Manoeuvrability and Propulsion of Very Large Tankers 



0.5 



1.0 



Fig. 14 - The dimensionless turning 

 moment and side force as a function 

 of V/U according to Ref. 13 



shown. Since T = pAU^ and T = T^ + S signifies the constant thrust of the lateral 

 thrust unit, it appears that T^ increases, passes a maximum and then decreases 

 with increasing ship speed. From these considerations it is clear that bow 

 thruster ship interaction is very important when studying the manoeuvrability 

 capacities of various bow thrusting systems. 



Description of the Experiments 



As mentioned in the preceding sections, two tanker models were built; one 

 model with a conventional screw rudder arrangement and one model fitted with 

 a Hogner afterbody, accelerating nozzle, bow and stern thrusters but without a 

 rudder. In order to compare jet steering with conventional rudder steering it 

 was intended to carry out Z manoeuvring as proposed by Kempf in the shallow 

 water basin of the N.S.M.B. For the Z manoeuvring, the conventional model 

 was equipped with a servo motor for the rudder angle adjustment. The model 

 with jet steering was supplied with a centrifugal water pump and piping leading 

 to the four exhaust nozzles situated at the bow and the stern of the model. In 

 the water supply pipes, two venturi mass flow meters were mounted for meas- 

 uring the water mass flow to the bow and stern thrusters. Servo motor -driven 

 valves built in the water delivery pipes directed the water flow either to the port 



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