In analyzing the vibration of hull girder or tank wall in contact with fluid, the influence of virtual mass is one of the most important factors to increase the accuracy of analysis. Previous calculation method used the source or doublet respectively, however actual vibration of structure is frequently combined free edged plates with both side in water and tank walls with oneside in water. Then authers made the analyzing method with combined with source and doublet, and confirmed that this method is practically effective for the vibration of ship structure in fluid. This paper show these analyzing method and few calculation examples of ship structure vibration.
