Author(s)

I. Asmussen & A. Muller-Schmerl

Abstract

Vibration problems were recently observed on some ships equipped with me- dium-speed diesel engines. Measurements revealed in these cases resonance condition between ignition frequency and H-type vibrations of the engines. As a consequence the excitation forces transmitted from the engines to the founda- tions were drastically magnified. A procedure is described how the natural fre- quency of the corresponding H-type modes can be predicted at the design stage. The procedure is demonstrated on the example of three vessels. The results obtained theoretically are verified by measurements. Generally, it was found that the calculated natural frequencies of the H-modes are in very good agree- ment with the measured values. It is shown that reliable results can only be obtained by considering the stiffness of the engine

Keywords