Abstract
Referred to the equivalent turbine-propeller shafting with a mass at the thrust block joined to the supposedly rigid double bottom through a spring and also to another mass at the propeller through another spring, (1) the equation of the fundamental axial natural frequency is confirmed in order to correct a false equation written in two Japanese books, and (2) the frequency is calculated and compared with the measured one for a shafting shown in the paper by Rigby and also for five shaftings shown in the paper by Couchman so as to justify a more reliable description of the equivalent system than those given in three Japanese books.
