DieselShip's Online Content Library

Q1.  A ship 126 m floats at a draught of 7.5 m and in this condition the immersed cross sectional areas and waterplane areas are as given in Tables Q1(A) and Q1(B). The equivalent base area (Ab) is required because of the fineness of the bottom shell.

(a) the equivalent base area value Ab; (8)

(b) the longitudinal position of the centre of buoyancy from midships; (4)

(c) the vertical position of the centre Of buoyancy above the base. (4)

Q2. A ship of 25420 tonne displacement floating in sea water has 800 tonne of bunker fuel of density 895 kg / m³ in double bottom tanks which are pressed up full. In this condition the metacentric height is 0.25 m and the ordinates of the statical stability curve

Corresponding to this displacement are as shown in Table Q2.

 Table Q2

The oil is transferred to a deep tank 4.85 m long by 18.2 m wide, situated on the ship's centreline. The centre of gravity of the fuel after transfer is 6.8 m above the original centre Determine EACH Of the following for the new condition:

(a) the final effective metacentric height; (3)

(b) the angle to which the ship lists; (7)

(c) the dynamical stability at 200 angle Of heel.  (4)

Q4. A ship of displacement 6000 tonne in Sea water of density Of 1025 kg/m³ has a breadth of 20 m and a draught of 5.5 m.

The area of waterplane is 1500 m², KB is 3.2 m, KG is 4.8 m and the second moment of area of the waterplane about the centreline is 22000 m4.

A rectangular wing tank of length 10 m and breadth 4 m is situated above a double bottom of depth 1.1 m as shown in Fig Q4.

Calculate the angle of heel that would occur if the wing tank were bilged.  (16)

Q5. A box barge of length 50 m is of uniform construction and has a displacement of 600 tonne when empty.

The barge is divided by four transverse bulkheads to form five holds of equal length. Cargo is loaded as shown in Fig Q5, the cargo in each hold being uniformly distributed.

For this condition of loading:

(a) verify that the barge has an even keel draught; (2)

(b) draw to scale EACH Of the following:

(i) the load diagram; (6)

(ii) the shear force diagram; (5)

(c)using the diagrams drawn in Q5(b), determine the longitudinal position of the maximum bending moment. (3)

Q6) a) With the aid of an outline sketch explain EACH of the following:

(i) unbalanced rudder; (2)

(ii) semi-balanced rudder; (2)

(iii) balanced rudder. (2)

(b) State the principal advantage of fiiting a balanced rudder. (1)

(c) A ship travelling at full speed has its rudder put hard over to port, where it is held until the ship completes a full turning circle.

Describe, how the ship will heel from the upright condition during the manoeuvre by illustrating the moments produced by the forces acting on the ship and the rudder. (9)

Q7. A ship 137 m long displaces 13716 tonne. The shaft power required to maintain a speed of 15 knots is 4847 kW, and the propulsive coefficient based upon shaft power is 0.67.

wetted surface area = 2.58

propulsive coefficient = ep/ sp

Values of the Froude friction coefficient for Froude’s Formula are given in Fig Q7, with speed in m/s and speed index (n) =1.825

Calculate the shaft power for a geometrically similar ship which has a displacement of 18288 tonne and which has the same propulsive coefficient as the smaller ship, and is run at the corresponding speed. (16)

Q8. The following data, shown in Table apply to a ship travelling at 17 knots

Calculate EACH of the following:

(a) the apparent slip ratio;  (4)

(b) the propeller diameter;  (2)

(c) the propeller efficiency;  (4)

(d) the thrust deduction fraction;  (4)

(e) the specific fuel consumption.  (2)

Q9. An end bulkhead of an upper hopper tank is shown in Fig Q9.

The tank is tested by filling with fresh water of density I000 kg/m³ through a fitting pipe to a head of 2.5 m above the upper deck.

Calculate EACH of the following:

(a) the load on the bulkhead; (8)

(b) the distance to the centre of pressure from the upper deck.  (8)