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Q6. A vessel of constant rectangular cross section is 60 m long and 10 m wide, it floats at a level keel draught of 3 m and has a Centre of gravity 2.5 m above the keel. Determine the fore and aft draughts if an empty, full width, fore-end compartment 8 m long is opened to the sea. For simplicity, a permeability of 100 per cent may be assumed. (solve using lost buoyancy method)

Q9. A. Explain the effect on GM during the filing of a double – bottom tank, B. A ship of 8,000 tonnes displacement has KM 7.5m, and KG 7.0m.  A double bottom tank is 12 meters long 15 meters wide and 1 meter deep.  The tank is divided longitudinally at the centre line and both sides are full or small water. Calculate the list if one side is pumped on until it is half empty.

Q8. A. Explain why the amplitude of ship motion should be limited 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.

Q8: A box shaped barge of uniform construction is 32 metres long and displaces 352 tonnes when empty, is divided by transverse bulkheads into four equal compartments.  Cargo is loaded into each compartment and level stowed as follows: -

No. 1 hold – 192 tonnes                                               No.2 hold – 124 tonnes

No. 3 hold –272 tonnes                                                No.4 hold – 176 tonnes.

Construct load and shearing force diagram, before calculating the bending moments at the bulkheads and at the position of maximum value; hence draw the bending moment diagram.

Q7. a) Derive the Admiralty Coefficient formula and show how this may be modified to suit a fast ship. (6)

b) A 6m model of a ship has a wetted surface area of 7m2 and when towed in fresh water at

3knots has a total resistance of 35 N. Calculate the effective power of the ship, 120 m long, at its corresponding speed.

n=1.825. f from formula SCF=1.15 (10)

Q10. A. Write shorts notes on various types of DC Motors.

B. A 440V shunt motor takes an armature current of 30A at 700 rev/min. The armature resistance is 0.7ohm. If the flux is suddenly reduced by 20 per cent, to what value will the armature current rise momentarily? Assuming unchanged resisting torque to motion, what will be the new steady values of speed and armature current? Sketch graphs showing armature current and speed as functions of time during the transition from initial to final, steady-state conditions.

Q9. A. With reference to dynamical stability, describe the effect of an increase in wind pressure when a vessel is at its maximum angle of roll to windward.

(b) A ship of 5000 tonne displacement has three rectangular double bottom tanks A: 12m long and 16m wide; Tank B: 14m long and 15m wide; C 14m long and 16m wide.

calculate the free surface effect for any one tank and state in which order the tanks should be filled when making use of them for stability correction.

Q10. A. With reference to dynamical stability, describe the effect of an increase in wind pressure when a vessel is at its maximum angle of roll to windward.

b) A box shaped vessel of length 100 metres and breadth 18 metres, floats in salt water on an even keel at 7.5 metres draft. KG = 4 metres. The ship has a continuous center line bulkhead which is watertight. Find the list if a compartment amidships, which is 15 metres long and is empty, is bilged on one side.

Q8. a) How do the leakage fluxes effect the operation of a transformer? How are they minimized? (6)
B. A 440 load of 400 KW at 0.8 (lagging) power factor is jointly supplied by two alternator A and B. The KW load on A is 150 KW and the KVAr load on B is 150 KVAr (lagging). Determine the KW load on B, the KVAr load on A, the power factor of operation on each machine and the current loading of each machine.  (10)

Q9. A. List the precautions necessary before an inclining experiment is carried out.

B. The speed of a ship is increased to 18% above normal for 7.5 hours, and then reduced to 9% below normal for 10 hours. The speed is then reduced for the remainder of the day so that the consumption for the day is the normal amount. Find the percentage difference between the distance travelled in that day and the normal distance travelled per day.

Q9. a) Explain why an unstable ship is dangerous. (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)

Q7. A box barge 25 m long and 4 m wide floats in fresh water at a draught of 1.2 m and has an empty mid length compartment 5 m long. The bottom of the barge is lined with teak (rd 0.805) 120 mm thick. After grounding all the teak is torn off and the centre compartment laid open to the sea. Calculate the final draught. (16)