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.