Exam Question

(a) What factors influence the frictional resistance of a ship and what formula is used to calculate the resistance? (6)

(b) A ship 120 m long displaces 10500 tonne and has a wetted surface area of 3000 m2. At 15 knots the shaft power is 4100 kW, propulsive coefficient 0.6 and 55% of the thrust is available to overcome frictional resistance. Calculate the shaft power required for a similar ship 140m long at the corresponding speed. f = 0.42, and n = 1.825. (10)