Due to the ecentricity of thrust force acting on propeller blades, marine shafts experience whirl while rotating. This directly affect the reactions of the different supports, and consequently causes wear of shaft bearings. This paper is concerned with simplifying the concept for the shafting system in order to estimate the frequencies of whirl and propeller tip deflections. The work is dealing with both; three and four span systems with overhaged propeller. The problem is also studied for both mass and massless shafts. For mass-less shafts systems of any number of spans, general formulae for calculating the frequency of whirl and the deflection of propeller tip are proposed. For shaft systems of distributed mass, a procedure is suggested to calculate frequencies as well as deflections at different supports.