The Study On Rudder Effect Of Low-speed Ships In Harbor

Along with ships to large-scale, high speed, special-purpose development, maritime transport and river traffic have become more busy and crowded. Thus dangers of marine accidents such as collision,aground in port increase greatly. Ship maneuverability is more required. Rudder's controlling capability has been paying close attention to by professional. Ships' speed is lower in restricted waters. Stopping propeller ships will lose rudder effect in a certain speed. The minimum steering speed mostly relies on the ship experiment and less theoretical researches in the past. Satisfied models for simulation and prediction are even less. So the study on rudder effect is of great practical significance.In view of those, this paper adopts MMG modeling ideas and provides a math model which combined the Kijima model and Yoshimura model. The mixed model was suitable for the entire maneuvering ranges including normal speed, low speed, small and large drift angle and so on. Considering the effect of shallow water, the conclusions researched by Yoshimura was adopted.This article realizes model simulation with MATLAB. Firstly uses the ship experiment to confirm this model accuracy. Secondly navigate in 4 minutes under stopping propeller, full rudder, simulates changes in the course and the rate of course, analyses each factor about rudder effect. At last make a investigation that many seamen(caption,C/O) are consulted about minimum steering speed .Synthesizing their opinions and making simulation with mathematical model, we find that the two results overall are uniform and we can sum up a set of practical conclusions. These conclusions can provide references for pilots.