Q6. A fine form vessel of length 120 m, having immersed transverse sections in the form of semi-circles, floats in sea water of density 1025 kg/m3.
The load waterplane is defined by half widths as shown in Table Q1.
Calculate EACH of the following:
(a) The load displacement;
(b) The height of the transverse metacenter above the center of buoyancy (BM);
(c) The block coefficient (Cb).
Q2. A box shaped vessel of length 100 m and breadth 12 m has a full breadth midship compartment 16 m long divided by a centerline watertight bulkhead to form equal tanks port and starboard.
The vessel is loaded to a draught of 6 m in sea water of density 1025 kg/m3 and in this condition the KG is 3.611 m and the midship compartment has a permeability of 80%.
The vessel is now bilged below the waterline on one side only at midships.
Calculate the resulting angle of heel.
Q3. The following particulars apply to a ship of 140 m length when floating in water of density 1025 kg/m3 at an even keel draught of 7 m.
Displacement = 14200 tonne
Centre Of gravity above the keel (KG)= 8.6 m
Centre Of buoyancy above the keel (KB) = 4.25 m
Waterplané area = 2049m2
Centre Of flotation from midships (LCF)= 4.5m aft
Second moment of area of the waterplane about a transverse axis through midships = 2.332 106 m4.
(a) Calculate the moment to change trim by 1 cm (MCT lcm). (6)
(b) The ship now has the following changes of loading:
143 tonne added with its lcg 10.5 m aft of midships
80 tonne removed with its lcg at midships
60 tonne moved 40 m aft
Calculate the new end draughts of the ship. (10)
Q5. A box shaped barge of length 70 m has a full mass of 420 tonne which is evenly distributed throughout its length. Bulkheads are located 5 m from the barge ends to form peak tanks which are empty.
The remainder of the barge is divided by two transverse bulkheads to form three holds of equal lengths. These holds are loaded with a total of 1680 tonne of level stowed bulk cargo, 480 tonne of which is loaded in the centre hold and the remainder is equally distributed in the other two holds.
Using graph paper, draw EACH of the following curves on a base of ship length:
(a) Weight and buoyancy curves; (5)
(b) Load curve; (3)
(c) Shear force curve; (4)
(d) Bending moment curve. (4)
Q7. The speed of a ship is reduced by 20% when 600 nautical miles from port, thereby reducing the daily fuel consumption by 42 tonne. The ship arrives in port with 60 tonne of fuel on board. The fuel consumption in tonne per hour is given by the expression:
C = 0.14 + 0.001 v3
where v is the speed in knots. Calculate EACH of the following:
(a) The reduced daily fuel consumption; (6)
(b) The amount of fuel on board when the speed was reduced; (4)
(c) The percentage decrease in fuel consumption for the reduced speed part of the voyage; (4)
(d) The percentage increase in time for this latter part of the voyage. (2)
Q7. (a) With respect to a ship’s propeller, explain the term thrust deduction.
(b) The following data were obtained during a ship’s acceptance trials:
Ship speed = 15.4 knots
Delivered power = 2500 kW
Effective power = 1730 kW
Thrust = 274 kN
Propeller efficiency = 64%
Apparent slip = 5%
(i) The thrust deduction fraction;
(ii) The Taylor wake fraction;
(iii) The true slip;
(iv) The hull efficiency.
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