Author(s)

E. Cueto, J.J. Achutegui, S. Mendiola & G. Gutierrez

Abstract

We have accomplished, in an operating tugboat, a series of manoeuvres in order to determine new relationships between the turning circle diameter, the revolutions of the propeller, the torque in the rudder stock and the most significant stresses. The tests have been accomplished with two configurations, the first one with a steering system composed by rotating nozzle and a fixed rudder blade, and the second with a fixed nozzle with two coordinated helm blades. 1 Introduction The discovery of the Kort nozzle in 1933, for the propulsion of tugs where traction is the main task, was consolidated in the 1970s, after tests showed an increase in the bollard pull of 20% to 35%, depending on their design. Such an increase led to the gradual but wide installation of fixed nozzles. There were two practical results: The first o

Keywords