Q1. A ship 160 m in length has a load displacement of 20500 tonne and floats in water of density 1025 kg/m3. The load waterplane is defined by equally spaced half breadths as shown in Table Q1.
The following particulars are also available:
Centre of buoyancy above the keel (KB) = 4.264 m
Centre of gravity above the keel (KG) = 7.561 m
Centre of lateral resistance above the keel = 4.050 m
A rectangle tank, partially filled with oil of relative density 0.89 has overall dimensions of 10 m by 10 m, but is divided into two equal tanks by an oiltight longitudinal bulkhead.
Calculate EACH of the following:
(a) The effective metacentric height; (12)
(b) The angle to which the ship will heel when turning on a circular course of 400 m diameter at a speed of 16 knots. (4)
Q2. A vessel floating in sea water of density 1025 kg/m3 with a displacement of 6000 tonne has the following particulars:
Mean draught = 6 m
Centre of buoyancy above the keel (KB) = 3.305 m
Transverse metacentre above the centre of buoyancy (BM) =3.865 m
Transverse metacentric height (GM) = 0.670 m
Tonne per centimetre immersion (TPC) = 15
Calculate the mass to be added to the vessel at a Kg of 2 m to give a final transverse metacentric height of 1.0 m, assuming the vessel to be wall-sided over the affected range of draught. (16)
Q3. The following particulars apply to a ship of 125 m length when floating in water of density 1025 kg/m3 at an even keel draught of 6.425 m.
Displacement = 10850 tonne
Centre of gravity above the keel (KG) = 6.69 m
Centre of buoyancy above the keel (KB) = 3.57 m
Water plane area = 1756 m2
Centre of floatation from midship (LCF) = 2.5 m aft
Second moment of area of the waterplane about a transverse axis through midships = 1.526 10 6 m4
(a) Calculate the moment to change trim by 1 cm (MCT 1 cm) (4)
(b) The ship in the above condition now undergoes the following changes of loading.
50 tonne added with its LCG 27.5 m forward of midships.
230 tonne removed with its LCG 2 m aft of midships
120 tonne moved 46 m aft.
Calculate EACH of the following for the new condition:
(i) The new end draughts of the ship; (9)
(ii) The longitudinal position at which a mass of 188 tonne should be added to restore the ship to an even keel draught. (3)
Q4. A box shaped vessel 100 m long and 10 m wide floats at an even keel draught of 4 m in sea water of density 1025 kg/m3 with a KG of 5 m.
A full width, empty compartment has its after bulkhead 20 m forward of midships and its forward bulkhead 30 m forward of midships.
Calculate the end draughts of the vessel if this compartment is bilged. (16)
Q5. A uniformly constructed box shaped vessel of length 80 m and breadth 12 m has an even keel draught of 2 m when floating in the light condition in sea water of density 1025 kg/m3. The vessel has five holds of equal length and is to be loaded with 7000 tonne of cargo, with equal quantities in each of the centre and end holds, and the balance equally distributed in No.2 and No.4 holds. The cargo in all holds will be trimmed level.
(a) The maximum amount to be loaded in the centre and end holds in order that a maximum hogging bending moment amidships of 4000 tm will not be exceeded. (10)
(b) The resulting shear force at each of the bulkheads. (6)
Q7. A ship model of length 5.5 m has a wetted surface area of 4.65 m2 and is tested in water of density 1000 kg/m3. The test results give the values of residuary resistance for a range of model speeds as shown in table Q7.
(a) (i) Plot a curve of residuary resistance against speed for the model. (2)
(ii) Comment on the shape of the curve. (2)
(b) For a geometrically similar ship of length 132 m operating in sea water of density 1025 kg/m3 at service speed of 17 knots, the following data is applicable:
Appendage allowance = 6 %
Weather allowance = 12 %
Quasi-propulsive coefficient (QPC) = 0.71
Transmission losses = 3 %
Determine the shaft power required for the ship at its service speed. (12)
Note: frictional coefficient for the ship in sea water is 1.417
Speed is in m/s and index (n) for ship and model is 1.825
Q8. A model propeller of 0.3 m diameter and 0.25 m pitch is tested in fresh water of density 1000 kg/m3. At a speed of advance of 1.8 m/s and a rotational speed of 10.0 revs/s, the shaft torque is 12 Nm and the thrust developed is 260 N.
A geometrically similar ship’s propeller 5.4 m in diameter, is operating in sea water of density 1025 kg/m3 at corresponding linear and rotational speeds.
(a) For the ship’s propeller, calculate EACH of the following:
(i) Revolution per second. (1)
(ii) Speed of advance. (1)
(iii) Real slip. (3)
(iv) Delivery power. (3)
(v) Efficiency; (4)
(vi) Calculate the hull efficiency when the propeller is operating on a vessel at a Taylor wake fraction of 0.26 and a thrust deduction fraction of 0.22. (4)
Note: For geometrically similar propellers of corresponding speeds it can be assumed:
Linear speed is proportional to (diameter)1/2
Rotational speed is proportional to (diameter)-1/2
Thrust is proportional to (diameter)3
Torque is proportional to (diameter)4.
Q9. A watertight door in a bulkhead is 1.2 m high and 0.75 m wide, with a 0.6 m sill.
The bulkhead is flooded with sea water to a depth of 3 m on one side and 1.5 m on the other side.
(a) Draw the load diagram for the door. (8)
(b) From the load diagram drawn in Q9(a) determine:
(i) The resultant load. (3)
(ii) The position of the centre of pressure on the door. (5)
Username or email address *Required
Password *Required
Note: Entering wrong username in the login form will ban your IP address immediately. Entering wrong password multiple times will also ban your IP address temporarily.
Log in
Lost your password? Remember me
No account yet?
