Exam Question

With reference to the wake of a vessel:

(a) Explain Wake fraction and Quasi Propulsive co-efficient(OPC).

(b) A ship travelling at 15.5 knots has a propeller of 5.5 m pitch turning at 95 rev/min. The thrust of the propeller is 380 KN and the delivered power 3540 KW. If the real slip is 20% and the thrust deduction factor 0.198, calculate the Quasi Propulsive Coefficient (QPC) and the wake fraction.