels, especially in high-dimensional and dynamic environments.This study presents a novel multivariate risk assessment method for evaluating the lifetime of FPSO (Floating Production Storage and Offloading) and LNG (Liquefied Natural Gas) vessels, particularly during SBS (Side-By-Side) offloading operations. The method, called the Gaidai risk assessment method, is designed to handle complex, high-dimensional dynamic systems and assess the risks associated with critical components such as hawser tensions. The approach involves numerical simulations and Monte Carlo (MC) methods to evaluate dynamic system failure, hazard, and damage risks. The method is validated using real-world data and laboratory experiments, and it provides confidence intervals for predicted risk levels. The study highlights the importance of accurately predicting hawser tensions during offloading operations to ensure operational safety and reliability. The Gaidai method is particularly effective in handling multi-dimensional risk assessments, which are essential for systems subjected to severe environmental conditions. The method is applied to FPSO and LNG vessels, considering the unique challenges of SBS offloading, including the dynamic interactions between vessels and the potential for significant hawser tensions. The Gaidai risk assessment method is based on a multi-dimensional spatiotemporal analysis, which allows for the efficient and accurate evaluation of dynamic system risks. The method is validated against direct MC simulations and experimental data, demonstrating its effectiveness in predicting system failure probabilities and lifetimes. The study also discusses the limitations of traditional reliability methods, which are often restricted to two-dimensional analyses, and emphasizes the advantages of the Gaidai method in handling high-dimensional systems. The results show that the Gaidai method provides a more conservative estimate of system lifetime and accurately predicts the survival probability of dynamic systems under various environmental conditions. The method is particularly useful for complex offshore systems, where traditional methods may not be sufficient. The study concludes that the Gaidai risk assessment method is a robust and effective approach for evaluating the lifetime and reliability of FPSO and LNG vessels, especially in high-dimensional and dynamic environments.