“Hull structural vibration is an old but a new problem” is often said by many managers. That is because the vibration of the hull structures caused serious problems in old times and still now brings new kinds of problems. Another frequently repeated saying is: “When some area vibrates heavily, reinforcing that part can reduce the vibration. However, these reinforcements are likely to cause vibration in another area.” In this chapter, the change of boundary conditions for the vibration problems is mainly focused both from social and structural perspective. In the former case, for instance, the change of social and economic environments will bring different types of vibration problems. In the latter case, if reinforcements in the vibrating area are provided, they will change the boundary conditions of the surrounding areas.