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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.

Q7. A. what is the effect on fuel consumption per unit time, if the ship’s speed is outside its operation range? B. The frictional resistance of a ship in fresh water at 3m/s is 11N/m2.  The ship has a wetted surface area of 2500m2 and the frictional resistance is 72% of the total resistance and varies as speed 1.92.  If the effective power is 1100Kw, calculate the speed of the ship.

Q6. A. Explain why the bilging of empty double-bottom or deep tanks below the waterline leads to an increase in GM.

B. the immersed cross-sectional area of a ship 120m long, commencing from aft are 2,40,79,100,103,104,104,103,97,58 and 0m^2 calculate - (i) Displacement; (ii) Longitudinal position of the centre of buoyancy.

Q10. A) Define torque and explain how it is developed in a D.C. Motor. Drive from first principles an expression for the torque developed in a D.C. Motor. (6)

(b) A diode valve, having the following characteristic is connected in series with a resistor of 10,000 ohm to a 240 V d.c. supply. If a resistor of 40,000 ohms is connected between the anode and cathode, determine the current through the diode.

Q6. A. With reference to dynamical stability, describe the effect of an increase in wind pressure when a vessel is at its maximum angle of roll to windward.

B. An oil tanker 160m long and 22m beam floats at a draught of 9m in seawater. Cw is 0.865. The midships section is in the form of a rectangle with 1.2m radius at the bilges. A midships tank 10.5m long has twin longitudinal bulkheads and contains oil of 1.4 m3/t to a depth of 11.5m. The tank is holed to the sea for the whole of its transverse section.  Find the new draught.

Q6. A box-shaped pontoon is 36 meters long, 4 meters wide and floats in salt water at drafts F-2.00m, A-4.00m. Find the new drafts if the pontoon now passes into fresh water.

Q9. A. Describe how the distribution of mass within the ship affects the rolling period;

B) The ½ ordinates of a water plane at 15m intervals, commencing from aft, are 1, 7, 10.5, 11, 11, 10.5, 8, 4 and 0m. Calculate:

(a). TPC;

(b). Distance of the centre of flotation from midships.

(c). Second moment of area of the water plane about a transverse axis through the centre of flotation.

Q9. A. What are the factors which determine the synchronous speed of a motor? (6)

B. A 72 KVA transformer supplies a heating and lighting load of 12 KW at unity power factor and a motor load of 70 kVA at 0.766 (lagging) power factor; Calculate the minimum rating of the power-factor improvement capacitors which must be connected in the circuit the ensure that the transformer does not become overloaded. (10)

Q7. a) Describe how water tightness is maintained where bulkheads are pierced by longitudinal beams or pipes. (6)

b) A ship of 15000 tonne displacement has an Admiralty Coefficient, based on shaft power, of 420. The mechanical efficiency of the machinery is 83%, shaft losses 6%, propeller efficiency 65% and QPC 0.71. At a particular speed the thrust power is 2550 Kw. (10)

Calculate: (i) Indicated power,         (ii) Effective power,           (iii) Ship speed.

Q6. (a) What is the purpose of conducting inclining experiment on a new vessel? (6)

(b) When a mass of 6 t is moved transversely through a certain distance on a ship of 4300t displacement, the deflection of an 11m pendulum is found to be 120 mm. The transverse meta-centre is 7.25 m above the keel and KG 5.46 m. Find the distance through which 6t was moved. (10)

Q6. The ratios of length, breadth and draught of a vessel are 18.5: 2.5: 1. The water plane area coefficient is 0.73 and the TPC is 0.77 more in sea water than in fresh water. Calculate the beam of the ship and TPC in fresh water. (16)

Q6. a) Explain, with reference to moments about the Centerline, how the list may be removed. (6)

b) A ship of 12,250 tonnes displacement, has KM=8 metres, KB=3.8 metres, KG=8 metres and is floating upright. Find the list if a weight of 2 tonnes, already on board, is shifted transversely through a horizontal distance of 12 metres assuming that the ship is wall-sided (10)