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Q6. An alternator having 8 pole driven by 900 rpm Diesel engine supplies power to load of Synchronous motor having 24 poles and Induction motor of 8 poles and 2 % slip. A) Calculate the frequency and speed of Synchronous Motor. B) Calculate the frequency and Speed of Induction Motor

Q10. A 100 kW, 460 V shunt generator was run as a motor on no load at its rated voltage and speed. The total current taken was 9.8 A, including a shunt current of 2.7 A. The resistance of the armature circuit at normal working temperature was 0.11  Calculate the efficiencies at i. Full load; ii. Half load. (16)

Q8. A. What is meant by the Admiralty Coefficient and the Fuel Coefficient? (6)

B. A ship of 14900 tonne displacement has a shaft power of 4460 kW at 14.55 knots. The shaft power is reduced to 4120 kW and the fuel consumption at the same displacement is 541 kg/h. Calculate the fuel coefficient for the ship. (10)

Q7. A. Describe the stability requirements of a ship for dry-docking.

(b) A double bottom tank containing seawater is 6m long, 12m wide and 1m deep. The inlet pipe from the pump has its center 75mm above the outer bottom. The pump has a pressure of 70 kN/m2 and is left running indefinitely. calculate the load on the tank top:

 (i) If there is no outlet.

(ii) If the overflow pipe extends 5m above the tank top.

Q6. (a) Describe the relationship between frictional resistance and

(i) Ship’s speed;

(ii) the wetted area;

(iii) surface roughness;

(iv) The length of the vessel.

b) A ship 150m long and 8.5m draught has a rudder whose area is one sixtieth of the middle-line plane and diameter of stock 320mm. Calculate the maximum speed at which the vessel may travel if the maximum allowable stress is 70 MN/m? the centre of stock 0.9m from the centre of effort and the maximum rudder angle is 35 degrees. (10)

Q7. (a) The residuary resistance of a 1/25 scale model of a ship is 6.35 N when tested at 1.543 m/s in fresh water of density 1000 kg/m3. The frictional resistance of the ship at 12 knots in sea water of density 1025 kg/m3 is 145 kN. Frictional resistance can be assumed to vary with speed to the power 1.825. Calculate the effective power (naked) for the ship at the speed corresponding to the model test.

(b) The following additional data apply to the ship operating in service at the corresponding speed calculated in Q6 (a) with a propeller having a pitch of 4.6 m.

Appendage and weather allowance = 22%

Quasi-propulsive coefficient (QPC) = 0.7

Propeller speed = 1.75 rev/s

Taylor wake fraction = 0.32

Propeller thrust = 565 kN

Calculate EACH of the following:

(i) The torque delivered to the propeller; (ii) The propeller efficiency; (iii) The real slip ratio.

Q6. (a) Explain what is meant by floodable length. B. (i) Construct a graph from the following information:

(ii) From this graph find the TPC's at draft of 3.2m; and 4.3m; (iii) If the ship is floating at a mean draft of 4m, and then loads 50 tonnes of cargo, 10 tonnes of fresh water, and 25 tonnes of bunkers, whilst 45 tonnes of ballast are discharged, find the final mean draft.

Q7. A. Explain how increase of draught and of displacement influence rolling. (6)

B. A pontoon has a constant cross-section as shown in Fig. Given below the metacentre height is 2.5m. Find the height of the centre of gravity above the keel. (10)

Q6. A. What do you understand by reserve buoyancy what will happen if the lost buoyancy is greater than the reserve buoyancy.

B. A ship of 8100 tonne displacement floats upright in seawater. KG = 7.5m and GM = 0.45m A tank, whose centre of gravity is 0.5m above the keel and 4m from the centreline, contains 100 tonne of water ballast neglecting free face effect, calculate the angle of heel when the ballast is pumped out.

Q7. A) State briefly, the meaning of the expressions ‘star-connected’ as applied to three-phase a.c. practice. What is the ratio of the maximum line voltage to the maximum phase voltage in each case. (6)

B) Determine the line current taken by a 440V, three-phase, star-connected motor having an output of 45kW at 0.88(lagging) power factor and an efficiency of 93 per cent. (10)

7.a) Explain the term Angle of loll and state the dangers it poses to a vessel. What action to be taken to correct angle of loll. (6)

b. A ship of 22000 tonne displacement is 160 m long and MCTI cm 280tonne m, waterplane area 3060 m2 centre of buoyancy 1 m aft of midships and centre of flotation 4 m aft of midships. It floats in water of 1.007 t/ m3 at draughts of 8.15 m forward and 8.75 m aft.

Calculate the new draughts if the vessel moves into sea water of 1.026 t/ m2

Calculate the metacentric height of the vessel. (10)

8. When a ship is 800 nautical miles from port its speed is reduced by 20%, thereby reducing the daily fuel consumption by 42 tonne and arriving in port with 50 tonne on board. If the fuel consumption in t/h is given by the expression (0.136+0.001 V3) where V is the speed in knots, estimate:(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 increases in time for this latter period.