This paper provides insight into the theory and the applications of the order dispersion by crankpin arrangement, especially focusing on the enhancements of the structural reliability of the crankshaft and the sound quality of the outboard motor. In previous research, we developed the crankshaft which can balance by itself for V8 outboard motor with V bank angle of 60 degrees. We specifically showed the theoretical basis of the balancing and the measurement results of actual vibration levels on boat. Meanwhile, note that the crankshaft has a distinctive structure of crankpin offset angle of 60 degrees, so that combustion interval becomes unequal. As to the combustion, however, we just mentioned the effects on the engine output, not the practicality. In this paper, we firstly clarify the following dual benefits of the combustion in terms of the structural reliability and the sound quality. One is that the order dispersion resulting from unequal interval combustion can reduce the excitation force in stress. Taking the resonance magnification into account in the strength evaluation, regardless of the resonant frequency in the normal rotation range, we could ensure the structure without using components such as dynamic dampers. The other is that the dispersion enhances the sound of outboard motor. It allows excitation energy to be dispersed, leading to quieter and more luxurious sound. Through survey and sound quality evaluation, it is verified that most of the respondents prefer the sound mentioned above. Secondly, based on the results, we discuss the better crankpin arrangement to disperse orders in a wide range of crankpin offset angle. Finally, we define the position of the new designed crankshaft from the multiple standpoints of the structure and the sound.