Current knowledge regarding the assessment of forward and sideways accelerations on human safety onboard the high-speed craft (HSC) remains limited, and most conventional shock mitigation seats for these vessels are designed primarily to mitigate vertical accelerations. This study analyzes recorded accelerations onboard a high-speed craft (HSC) in multiple directions to evaluate the effects of forward, sideways, and vertical accelerations on human health and comfort in accordance with ISO 2631-1:1997. To address the shortcomings of conventional seat systems, this research proposes a shock mitigation seat model that incorporates both forward and vertical suspension systems. A mathematical model is developed to predict the seat’s ability to reduce multidirectional acceleration exposure, with an emphasis on vertical acceleration—the direction with the highest intensity—and the forward direction, which is often overlooked in existing designs. The results demonstrate that combining forward and vertical suspension systems in seat design can significantly reduce health and comfort risks associated with accelerations in these directions. This study provides a foundation for future innovations in HSC seat design and encourages the integration of forward suspension systems to enhance occupant safety and comfort.