During the thermal launch operation of offshore launch platforms/ships, they will be subjected to the combined effects of rocket impact, wind, waves, and currents. Due to different arrangements of mooring systems, the motion response and mooring stress state of offshore launch platforms/ships are affected, which in turn affects the safety of the platform/ship-arrow. Therefore, this article explores the mooring arrangement of offshore launch ships under the coupling of multiple factors, including the arrangement of mooring point positions and changes in mooring line lengths, and their effects on the motion response and mooring stress state of offshore launch ships. Research has found that placing the mooring point below the waterline of the launch vessel and appropriately increasing the length of the mooring line will be more conducive to the conduct of offshore launch operations, providing technical references for the future layout of offshore launch vessel mooring systems.

The offshore launch platform considering the thermal launch of a rocket at sea has been studied. The Realizable k-ε turbulence model and the three-dimensional potential flow theory are used to study the time-domain motion response of the platform under the impact load of the rocket wake and the combined loads of the wind, wave and current. The heave, roll, pitch and yaw of the launch platform during offshore launching under two sea states are compared and analyzed. The analysis and calculation show that one sea state is more beneficial to the two-way safety of the rocket and the launch platform than the other, and the launch platform should avoid offshore thermal launching in beam waves. In addition, a simple calculation method of the wake impact under offshore launch condition is proposed to obtain the pressure time history of the gas wake impact for single Laval tube, providing theoretical and engineering foundation for the subsequent study of the structure and motion performance of the launch platform.