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Q1. A RO-RO ferry of length 80 m has a displacement of 3800 tonne in sea water of density 1025 kg/m3 with BM = 3.4 m. The breadth of the ship at the waterline, between sections 3 and 7 is constant at 13 m. To increase stability, sponsons, 1.8 m deep and of constant plan area are to be fitted as shown in Fig Q1.

The sponsons extend over the midships length between sections 3 and 7, with sponson widths as shown in Table Q1.

For the new condition, there is no change in draught and the load waterline is at mid-depth of the sponson. Calculate the increase in BM due to the sponsons.

Q3. Discuss the impact of technology and computers in relation to the following: A) In Ship Design B) In Ship Production C) In ship operation and maintenance.

Q2. The ‘wall sided formula’ gives an expression for righting lever (GZ) as follows:  GZ = sin θ (GM + ½ BM tan2 θ) (a) Derive an expression for the `angle of loll' of a ship which is initially unstable in still water, using the wall sided formula. (b) A box shaped vessel designed to carry timber, is 80 m long, 12 m wide and floats at a draught of 5 m in sea water of density 1025 kg/m3 with a KG of 4.815 m. A beam wind acts on the exposed area of the vessel causing it to heel to an angle of 15°. The heeling moment caused by the wind is given by the expression: Heeling moment = 0.85 A b v2 cos2 θ Nm

where:  A = exposed area = 627 m2 b = lever = 6.5 m      v = wind speed in m/s                                        θ = angle of heel in degrees.

Calculate the wind speed in knots, using the wall sided formula for GZ.

Q4. A ship of displacement 11000 tonne has a length 120 m, breadth 16 m, and even keel draught of 5.5 m in sea water of density 1025 kg/m3. The area of the waterplane is 1440 m2 and the second moment of area of the waterplane about a transverse axis through midships is 1.2 × 106 m4 with the LCF at midships. The ship has a full depth empty rectangular compartment of length 12 m and breadth 10 m.  The center of the compartment is on the centerline of the ship 40 m forward of midships.

Calculate the end draughts after the compartment is bilged.

Q5. A single screw vessel with a service speed of 15 knots is fitted with an unbalanced rectangular rudder 6 m deep and 4 m wide with an axis of rotation 0.2 m forward of the leading edge. At the maximum designed rudder angle of 35° the centre of effort is 30% of the rudder width from the leading edge. The force on the rudder normal to the plane of the rudder is given by the expression: Fn = 20.2 A v2α newtons

Where: A = rudder area (m2) v = ship speed (m/s)   α = rudder helm angle (degrees)

The maximum stress on the rudder stock is to be limited to 70 MN/m².

Calculate EACH of the following: (a) the minimum diameter of rudder stock required; (b) the percentage reduction in rudder stock diameter that would be achieved if the rudder was designed as a balanced rudder, with the axis of rotation 1.0 m aft of the leading edge.

Q6. Discuss the construction features of oil tanker with special attention to structure, capacity and architecture in view of the accidents and oil leaks.

Q7. The values of effective power (naked hull) given in Table Q5 refer to a ship which is to have a service speed of 17.75 knots.

The following data also apply:
appendage allowance = 8%
weather allowance = 15%
quasi propulsive coefficient = 0.7
transmission losses = 3%
engine mechanical efficiency = 85%
ratio of service indicated power to installed machinery indicated power = 0.9

A. Determine the indicated power of the engine to be installed.

B. Determine the speed obtained if all the available power of the engine is used in EACH of the following:
(i) when the ship is running on acceptance trial in calm conditions;
(ii) when operating under actual service conditions.

Q8. Explain the various resistances experienced by a ship. Describe the procedure for calculating the total resistance of ship.

Q9. With the aid of a demonstrating sketch explain the difference between International Load Line Marking and Subdivision Load line marking. How will you prepare your ship for a renewal Load Line Survey?