The boundary element method has been used in this paper to calculate the potential wake fraction of the 8301 twin stern ship,the HS80 high speed passenger ship and large diameter to draft ratio FT8601 pushboat .

The ship performance is an important part of the construction process and ship design and the correcting methods for wake fraction scale effect is the most important essential to ship s speed forecasting.

It is important in ASAC system based on acoustic radiation modes to obtain adjoint coefficient of the radiation modes.

A new piezoelectric sensor strategy is presented to measure the adjoint coefficients of the first 2 radiation modes.

According to the integral characteristic of PVDF film, two PVDF sensors are designed to measure the modal weight coefficient of sound radiation.

Based on the theory of sound radiation and the one dimensional model sensors equation as well as the integral characteristic of PVDF, an experiment is conducted with the simply supported beam as the subject to measure mode 1 and mode 2 weight coefficients of sound radiation by shaping the PVDF sensor.

It is presented radiation modes and radiation efficiencies using relationship between surface normal velocities and surface sound pressure of vibrating structures and gives one definition of the weight coefficient of sound radiation.