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Q8. A ship 156 m in length, 22 m breadth, displaces 19700 tonne when floating at a draught of 8 m in sea water of density 1025 kg/m³. The ship’s propeller has a diameter of 5.5 m, a pitch ratio of 0.9 and a blade area ratio of 0.45. With the propeller operating at 1.8 rev/s, the following results were recorded:

Apparent slip ratio = 0.05

Thrust power = 1250 kW

Propeller efficiency = 66 %

Calculate EACH of the following for the above condition:

(a) The ship’s speed; (3)

(b) The real slip ratio;(6)

(c) The thrust per unit area of blade surface; (4)

(d) The torque delivered to the propeller. (3)

Note: The Taylor wake function w, is given by w = 0.5 Cb – 0.05