Lightweight technology is an important development trend of ships. Lightweight hull structure design may lead to novel designs that break through existing standards, including new structures or new materials. Based on an overview of the existing safety assessment system for ship structures, it focuses on the safety assessment process and methods for the lightweight structural design, including alternative design process, novelty evaluation indicators and approaches, and methods for determining structural safety assessment criteria based on limit states. The proposed novelty evaluation and safety assessment methods for the lightweight structural design are then applied for practical analysis of the typical cases of the lightweight structural design for oil tankers, bulk carriers, and container ships from literatures published at home. The proposed novelty evaluation and safety assessment methods for lightweight structural design can provide approaches and methods for the structural safety assessment of the corresponding new or alternative designs.

Aluminum sandwich panels are primarily used on luxury cruise liners and speedboats. The lightweight alterative design for the local structure of the superstructure of a common civilian ship is carried out to expand the application scope of aluminum sandwich panels. The structural configuration and the corresponding type of the connection structure are then determined according to the structural characteristics of the sandwich panel. And the mechanical properties of the superstructure before and after the alternative design are compared and analyzed by using the finite element software ABAQUS. The results show that the superstructure of aluminum sandwich panel have better mechanical properties with the reduced structure weight. It can provide reference for the promotion and application of aluminum sandwich panels in the future.