RESEARCH ON THE MANOEUVRABILITY 

 AND PROPULSION OF 

 VERY LARGE TANKERS 



J. D. van Manen, M. W. C. Oosterveld, and J. H. Witte 

 Netherlands Ship Model Basin 

 Wageningen, The Netherlands 



ABSTRACT 



This paper deals with the results of investigations into the manoeuvra- 

 bility and propulsion of large tankers, equipped with an advanced stern 

 arrangement for propulsion and ship-control. Authors suggest to 

 eliminate partly or completely the rudder, provide the ship with an ex- 

 tremely cigar- shaped afterbody having a shrouded propeller with a 

 large hub-to-diameter ratio and fit both bow and stern thrusters to the 

 ship. The application of cargo-pump-driven lateral thrusters working 

 on the ejector principle is discussed. 



1. INTRODUCTION 



The requirements for the manoeuvrability and propulsion of very large 

 tankers, to be built in the near future, open the question whether conventional 

 solutions for the stern arrangement still have to be maintained. 



The increasing displacement of tankers results in an increase of the re- 

 quired shaft horsepower. The nonuniformity of the flow at the propeller and the 

 high required shaft horsepower may lead in many cases to vibration troubles 

 and cavitation-erosion damage on the propeller blades. The increasing size of 

 tankers and the difficulty of developing port areas large enough to accommodate 

 them will lead to higher requirements with respect to the effectiveness of the 

 ship-control devices. The effectiveness of a rudder strongly depends on the 

 ship speed. As speed decreases, the effectiveness of the rudder becomes less 

 and less. 



In an attempt to provide large tankers with propulsion devices with superior 

 cavitation and propeller -induced vibration characteristics in addition to a high 

 propulsive efficiency and to provide tankers with a greater degree of manoeuvra- 

 bility, the authors suggest to eliminate the rudder, provide the afterbody of an 

 extremely cigar-shaped stern with a shrouded propeller having a large hub-to- 

 diameter ratio and fit both bow and stern thrusters to the ship. In Fig. 1, the 

 installation of the propeller in a clear plastic nozzle on the afterbody of a tanker 



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