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Q10. A. Explain how to distinguish between list and loll and describe how to return the ship to the upright in each case. B. A ship of 5000 tonne displacement has a double bottom tank 12m long. The ½ breadths of the top of the tank are 5, 4 and 2m respectively. The tank has a watertight centreline division. Calculate the free surface effect if the tank is partially full of fresh water on one side only.

Q7. A. Describe the effect of Cavitation on; The thrust and torque; The propeller blades B.A ship 120m long displaces 10500 tonne and has a wetted surface area of 3000m2. At 15 knots the shaft power is 4100KW, 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.   = 0.42 and n = 1.825

Q9. A. What is leakage flux as it applies to the iron-core transformer? How is it considered in the analysis of the transformer?

B. Three conductors fitted side by side in the stator of a salient-pole alternator. Each generates maximum voltage of 200V (sinusoidal). The angle subtended at the centre of the stator between adjacent conductors is 20 electrical degrees. If the three conductors are connected in series, find

(i) the r.m.s. value of the effective voltage and

(ii) the ‘breadth factor’. Using the theory that is the basis of this problem, give one reason why three-phase current has been introduced.

Q7. A. Explain how to distinguish between list and loll and describe how to return the ship to the upright in each case.  (B) A ship 90 long displaces 5200 tonne and floats at draughts of 4.95m forward and 5.35 m aft when in sea water of 1023 kg/m3. The water plane area is 1100m2, GML 95m, LCB 0.6m forward of midships and LCF 2.2m aft of midships. Calculate the new draughts when the vessel moves into fresh water of 1002 kg/m3

Q9. A. Describe the effects of changes in speed, rotor current and torque as load is applied to an induction motor. How does the motor adjust its stator current with changes in mechanical load?

B. A shunt motor runs at 900 rev/min when connected to a 440 V supply, the armature current being 60 A and armature resistance 0.4 ohm. At what speed will it run on a 220 V supply with an current of 40 A. Assume 60 percent reduction in flux for the 220 V connection.

Q8. A. Why is it important in a tender ship to keep the double bottom tanks pressed up?

B. The fuel consumption of a ship at 17 knots is 47 tonne/day. The speed is reduced and the consumption is reduced to 22 tonne/day. At the lower speed, however, the consumption per unit power is 13.2% greater than at 17 knots. Find the reduced speed and the percentage saving on a voyage of 3000 nautical miles.

Q9. A. What is Prismatic Co-efficient (CP). Derive the formula CP =

, where

= Co-efficient of fineness and

= midship section area co-efficient. (6)
B) The ½ ordinates of a water plane at 15m intervals, commencing from aft, are 1, 7, 10.5, 11, 11, 10.5, 8, 4 and 0m. Calculate:

(a). TPC;

(b). Distance of the centre of flotation from midships.

(c). Second moment of area of the water plane about a transverse axis through the centre of flotation.  (10)

Q8. a) Explain why the iron losses in a transformer are substantially independent of the load current. (6)

b) The equivalent circuit for a 200/400-V step-up transformer has the following parameters referred to the low-voltage side. (10)

Equivalent resistance = 0.15 W; Equivalent reactance = 0.37 W

Core-loss component resistance = 600 W; Magnetising reactance = 300 W

When the transformer is supplying a load at 10 A at a power factor if 0.8 lag, Calculate,

i) the primary current

ii) secondary terminal voltage.

Q9. (a) What are the effects of adding mass to draught and trim of a ship?
(b) A ship of 7000 t displacement has a water plane area of 1500 m2. In passing from sea water into river water of 1005 kg/m3 there is an increase in draught of 10 cm. Find the density of the sea water (10)

Q8. The centre of gravity of a ship of 5000 tonne displacement is 6 m above the keel and 1.5 m forward of midships. Calculate the new position of the centre of gravity if 500 tonne of cargo are placed in the t’ween decks 10 m above the keel and 36 m aft of midships. (16)

Q6. (a) How does a moving coil ammeter measure large current (6)

(b) A moving coil instrument with a coil resistance of 1.98Ω, produces full scale deflection from a current of 10mA. Determine the value of shunt required to extend the range up to 10A. (10)

Q8. a) Describe the means by which the magnetic flux associated with a conductor may be changed (6)

b) Find the generated e.m.f./conductor of a 6-pole d.c. generator having a magnetic flux/pole of 64m Wb and a speed of 1000 rev/min. If there are 468 conductors, connected in six parallel circuits, calculate the total generated e.m.f. of the machine. Find also the total power developed by the armature when the current in each conductor is 50 A. (10)