The loading characteristics of ship’s double bottom tanks subjected to underwater non-contact and contact explosions were researched respectively using AUTODYN finite element software. The loading type of the double bottom tanks during semi-load and full load conditions was analyzed, and the influence of explosive distance and loading condition on the loading characteristics of internal plate was discussed. The result showed that the transmitted shock wave is the major threat of the inner plate in full-load condition; the splashing loading is the major threat of the inner plate in semi-load and non-contact situation; and high-velocity water-jet is the major threat of the inner plate in semi-load and contact situation. Therefore, the semi-load condition of double bottom tanks is strongly recommended to warship in active time.

Applying the hull box girder can improve the longitudinal strength of the structure. The box structure can protect important pipelines and cables in the girder and speed the construction. And it is also beneficial for quality control of construction and easy maintenance of the structure. However, currently the box beam structure is only used in local structures instead of the entire ship. In this article, taking a conventional hull as the base, the box girder was used for the whole ship design in order to improve the ship’s antiknock performance and meet the requirements of vitality. The hull structure was built by a steel box girder to bear the global loading. The hull shape lines and their necessary local stiffness were guaranteed by the light-weight and high-strength composite sheets. Thus, decoupling of local strength and global strength of the hull could be realized in this way. Based on the acoustic coupling method, the response of the hull to explosion was analyzed by means of ABAQUS software. And it as confirmed that the box beam structure has a better antiknock performance. Finally, the design of the hull box girder was optimized for further improvement of the antiknock capacity of the hull.