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Q7. An oil tanker 160m long and 22m beam floats at a draught of 9m in seawater. C_w is 0.865. The midships section is in the form of a rectangle with 1.2m radius at the bilges. A midships tank 10.5m long has twin longitudinal bulkheads and contains oil of 1.4 m³/t to a depth of 11.5m. The tank is holed to the sea for the whole of its transverse section.  Find the new draught.

Q10. A. List the precautions necessary before an inclining experiment is carried out.

B. A box shaped vessel, 50 metres long × 10 metres wide, floats in salt water on an even keel at a draft of 4 metres. A centre line longitudinal watertight bulkhead extends from end to end and for the full depth of the vessel. A compartment amidships on the starboard side is 15 metres long and contains cargo with permeability 30%. Calculate the list if this compartment is bilged. KG = 3 metres.

Q10. The daily fuel consumption of a ship at 17 knots is 42 tonne. Calculate the speed of the ship if the consumption is reduced to 28 tonne per day, and the specific consumption at the reduced speed is 18% more than at 17 knots.

Q6. The force acting normal to the centerline plane of a rudder is given by the expression:

Fn = 15.5 A v2 α newtons

Where, A = Rudder area (m2)

v = Ship speed (m/s)

α = Rudder helm angle (degrees)

A ship travelling at a speed of 20 knots has a rudder configuration as shown in Fig Q4. The center of effort for areas A1 and A2 are 32% of the width from their respective leading edges. The rudder angle is limited to 35º from the ship's centerline.

Calculate EACH of the following:

(a) The diameter of the rudder stock required for a maximum allowable stress of 77 MN/m2;

(b) The drag component of the rudder force when the rudder is put hard over at full speed.

Q9. (a) Describe the effects on centre of gravity of slack tanks. (b) A box-shaped vessel 100-meter-long x 20 meters wide X 12 meters deep is floating in salt water on an even keel at 6 meters’ draft. A forward compartment is 10 meters long, 12 meters wide and extends from the outer bottom to a watertight flat, 4 meters long 12 meters wide and extends from the outer bottom to a watertight flat, 4 meters above the keel. the compartment contains cargo of permeability 25%. find the new draft if this compartment is bilged.

Q6. A. Describe how the distribution of mass within the ship affects the rolling period B. A ship of 14000 tonne displacement is 125 m long and floats at draughts of 7.9 m forward and 8.5 m aft. The TPC is 19, GML 120 m and LCF 3 m forward of midships. It is required to bring the vessel to an even keel draught of 8.5m. Calculate the mass which should be added and the distance of the distance of the centre of the mass from midships.

Q10. The end bulkhead of the wing tank of an oil tanker has the following widths at 3m intervals commencing at the deck: 6.0, 6.0, 5.3, 3.6 and 0.6 m. Calculate the load on the bulkhead and the position of the centre of pressure if the tank is full of oil rd 0.8.

Q8. A. What are semiconductor devices? What are its advantages over thermionic devices?

What are semiconductor devices?

B. A 20kVA, 2000/220V, single-phase transformer has a primary resistance of 2.1Ω and a secondary resistance of 0.026Ω. The corresponding leakage reactance’s are 2.5Ω and 0.03Ω. Estimate the regulation at full load under power-factor conditions of.

(a) Unity;

(b) 0.5 (lagging) and

(c) 0.5 (leading).

Q9. a) Explain the concept of Dynamical stability. (6)

b) The wetted surface area of a container ship is 5946 m2, when travelling at its service speed, the effective power required is 11250 KW with frictional resistance 74% of the total resistance and specific fud consumption of 0.22 Kg/kW h. To conserve fuel, the ship speed is reduced by 10%, the daily fuel consumption is then found to be 83.0 tonne

Frictional coefficient in sea water is 1.432.

Speed in m/s with index (n) 1.825.

Propulsive coefficient may be. assumed constant at 0.6.

Determine

the service speed of the ship

the percentage increase in specific: fuel consumption when running at reduced speed. (10)

Q5. A. Explain why the GM must remain positive until the critical instant at which the ship takes the blocks overall.

B. A ship of displacement 10,010 tones has a container of 10t at KG = 7.5m. The container is shifted transversely. A pendulum of length 7.5m defects through 13.5m. GM of ship = 0.76m, KM = 6.7m. Find the distance through which the container shifted. Also find the new KG if the container is removed.

Q7. A. What is back emf? Derive the relation for the back emf and the supplied voltage in terms of armature resistance.

b) An 8kw, 230V, 1200 rpm d.c shunt motor has Ra = 0.7W. The field current is adjusted until, on no-load with a supply of 250V, the motor runs at 1250 rpm and draws armature current of 1.6 amps. A load torque is then applied to the motor shaft which causes la to raise to 40 A and the speed falls to 1150 rpm. Determine the reduction in the flux per pole due to the armature reaction.

Q8. a) Describe the process of correcting a negative GM. (6)

B. A ship 120 m long displaces 10500 tonne and has a wetted surface area of 3000 m2. At 15 knots the shaft power is 4100 kW, propulsive coefficient 0.6 and 55% of the thrust is available to overcome frictional resistance; calculate the shaft power required for a similar ship 140 m long at the corresponding speed.  = 0.42 and n = 1.825  (10)