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Q9. A propeller has a pitch ratio of 0.95. When turning at 120 rev/min the real slip is 30%, the wake fraction 0.28 and the ship speed 16 knots. The thrust is found to be 400 KN, the torque 270 KN-m and the QPC 0.67. Calculate:

i. The propeller diameter;

ii. The shaft power;

iii the propeller efficiency;

iv. The thrust deduction factor.

Q10. With reference to fixed pitch propellers:
a. Explain Propeller Slip and Propeller Thrust. (6)
b. The shaft power of a ship is 3000 KW, the ship’s speed V is 13.2 knot. Propeller rps is 1.27. Propeller pitch is 5.5m and the speed of advance is 11 Knots. Find:
i. Real Slip
ii. Wake fraction
iii. Propeller thrust, when its efficiency, η = 70% (10)

Q10. A. Explain the effects on stability when a tank is partially filled with liquid.

B. A ship of 11200 tonne displacement has a double bottom tank containing oil. Whose centre of gravity is 16.5m forward and 6.6m below the centre of gravity of the ship? When the oil is used the ship’s centre of gravity moves 380mm calculate - (i) The mass of oil used; (ii) The angle which the centre of gravity moves relative to the horizontal.

Q7. The values of effective power (naked hull) given in Table Q5 refer to a ship which is to have a service speed of 17.75 knots.

The following data also apply:
appendage allowance = 8%
weather allowance = 15%
quasi propulsive coefficient = 0.7
transmission losses = 3%
engine mechanical efficiency = 85%
ratio of service indicated power to installed machinery indicated power = 0.9

A. Determine the indicated power of the engine to be installed.

B. Determine the speed obtained if all the available power of the engine is used in EACH of the following:
(i) when the ship is running on acceptance trial in calm conditions;
(ii) when operating under actual service conditions.

Q8. A. List the variables which affect the force on a rudder. B. A propeller of 4m pitch has an efficiency of 67%.  When turning at 125 rev/min the real slip is 36% and the delivered power 2800Kw.Calculate the thrust of the propeller.

Q9. A. Describe briefly the inclining experiment and explain how the results are used. B. A ship of 8500 tonne displacement has a double bottom tank 11m wide extending for the full breadth of the ship, having a free surface of seawater. If the apparent loss in metacentric height due to slack water is 14cm, find the length of the tank.

Q6. a) Derive the expression for current and voltage relations between line and phase values in the star and delta cases. Draw vector diagram.

b) Three impedances Z=5+j4 are connected in the form of a delta to the three loads of a balanced 3-phase circuit. The line voltage is 120 Volts.

Find (a) The phase current, (b) Power factor, (c) The volt-ampere in the circuit.

10.A box-shaped barge of uniform construction is 80 m long, 12 m beam and has a light displacement of 888 tonne. The barge is loaded to a draught of 7 m in sea water of density 1025 kg/ m? with cargo evenly distributed. over two end compartment of equal length. The empty midship compartment extending to the full width and depth of the barge is bilged and the draught increases to 10m.

Determine:

(a) the length of the midship compartment.

(b) the longitudinal still water bending moment at midships:

(i) in the loaded intact condition

(ii) in the new bilged condition

Q10. A. Describe the relationship between frictional resistance and: (i)Ship speed; (ii) the wetted area; (iii) surface roughness; (iv) The length of the vessel.  B.A ship travels at 15 knots and has a QPC of 0.865 with a delivered power of 2600 KW. The apparent slip is 5% and the real ship is 28%Calculate the total resistance and the wake friction.

Q6.a) Explain the applications of PN junction diode. (6)

b) A full-wave, 1 -phase rectifier employs a double diode valve, the internal resistance of each element of which may be assumed constant at 500 W. The transformer r.m.s. secondary voltage from the centre-tap to each anode is 300 V and the load has a resistance of 2000 W.  Evaluate:-   (10)

(i) mean load current.

(ii) r.m.s. value of load current

(iii) the d.c. output power

(iv) the input power to the anode circuit

(v) the rectification efficiency

Q10. (A). Compare the effectiveness of a current limiting circuit breaker with that of a HRC fuse. (6)

B. Evaluate for a frequency of 15 kHz, the amplification and the phase difference between input and output signals of a voltage amplifier using a triode having an amplification factor of 48 and a mutual conductance of 1.2 m A/V with an anode-load resistant of 160 k𝛀. The output p.d. is fed by a coupling capacitor of negligible reactance to a subsequent circuit of resistance 480 k𝛀 and the total shunt capacitance is 90µ F. (10)

Q8. a) What is Prismatic Co-efficient (CP). Derive the formula CP =

, where

= Co-efficient of fineness and

= midship section area co-efficient. (6)
b) A watertight door is 1.2m high and 0.75m wide, with a 0.6m sill. The bulkhead is flooded with seawater to a depth of 3m on one side and 1.5m on the other side. Draw the load diagram and from it determine the resultant load and position of the centre of pressure on the door. (10)