A Comparison Of Ship Maneuvering Characteristics For Rudders And Podded Propulsors

A comparison of a high speed container ship using a rudder versus a podded propulsor is made to study replacing a rudder with a pod. A mathematical model is altered to simulate a ship operating with a rudder and with a pod to maneuver. The model incorporates the nonlinear maneuvering equations and couples the surge and sway forces, yaw and roll moment, and the roll angle induced during a steady turn with varying rudder and pod angles. The model uses the hydrodynamic derivatives and coefficients for a high speed container ship. The equations are numerically integrated in order to predict the roll angle, sway and surge velocities, and the ship's position in the xy-plane. Both transient and steady state results are utilized to quantify the relative efficiency of each system. The results are used as a preliminary study into replacing a rudder on a ship with a podded propulsor. The results indicate that the ship responds faster and has a shorter turning radius with the pod at lower initial speeds and pod angles, while the rudder responds better at high speeds regardless of angle. Further research is necessary to study the effects of changing the pod's position and increasing the number of pods used.

Vessels ftted with azimuthing podded propulsors have much better maneuvering capabilities. They are also environmentally friendly with much reduced exhaust emissions. With these unique features ,they offer signifcant economic, safety and environmental advantages to society, but unfortunately, the routines and the emergency procedures of the azimuthing podded propulsion system were not clearly defned and incorporated into onboard ISM systems. Masters, Chief Engineers and Pilots should receive a specialist training before they lay their hands on the controls, but instead most of them still have to try learning on the job, which sometimes lead to serious incidents, near misses and accidents with serious consequences. One of the reasons that encouraged me to write this book is to draw attention to these serious shortcomings which someday may cause society to pay a high price. My main focus in this book has been on telling about the shiphandling behaviours of electrically-driven azimuthing propulsors rather than the mechanically-driven azimuthing propulsors. Despite the fact that the shiphandling principles of both systems are quite similar, I chose not to mention much about the mechanically driven azimuthing propulsors as they are mostly related with tugboats. Tugboat handling is another speciality, which I believe should be explained only by seasoned tugboat captains themselves. I am a professional maritime pilot but an amateur author and this book is solely intended to share my humble experience and knowledge with my colleagues, ship captains, students and all other interested parties of the maritime industry. Dear Reader, I had actually started writing this book in order to keep my experience on the subject in writing and bring together all the data I have collected from various resources at different times. To improve my knowledge and experience, I have also joined a special manned model course for “Pod Handling and Emergencies” at Port Revel Shiphandling Centre which is located at Grenoble, France in May 2010. Vessels ftted with azimuthing podded propulsors have much better manoeuvring capabilities, such as reduced turning diameters and signifcantly shorter stopping distances compared to the conventional systems with a fxed propeller and conventional rudder. They are also environmentally friendly with much reduced exhaust emissions. With these unique features ,they offer signifcant economic, safety and environmental advantages to society, but unfortunately, the routines and the emergency procedures of the azimuthing podded propulsion system were not clearly defned and incorporated into onboard ISM systems. Even class surveyors and Port State surveyors don’t seem to have enough knowledge about this technology. Masters, Chief Engineers and Pilots should receive a specialist training before they lay their hands on the controls, but instead most of them still have to try learning on the job, which sometimes lead to serious incidents, near misses and accidents with serious consequences. One of the reasons that encouraged me to write this book is to draw attention to these serious shortcomings which someday may cause society to pay a high price.

This book demonstrates that different rudder configurations have different hydrodynamic characteristics, which are influenced by the profile, the parameters, and the specific configuration. The author proposes new regression formulas to help naval architects quickly estimate the rudder-induced forces and moments in maneuvering. Furthermore, the author proposes and validates an integrated maneuvering model for both seagoing ships and inland vessels. Using the proposed regression formulas and maneuvering model, the specific impacts of rudder configurations on inland vessel maneuverability are studied. In turn, the book demonstrates the application of Reynolds-Averaged Navier–Stokes (RANS) simulations to obtain rudder hydrodynamic characteristics, and the integration of the RANS results into maneuvering models as an accurate estimation of rudder forces and moments needed to quantify the impacts of rudder configurations on ships’ maneuvering performance. In addition, the author proposes new criteria for the prediction and evaluation of inland vessel maneuverability. Simulations of ships with various rudder configurations are presented, in order to analyze the impacts of rudder configurations on ship maneuverability in different classic and proposed test maneuvers. Offering essential guidance on the effects of rudders for inland vessel maneuverability, and helping practical engineers make informed design choices, the book is of interest to researchers and academics in the field of naval engineering, as well as students of naval architecture. Industrial practitioners working on ship design may also find it beneficial.

The course keeping and manoeuvring requirements for a ship are governed by international maritime law. In assessing and predicting the course keeping and manoeuvring capabilities of the ship, knowledge is required of the rudder forces necessary to keep a course or facilitate a manoeuvre. The second edition of Marine Rudders, Hydrofoils and Control Surfaces includes up-to-date data and rudder design techniques that enable the rudder forces to be estimated, together with any interactions due to the hull and propeller. The new edition describes the design and application of hydrofoils including shape adaptive design, and their applications including hydrofoil craft, yachts, and kite surfing hydrofoils. The professional will also face the need to design control surfaces for motion control, such as roll and pitch, for surface vessels and submersibles, and the book contains the necessary techniques and data to carry out these tasks.This book is for practicing naval architects and marine engineers, small craft designers, yacht designers, hydrodynamicists, undergraduate and postgraduate students of naval architecture, maritime engineering and ship science, and the broader engineering community involved in the development of marine craft that rely on the generation of ‘lift’ such as control engineers and aerodynamicists. Describes techniques for analyzing the performance characteristics of rudders, hydrofoils, and control surfaces Includes extensive design data and worked examples for the analysis of rudder, hydrofoil and control surface performance Provides a detailed examination of the design of hydrofoils

The early development of the screw propeller. Propeller geometry. The propeller environment. The ship wake field, propeller performance characteristics.

Marine Rudders and Control Surfaces guides naval architects from the first principles of the physics of control surface operation, to the use of experimental and empirical data and applied computational fluid dynamic modelling of rudders and control surfaces.The empirical and theoretical methods applied to control surface design are described in depth and their use explained through application to particular cases. The design procedures are complemented with a number of worked practical examples of rudder and control surface design. • The only text dedicated to marine control surface design• Provides experimental, theoretical and applied design information valuable for practising engineers, designers and students• Accompanied by an online extensive experimental database together with software for theoreticalpredictions and design development