The research dwells upon the dynamics of marine shaft line models. It provides an overview of the key scientific publications confirming the need to continue experimental studies of the processes co-occurring with the operation of shaft lines. The upgraded designs of experimental units for studying transverse, torsional and axial vibrations of shafts and shaft lines are presented. The results of the first experiment are given in the form of tensograms of transverse shaft vibrations. The equations connecting the output values and the impacting factors are obtained in the form of an interpolation polynomial. The authors provide a quantitative assessment of the influence of the slope angle of the ship’s shaft model and the gap in the deadwood bearing on the frequency of occurrence of an unstable condition. The design of the experimental unit for the second experiment is described. A special feature of the design is the addition of a small experimental pool, which makes it possible to adapt the optical method of recording the operating parameters of rotary systems to study the operating modes of the propeller shaft in bearings with a gap. The experiment procedure is given, which allows simultaneously taking into account transverse vibrations arising from shaft bending deformations and from shaft movement inside the bearing. Based on the results of frame-by-frame processing of the motion recording, data on the trajectories of shaft movement in the bearing are systematized and presented. Five separate modes of operation of the propeller shaft at different rotational speeds are characterized. The values of the operating normal stresses are given in the form of tensograms obtained with a measuring system. We make a special mention of the fact that in the mode of shaft rolling along the bearing surface, the movement has a parametric nature. It is concluded that the optical method of strain measurement is sufficiently effective for studying shaft vibrations under operating conditions.