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Q9. A. Explain the effect of bilging a centreline compartment located away from amidships.

b) A ship of 4000 tonne displacement has a mass of 50 tonne on board, on the centre line of the tank top. A derrick, whose head is 18 m above the CG of the mass, is used to lift it. Find the shift in the ship's centre of gravity from its original position when the mass is

(i) lifted Just clear of the tank top

(ii) raised to the derrick head

(iii) placed on the deck 12 m above the tank top. (10)

Q9. a) What is the operational impedance of an R.C. Circuit? Describe its usefulness. (6)
B. A ring-main, 900m long, is supplied at a point A at a p.d. of 220V. At a point B, 240m from A, a load of 45A is drawn from the main, and at a point C, 580m from A, measured in the some direction, a load of 78A is taken from the main. If the resistance of the main (lead and return) is 0.25 ohm per kilometre, calculate the current which will flow in each direction round the main from the supply point A and the potential difference across the main, at the load where it is lowest. (10)

Q7. A. Explain how to distinguish between list and loll and describe how to return the ship to the upright in each case. (6)

B. A ship 120m long has a light displacement of 4000 tonne and LCG in this condition 2.5m aft of midships.  (10)

The following items are then added:

Cargo    10000 tonne      LCG 3.0 m          forward of midships

Fuel      1500 tonne        LCG 2.0 m          aft of midships

Water    400 tonne          LCG 8.0 m          aft of midships

Stores   100 tonne          LCG 10.0m         forward of midships

Using the following hydrostatic data, calculate the final draughts:

Draught (m) --- Displacement (t) --- MCTI cm (tm) --- LCB from midships (m) --- LCF from midships (m)
8.50 ---------- 16650 -------------- 183 ------------ 1.94 F ------------------ 1.20A
8.00 ---------- 15350 -------------- 175 ------------ 2.10 F ------------------ 0.60F

Q9. A hopper barge of box form 50 m long and 10 m wide floats at a draught of 2 m in seawater when the hopper, which is 15 m long and 5 m wide, is loaded with mud having relative density twice that of the seawater, to the level of the waterline. Doors in the bottom of the hopper are now opened allowing the mud to be discharged. Calculate the new draught. (16)

Q6. a) What are the various resistances acting against the motion of the ship? (6)

b) A vessel uses 300 t of fuel on a voyage of 3000 nautical miles at a speed of 12 knots when her displacement is 10000 t. Estimate the fuel required for an estimated voyage of 1500 nautical miles at a speed of 15 knots and displacement of 14000 t. (10)

Q9. a) Name the various types of capacitors? (6)

b) A 500W, 100V bulb is to be connected across 250V, 50Hz mains. Find the value of the capacitor required to be connected in series. (10)

Q7. Ten thousand cubic millimeters of copper are

a) Drawn into a wire 100 metres long,

b) Rolled into a square sheet of 100 mm side. Find the resistance of the wire and the resistance between opposite faces of the plate, if the resistance of the copper is 17 μΩmm or 1.7 x 10-8 ohms-metres. (16)

Q9. a) Differentiate between resistance, induction and impedance in an a.c. circuit. (6)

b) A circuit is made up from resistors of value 2Ω, 4Ω, 5Ω and 10Ω connected in parallel. If the current is 8.6A, find the voltage drop across the arrangement and the current in each resistor. (10)

Q9. a) Explain the effect of bilging a centreline compartment located away from amidships. (6)

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. (10)

Q6. (a) Define angle of loll (6)

(b) A box barge 60 m long and 10m wide floats at an even keel draught of 4 m. It has a compartment amidships 12 m long. Calculate the new draught if this compartment is laid open to the sea when: (10)

(i) µ is 100%

(ii) µ is 85%

(iii) µ is 60%

Q6. a) How does change to frequency affect the operation of the transformer? What makes this ratio different from the ratio of transformer. (6)

b) The coils A and B are connected in series to 50 Hz mains. The current is 1 A and the voltage across each coil is measured to be 45 V and 70 V respectively. When the coils are connected in a d.c. supply, the current is also 1 A, but the voltages across the coils are now 20 V and 40 V respectively. Find the impedance, reactance and resistance of each coil, the total circuit impedance, the applied a.c. voltage and the power factor of the complete circuit. (10)

Q6. a) Describe International protection rating and types of insulation. (6)

(b) A total load of 8000 kW at 0.8 power factor is supplied by two alternators in parallel. One alternator supplies 6000 kW at 0.9 power factor. Find the kVA rating of the other alternator and the power factor. (10)