Marine propulsion shafting system subjects to various shocks and cycle exciting forces in actual operation. The propeller excitation is an important the marine shafting vibration excitation sources. In this paper, the finite element method is used to calculate a ship propulsion shafting vibration responses under the propeller bearing forces. Propeller bearing forces can be decomposed into components in three directions of forces and three directions of moments, wherein the periodic propeller excitation will cause the longitudinal vibration, torsional vibration and whirling vibration of marine shafting. The mathematical equations governing the dynamics of the circular shaft of regular constant section are derived. Compared with the free vibration systems, it is found that adding the propeller exciting force can greatly change the frequency band for marine shafting vibration isolation.
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