van Manen, Oosterveld and Witte 



RUDDER STEERING 



<^ r l// z 0. 



Fig. 16 - Definition sketch of some quantities given in Fig. 15 



with the model with rudder steering, p^^^ could be measured as a function of 

 the rudder angle "o for a given ship speed v. When the model with jet steering 

 was used, the dependence of ^^^^ on the jet velocity u was measured for a cer- 

 tain ship speed. For a known u, the cross flow parameter v u and the jet 

 power given by the expression N- = '^(pAU^) 75 HP, could be computed. The 

 experimental data are shown in Figs. 17-20 and Tables 9-11. The diagrams 

 illustrate the fact that the v^^gx "^^ ^ relation has a positive gradient and the /'^g, 

 vs v/u line a negative gradient. 



The steering moment acting on the rudder of a ship decreases with v 

 squared when the speed of the ship is lowered. For jet steering, U and hence Nj 

 can be kept constant when the speed of the ship is lowered. This results in an 

 increase of the turning moment on the ship since decreasing speed results in a 

 lowering of the detrimental interaction effect between jet and hull as described 

 in the preceding pages. So it can be said that when jet steering generates the 

 same ^^^^ as rudder steering with maximum rudder deflection, in the range of 



260 



