Topics on Ship Rolling Characteristics with Advance Speed

Abstract

The effect of advance speed on ship rolling characteristics has been a problem to which many researchers have had their interest for a long time. In line with the speed-up of cargo liners, the speed range of experimental investigations of this problem was extended as high as 0. 7 in Froude number in the recent studies by Obrastsov, Ferguson and Conn and so on. The authors have examined carefully the results of these experiments including their own experimental data and obtained an empirical formula for calculating GM under forward motion. A consideration based on the theorem of moment of momentum was made to get some dynamical concepts. In addition, an experiment was carried to estimate the augmentation of frictional resistance for rolling due to ship advance speed. It is found that the augmentation is a linear function of λ=V/σL (V : ship speed, L : ship length, σ : circular frequency of rolling) and the frictional resistance can be considered small irrespective of advance speed even in case of small model ships of 2 m long.