Analysis of the manoeuvrability and structural strain of a coordinated rudder on an operational tug

Abstract

We have tested and compared the manoeuvrability of an operational tugboat with two different configurations of the steering system: the first one had a steering nozzle with a conventional fixed rudder blade; and the second had the same steering nozzle with a coordinated rudder, consisting of a pivoting flap fitted on the after part of the nozzle blade. It was found that the configuration using a coordinated rudder provided a considerable improvement in the low-speed manoeuvrability of the tug. We abo developed equations for this coordinated rudder configuration which allow us to calculate the final turning diameter, the torque on the stock and the shear forces on the steering system of the tugboat as a function of the propeller shaft speed