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Q10. A box-shaped vessel is 20 m long and 10 m wide.  The weight of the vessel is uniformly distributed throughout the length and the draught is 2.5 m.  The vessel contains ten evenly spaced double bottom tanks, each having a depth of 1m. Draw the shear force diagrams:

With No.1 and No.10 tanks filled; With No.3 and No.8 tanks filled; With No.5 and No.6 tanks filled.

Which ballast condition is to be preferred from the point of view of strength?

Q7. (a) Describe how bulkheads are tested.

B. The following data are available for a twin-screw vessel:

V (Knots)
15
16
17
18
Epn (KW)
3000
3750
4700
5650
QPC
0.73
0.73
0.72
0.71
Calculate the service speed if the breaker power for each engine is 3500Kw. The transmission is 3% and the allowances for weather and appendages 30%.

Q6. a) Derive the expression for current and voltage relations between line and phase values in the star and delta cases. Draw vector diagram. (6)

b) A balanced delta connected load is connected to a 415V, 50 Hz Supply. If the per phase impedance of the load is (8+j12) ohm, calculate (i) the phase current of the load. (ii) line current (iii) power consumed by each phase.

Q9. 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 forward deep tank 12 m long extends from a longitudinal bulkhead to the ship’s side. The widths of the tank surface measured from the longitudinal bulkhead at regular intervals are 10, 9, 7, 4 and 1 m. Calculate the second moment of area of the tank surface about a longitudinal axis passing through its centroid. (10)

Q8. A ship 96 m long floating at 5 m fwd draft and 6.4 m aft draft. MCTC 180 tm, TPC 16. COF is 2 m abaft of midships. Find the location where a weight of 50 t should be placed so as to keep the aft draft constant. (16)

Q8. a) What is the effect of density of water on draught and TPC? (6)

b) A ship of 15000 t displacement floats at a draught of 7 m in water of RD 1.000. It is required to load the maximum amount of all to give the ship a draught of 7 m in sea water of RD 1.025. If the water plane area is 2150 m², Calculate the mass of oil required. (10)

Q6. a) State Ohm's Law. (3)

b) State the limitations of Ohm's Law. (3)

c) 3 resistors of value 2 Ω, 4 Ω and 8 Ω are connected in series across a supply of 42 V. Find the current taken from supply and voltage drop across each resistor. (10)

Q9. The following are the results of measurements taken at intervals over a half cycle of alternating voltage:

Time (t milliseconds)
0
0.45
0.95
1.5
2.1
2.5
3.1
3.9
4.5
5.0

Voltage (V volts)
0
20
36
40
37.5
33
32
31
20
0
Calculate the R.M.S value, average value and frequency of the wave. (16)

Q6. (a) What are the different types of DC motors? (6)

(b) A 10 H.P. 230 V shunt motor takes an armature current of 6A from 230 V mains at no load runs at 1200 r.p.m. The armature resistance is 0.25Ω. Determine speed and electromagnetic torque when the armature takes 36 amps with the same flux. (10)

Q8. a) Explain how excitation of the rotor is produced and supplied. (6)

b) A 75-kW, 400-V, 4-pole, 3-phase star connected synchronous motor has a resistance and synchronous reactance per phase of 0.04 Ohm and 0.4 Ohm respectively. Compute for full-load 0.8 p.f. lead the open circuit e.m.f. per phase and mechanical power developed. Assume an efficiency of 92.5%. (10)

Q6. (a) Describe the provisions of additional structural strength to withstand pounding. (6)

(b) A vessel travelling at 17 knots turns with a radius of 450 m when the rudder is put hard over. The centre of gravity is 7 m above the keel, the transverse metacentre 7.45 m above the keel and the centre of buoyancy 4 m above the keel. If the centripetal force is assumed to act at the centre of buoyancy, calculate the angle of heel when turning. The rudder force may be ignored. (10)

Q6. a) Describe the working of a single-phase full wave rectifier with a resistive load. Draw the load voltage and current waveforms. (8)

b) Diode half wave rectifier supply a resistive load of 100Ω from a 100 V ac r.m.s voltage source. The diode is a resistance of 5Ω during conduction state. Calculate

i) The DC output voltage

ii) DC average load current (8)