Q14. A ship of length 120m displaces 10650 tonne when floating at a draught of 7.2 m in sea water of density 1025 kgm3. The waterplane area is defined by half breadth as given in table.
When a mass of 10 tonne is moved a distance of 16 m across the deck, a deflection of 40mm is recorded on a pendulum of 8 m length.
The height of the centre of buoyancy above the keel (KB) may be determined suing morrish’s formula as given below.
Calculate the KG of the ship in the above condition.
Q2). A ship of length 150 m and breadth 20 m floats upright at a draught of 7.5 m in sea water of density of 1025 kg/m3 and the height of centre of gravity above the keel (KG) is 5.388 m.
Further hydrostatic data for this condition are as follows:
centre of buoyancy above the keel (KB) = 3.956 m
height of metacentre above the keel (KM) = 7.014 m
water plane area coefficient ( Cw) = 0.82
block coefficient ( Cb) = 0.72
In the above condition there is an empty rectangular wing tank 16 m long, 5 m wide and 5 m deep, adjacent to the hull and directly above a double bottom tank 1.2 m deep.
Calculate the angle to which the ship will heel when the tank is completely filled with fresh water of density 1000 kg/m3, assuming the ship to be wall sided over the change of draught. (16)
Q4. The hydrostatic particulars given in Table Q3 are for a ship of length 150 m when floating in water of density 1025 kg/m3.
The ship floats in water of density 1015 kg/m3 with draughts of 7.6 m aft and 6.8 m forward.
Calculate EACH of the following:
(a) The displacement;
(b) The longitudinal position of the ship’s centre of gravity.
Q6) A ship of 10000 tonne displacement has a rudder area of 25 m2. The ship has a KM of 6.9 m, KG of 6.3 m and the centre of lateral resistance is 3.9 m above the keel.
The maximum rudder angle is 35 degrees, and the centroid of the rudder is 2.3 m above the keel. The force generated normal to the plane of the rudder is given by:
F = 590 A v2 sinα (N)
where, A = rudder area ( m2)
v = ship speed (m⁄s)
α - rudder helm angle ( degrees)
Calculate EACH of the following, when the vessel is travelling at 22 knots.
(a) the angle and direction of heel due to the rudder force only, if it is put hard over to port; (8)
(b) the angle and direction of heel due to the combination of centrifugal force and rudder force when the rudder is hard over to port and the vessel turns in a circle of 800 m diameter. (8)
Q14. For a ship 120 m in length and 16 m breadth, the draught is 7 m in sea water of density 1025 kg/m and the block coefficient is 0.7. The effective power (naked) of the ship at a speed of 14 knots is estimated at 1900 kW, Wetted surface area (m2) = 2.57
Calculate the pull required to tow a similar model of length 4.8 m at the corresponding
Speed in fresh water of density 1000 kg/m3.
Note: The frictional coefficient for the model in fresh water is 1.703
The frictional coefficient for the ship in sea water is 1.421
Speed in m/s with index (n) for ship and model 1.825
Q15. The ship data in Table Q6 have been derived from the results of model experiments.
Determine EACH of the following using the data in Table Q6:
(a) The ship speed when the propeller is absorbing 5050 kW delivered power:
(b) The propeller speed (rev/see) given that the propeller has a diameter of 6 m with a
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