Heave and pitch motions performance of a monotricat ship in head-seas

Abstract

A reliable investigation which allows an accurate prediction on seakeeping performance of a monotricat ship in head-seas is obviously required. To achieve this objective, a Computational Fluid Dynamic simulation approach is proposed by looking into attainable outcomes with precision, whilst a hydrodynamic description that is underlying the rationale behind the results is explained. Two conditions of the monotricat ship model, termed as with and without stepped-hull, were employed in the computational simulation. Several wave properties, such as various wavelengths and wave heights on heaving and
pitching performances associated with different Froude number (Fr) were taken into account. The results showed that the increase of Fr was proportional with the increase the heaving and pitching motions. These led to the downgrade seakeeping performances presented in the form of high Response Amplitude Operators (RAO). In shorter wavelengths (λ<1), RAO of the heave and pitch motions were insignificant. However, the subsequent increase of wavelength (λ>1) was proportional with the increased RAO of the heave and pitch motions. The further increase in wavelength (>1.75) resulted in less RAO both of the heave and pitch motions. The increase in wave height had affected a
proportionate increase in the heave and pitch motions that may possibly lead to degrade her seakeeping quality. It can be concluded that the effects of Fr and wavelength on the heave and pitch motions of the monotricat ship had more complex phenomenon as compared to the wave-height ones. These CFD results are useful as preliminary prediction for navigation safety during sailing.