Manoeuvrability of Pusher Barge System with Special Connecting Device

Abstract

Connecting devices of pusher barge systems are classified into two types. One is perfectly rigid type for relative motions between a barge and a pusher, and the other is partially free type. The connecting device of this paper is a latter type, and being free for pitching, heaving, rolling and yawing. So, the peculiar control method is needed, by which the pusher barge system is manoeuvred for an optional direction, on the other hand, growth of the cross angle between pusher's and barge's center lines must be restrained. Free running tests were held to get turning characteristics and frequency response characteristics which are necessary to design the peculiar controller. Then it has been proved that the pusher barge system of this type can be controlled, but under way of turning motion, yaw rate of the barge grow rapidly with some rudder angle. In order to make the strange phenomenon clear, hydrodynamic forces and moments of a pusher and a barge were measured at the circulating water channel, and with the results, the motions of this system were simulated. Consequently, it has been made clear that the cause of the phenomenon is the nonlinear force and moment which appears over some drift angle at the point of skegs.