Manoeuvrability and Propulsion of Very Large Tankers 



Table 11 

 Rudder Steering 



We point out that ^A^gx was not corrected for the increasing effectivity of 

 the rudder due to propeller overload on model scale during the Z manoeuvring 

 tests. This should decrease the average '/'^^^^ value for rudder steering by 10 

 percent. So the above given result for jet steering superiority is on the con- 

 servative side. After contemplating the results of the experiments, it was felt 

 that the nozzles tested were chosen too small. Whether the ship can be ma- 

 noeuvered up till the design speed of 15.75 knots, with a larger nozzle, D^ = 2-4 

 m say, remains to be seen. However nozzles with these small exhaust diame- 

 ters are attractive in connection with main cargo pump-driven steering systems. 

 These installations will be described in the following section. 



4. MAIN-CARGO-PUMP -DRIVEN JET-STEERING SYSTEMS 



Simple Nozzle System 



For a description of conventional lateral thrust units we refer to the publi- 

 cation of Jastram (12) and of Stuntz and Taylor (15). 



265 



