Naval vessels are not regulated by the class rules, but by the special regulations. Light weight structural design for naval vessels is required, because light weight naval vessels show good action in combat in point of speed, movement, safety and maintenance for same size naval vessels.
This paper introduces the concept and characteristics of the regulations of U.S. Navy which has been the most reliable standards in design of naval vessels, and intends to help designers to comprehend the effect of each regulation on design results.
Also, an optimum structural design method combined with the structural analysis theory is proposed for naval vessels following the regulations of U.S. Navy and is applied to design of a real naval vessel. After application of the optimum design method, its validity is shown and an optimum design of midship section is obtained. This study is focus on navel surface ships(100m class) and hovercrafts(20m class).
From the results of this study, bending moment in sagging is important by the class rules. However, bending moment in hogging is possibly important by the special regulations which include rigid rules rather than the class rules in view of plate dimension to reduce weight of naval vessels. It is known that increasing height of web frame and decreasing breadth of flange frame in beam are good to reduce weight.
Also, the optimum structural design including grillage analysis of frame which is based on design criteria of naval vessels is shown. Light weight can be obtained by space variations of plate-stiffener combination. In addition, the optimum spaces of longitudinal and transverse web frames are found and the effect of main design variables can be investigated.
Therefore, investigation on structural characteristics and requirement for light weight of naval surfaces ships and hovercrafts are shown. Constraints on scantling are shown by the study on the regulations of U.S. Navy. Also, optimum structural design is shown and applied to design of naval vessels and hovercrafts to check its validity.