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Q8. (a) Define coefficient of fineness of waterplane area, block coefficient and midships coefficient. (b) A box shaped vessel has length 100m and breadth 12m and floats at a range of drafts from 1m to 10m. Produce curves of KB1, BM and KM.

Q8. A. Describe the fundamental principle of a propeller. (6)

B. A propeller 6m diameter has a pitch ratio of 0.9, BAR 0.48 and, when turning at 110 rev/min, has a real slip of 25% and wake faction 0.30. If the propeller delivers a thrust of 300 KN and the propeller efficiency is 0.65. Calculate - i Blade area; ii Ship speed; iii. Thrust power; iv Shaft power v. Torque (10)

Q9. Describe the effect of cavitaion on: i. The thrust and ordque; ii. The propeller blades B. A ship 150m long and 19m beam floats at a draught of 8m and last a block coefficient of 0.68 i) if the admicatry coefficient is 600 calculate the shaft power required at 18 knots; ii) If the speed is now increased to 21 knots, and within this speed range resistance varies as speed find the new shaft power.

Q5. In some circumstances electrical current may be induced into the shafting of rotating machinery.

a) state the problem that may be caused by this current.

b) Explain with aid of sketches, how currents may be avoided or reduced in the following instances:

(i) D.C machines

(ii) main shafting fitted with a bronze propeller

Q6.a) Define centre of buoyancy and show with the aid of sketches how a vessel which is Stable will return to the upright after being heeled by an external force (6)

b. An oil tanker of 17000 tonne displacement has its centre of gravity 1 m aft of midships and has 250 tonne of oil fuel in its forward deep tank 75 m from midships. This fuel is transferred to the after oil fuel bunker whose centre is 50 m from midships. 200 tonne of fuel from the after bunker is now burned. (10)

Calculate the new position of the centre of gravity:

(a) after the oil has been transferred

(b) after the oil has been used.

Q10. A. What are the factors which determine the synchronous speed of a motor?

B. A twelve-pole, three-phase, delta-connected alternator runs at 600 rev/min and supplies a balanced star-connected load. Each phase of the load is a coil of resistance 35 ohm and inductive reactance 25 ohm. The line terminal voltage of the alternator is 440V. Determine (a) frequency of supply, (b) current in each coil, (c) current in each phase of the alternator, (d) total power supplied to the load.

Q10. A. Describe how protection against short circuit is provided in a 3 phase induction motor circuit.
b) An eight – pole alternator running at a speed of 720rev/min supplies current to synchronous and induction motors with forty – eight poles. Calculate the frequency and speed of rotation of the motors if thr induction motor runs with 2 percent slip.

Q8. A. (i) What is direct-connected alternator? (3)

(ii)  How is a direct-connected exciter arranged in an alternator? (3)

B. A twelve-pole, three-phase, delta-connected alternator runs at 600 rev/min and supplies a balanced star-connected load. Each phase of the load is a coil of resistance 35 ohm and inductive reactance 25 ohm. The line terminal voltage of the alternator is 440V. Determine (a) frequency of supply, (b) current in each coil, (c) current in each phase of the alternator, (d) total power supplied to the load. (10)

Q9. A three-phase transformer has 560 turns on the primary and 42 turns on the secondary. the primary winding are connected to the line voltage of 6.6KV. Calculate the secondary line voltage when the transformer is connected a) Star-Detta b) Detta-Star

Q6. (a) Define TPC. Explain why TPC for a given draught will vary with the density of the water in which the ship floats (6)
(b) The pitch angle, measured at a distance of 2m from the centre of the boss, was found to be 21.5  Calculate the pitch of the propeller (10)

Q6. A vessel of 10000 t displacement burns 25 t of fuel per day when her speed is 12 Knots. Calculate the probable consumption of fuel over a voyage of 3000 nautical miles at a speed of 11 knots with a displacement of 11000 t. (16)

Q9. a) Explain what is meant by synchronous or resonant vibration (6)

b) A ship's speed is increased by 20% above normal for 8 hours, reduced by 10% below normal for 10 hours and for the remaining 6 hours of the day the speed is normal. Calculate the percentage variation in fuel consumption in that day from normal. (10)