A new single-domain multi-launch offshore launch method based on the semi-submersible ship

This work proposes a new offshore launch method using a semi‑submersible ship for single‑domain multi‑launch operations, improving launch efficiency and protecting the platform from gas‑jet damage. Rockets and equipment are mounted on the ship, which is submerged to a predetermined depth so that the launch platform is covered by seawater. Results show that the water layer significantly delays impingement of the gas‑jet core on the platform surface, thereby reducing ablation. A theoretical model is derived to predict the time required for an overexpanded jet to penetrate the water layer, considering added mass and momentum dissipation. Through dimensionless analysis using the Buckingham π theorem, a linear empirical correlation for the dimensionless penetration time is obtained. These findings provide a valuable reference for designing effective offshore launch methods and point toward a new integrated direction for ocean engineering.