ABSTRACT

A turning performance of a tow ship towards secure towing operation needs to be investigated comprehensively. This paper presented a numerical analyses of turning characteristic of a tow ship in the towing system. Three different length ratios of the tow ship were employed to pull a towed-barge in the various towline lengths and the tow points. The result revealed that the increasing ratios of L1=L2 is able to reduce the tactical diameter of a tug whilst prevent the loosening towline in the way of turning. In addition, the replacement of tow point (found in paper) towards c.o.g of the tow ship signified her yaw rate, which comprised with the smaller radius of turn.

INTRODUCTION

In general analysis, physical geometry of towing system was composed mainly into three components i.e., towed ship, towline, and tow ship. The study of tow and towed ships system has led primarily to great effort of figuring a secure towing guideline for the ship operator. Several researchers investigated each components comprehensively to identify its effects to their towing stability performances. In conjunction with the first component, Yasukawa, Hirata, Nakamura and Matsumoto (2006); Yasukawa, Hirata, Nakamura and Koh (2007); Lee (1989) presented a nonlinear analysis of the slewing motion and a course stability of the towed ship, respectively in calm water condition. Yasukawa and Nakamura (2007), Yasukawa, Tanaka, Hirata and Hashizume (2007); Kijima and Varyani (1986) carried out both nonlinear and linear analyses of a course stability of the towed ship in the steady wind condition. Hara, Yamakawa, Hoshino and Yukawa (2000) also studied the characteristic of unstable towed ship motions incorporated with her towing resistance in calm water and waves, respectively. In the second component, Hara, Yamakawa and Hoshino (1993) investigated the characteristic of the towline tension during towing.

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