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Q8. 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.

Q8. A. Explain the reasons for fitting bulbous bow. B. When a ship is 800 nautical miles from port its speed is reduced by 20%, thereby reducing the daily fuel consumption by 42 tonne and arriving in port with 50 tonne on board. If the fuel consumption in t/h is given by the expression (0.136+0.001 V3) where V is the speed in knots, estimate: (i) The reduced consumption per day; (ii) The amount of fuel on board when the speed was reduced; (iii) The percentage decrease in consumption for the latter part of the voyage;

(iv) The percentage increases in time for this latter period.

Q6. Describe the movement of a ship with negative metacentric height B. A ship of 8000 tonne displacement has its centre of gravity 4.5m above the keel and transverse metacenter 5.0m above the keel when a rectangular tank 7.5m long and 15m wide contains seawater. A mass of 10 tonne is moved 12m across the deck. Calculate the angle of heel i. If there is free surface of water ii. If the water doesn’t completely fill the tank.

Q10. A. Explain the considerations which govern the size and shape of a rudder. B. A ship of 12000 tonne displacement has a rudder 15m2 in area, whose centre is 5m below the waterline.  The metacentric height of the ship is 0.3m and the centre of buoyancy is 3.3m below the waterline.  When travelling at 20 knots the rudder is turned through 30 .  Find the initial angle of heel if the force Fn perpendicular to the plane of the rudder is given by: Fa=577 Av2 sin  N, Allow 20% for the race effect.

Q8. A. Describe the ways in which an unstable ship can be made stable. B. When a mass of 25 tonnes is shifted 15m transversely across the deck of a ship of 8,000 tonnes displacement, it causes a deflection of 20cms in a plumb line 4m long. If the KM=7 m, calculate the KG

Q10. A) Describe measures which may be taken to improve the stability or trim of a damaged ship. (6)

B) A watertight bulkhead is 8m high and is supported by vertical stiffeners 700mm apart, connected at the tank top by brackets having 10 rivets 20mm diameter. The bulkhead is flooded to its top edge with sea water. Determine:

(a) Shearing force at top of stiffeners,

(b) Shear stress in the rivets,

(c) Position of zero shear. (10)

Q6. A ship 90 m long displaces 5200 tonne and floats at draughts of 4.95m forward and 5.35 m aft when in sea water of 1023 kg/m3. The water plane area is 1100m2, GML 95m, LCB 0.6m forward of midships and LCF 2.2m aft of midships. Calculate the new draughts when the vessel moves into fresh water of 1002 kg/m3

Q6. A. Describe the effect of cavitation’s on the propeller blades.

b) A ship has a constant cross-section in the form of a triangle which floats apex down in sea water. The ship is 85 m tong, 12 m wide at the deck and has a depth from keel to deck of 9 m. Draw the displacement curve using 1.25 m Intervals of draught from the keel to the 7 .5m waterline. From this curve obtain the Displacement in fresh water at a draught of 6.50 m. (10)

Q9. A. Describe how the force on the ship’s bottom and the GM vary when grounding takes place.

Q7. A box barge 45 m long and 15 m wide floats at a level keel draught of 2 m in sea water, the load being uniformly distributed over the full length. Two masses, each of 30 tonne, are loaded at 10 m from each end and 50 tonne is evenly distributed between them. Sketch the shear force diagram and give the maximum shear force.

Q10. The following data are available from the hydrostatic curves of a vessel.

Draught (m)
KB (m)

KM (m)
I (m4)
4.9
2.49

10.73
65250
5.2
2.61

10.79
68860
Calculate the TPC at a draught of 5.05m. (16)

Q6. 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 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: (10)

i. The propeller diameter.

ii. The shaft power.

iii the propeller efficiency.

iv. The thrust deduction factor.

Q6. (a) What is the significance of GM-GZ curve. (6)

(b) The pitch of a propeller is measured by means of a batten and cord. The horizontal ordinate is found to be 40 cm while the vertical ordinate 1.15 m at a distance of 2.6 m from the centre of the boss. Calculate the pitch of the propeller and the blade width at that point. (10)