Abstract
We developed the outboard motor (OM) equipped with a new V8 type engine with a V-bank angle of 60 degrees. In OMs, the low vibration performance is important to provide the comfortable cruising. However, in this type of engine, the conventional crankshaft cannot cancel the inertial couples. Additionally, because high rpm range mainly used in OMs, the inertial couples contribute to the engine vibrations. In this paper, we proposed the new crankshaft which can cancel them with no additional parts such as balancers. In the examination of the structure, we performed the parametric study of the crankpin offset angle and the counterweight balance ratio. Finally, adopting the new crankshaft to the OM, we achieved the low vibration performance.
