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Q8. The wetted surface area of a container ship is 7135 m². When travelling at service speed, the shaft power required is 22500 kW when residuary resistance is 25% Of the total resistance and specific fuel consumption is 0.22 kg/kW hr. Propulsive coefficient, based upon shaft power is 0.6. Friction coefficient in sea water is 1.411 when speed is in m/s with speed index (n) 1.825.

(a) Calculate the service speed of the ship.  (10)

(b) To conserve fuel the ship speed is reduced by 10%, the daily fuel consumption is then found to be 100 tonne.

The propulsive coefficient may be assumed constant at 0.6.

Calculate the percentage increase in specific fuel consumption when running at the reduced speed.  (6)