Most existing studies did not consider the elasticity of propeller. A simplified model of propeller composed of beam and spring oscillator is constructed. The impact of different simplified modes of propeller on the longitudinal vibration of propulsion shafting is analyzed and the impact of the relationship between umbrella modes frequency of propeller and longitudinal vibration modal frequency of shafting is studied. The results show that the umbrella modes of propeller have distinct embodiment in longitud...