Manoeuvrability and Propulsion of Very Large Tankers 



Advanced Propulsion for a High-Powered Tanker with Bow 

 and Stern Thruster Control 



In the introduction the elimination of the rudder was suggested by providing 

 large tankers with bow and stern thrusters for transverse control. The elimi- 

 nation of the rudder opens the possibility of extremely cigar -shaped sterns. A 

 complete nozzle ring can be fitted then, attached with four brackets to this 

 afterbody. 



The presence of a rudder on a single-screw ship tends to improve the pro- 

 pulsive efficiency. In addition, the tailpiece may be attractive from a viewpoint 

 of course stability. Therefore, a fixed tailpiece must be fitted to the nozzle 

 ring. In Fig. 1, such an afterbody arrangement is shown. 



Model tests have been carried out to obtain a comparison between the pro- 

 pulsive quality of tankers with a conventional stern arrangement and with the 

 stern arrangement indicated in Fig. 1. The different stern designs have been 

 made for a 90,000-ton deadweight tanker, having an engine power of 18,000 SHP 

 and a speed of 15.75 knots. The principal particulars of the tanker are given in 

 Table 3. 



Table 3 

 Principal Particulars of Tanker 



Loaded Condition 



Light Condition 



Draft 8.13 m 



Moulded volume 65,664 m^ 



The body plans and the screw arrangements of the afterbody variations are 

 presented in Fig. 10. The scale of the model is 38. 



The characteristics of the various propellers are given in Fig. 11. The 

 screw for the conventional model was designed according to the circulation 

 theory for wake -adapted propellers. 



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