With the fast increase of the population on earth, the supply of resources from land is approaching the limit. More and more people have realized that in order to achieve a sustainable economic development, the resources in the ocean have to be relied on. This is because in the wide ocean whose area exceeds more than two thirds of the earth surface, there exist very rich resources such as sea chemical elements, minerals under the bottom, tidy energy and ocean biological resources.

　　The 21st century is a century of ocean. Many new industries such as ocean oil and gas, ocean chemical industry, deepsea mining will be formed. In the exploitation of ocean resources and in the utilization of ocean spaces, the international marine community renewed the interest in studying the feasibility of using very large floating structures (VLFS). In order to ensure their safety at sea, their structural responses in the sea are of particular importance. This is fundamentally a hydroelasticity problem. Due to their extreme large sizes, it is a great challenge both in theory and computational efficiency.