Maneuverability of a Ship with Rudders on Both Sides of Propeller

Free-running model tests and captive model tests were conducted using a ship model under full- and trial-load conditions to capture the maneuverability of a 498-GT cargo ship ''Jinmon-maru'' equipped with rudders on both sides of the propeller. In this paper, the rudder is called a side rudder (SD-rudder). Similar model tests were conducted using an another identical model, in which only the rudder was changed from a side rudder to a fishtail rudder, to evaluate the model test results. Thus, a quantitative evaluation of the difference in the performance of a ship with a side rudder (SD-rudder ship) and that with a fishtail rudder (FT-rudder ship) was realized. The model tests showed that the turning performance of the SD-rudder ship was inferior to that of the FT-rudder ship. It was revealed that the deterioration of the turning performance of the SD-rudder ship can be attributed to a rudder-angle limitation applied to prevent the hull from touching the rudder.