Q9
(a) Explain what is meant by:
(6)
(i) Wave-making resistance
(ii) Frictional resistance
(iii) Eddy-making resistance
(b) When a ship is 800 nautical miles from port its speed is reduced by 20%, thereby reducing the daily fuel consumption by 42 tonnes and arriving in port with 50 tonnes on board. If the fuel consumption in t/h is given by the expression (0.136+0.001V^3) where V is the speed in knots, estimate:
(10)
(i) The reduced consumption per day
(ii) The amount of fuel on board when the speed was reduced
(iii) The percentage decrease in consumption for the latter part of the voyage
(iv) The percentage increase in time for this latter period
Reference Answer
### Part (a): Ship Resistance Explained **(i) Wave-Making Resistance** Wave-making resistance is a component of the total resistance experienced by a ship moving through water. It is the energy expended by the hull to generate and maintain the wave systems at the bow and stern. * **Mechanism**: As the ship moves, it displaces water, creating an area of high pressure at the bow and low pressure at the stern. This pressure distribution generates a series of waves that radiate away from the hull, carrying energy with them. This energy must be continuously supplied by the ship's propulsion system, and it manifests as resistance.
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