DieselShip's Online Content Library

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 an inclining experiment on a new vessel? (6)

(b) When a mass of 6t 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)

Q8. a) Describe in detail the method used to measure the capacitance of a capacitor.(6)

b) A circuit has a resistance of 3R and an inductance of 0.01 H. The voltage across its ends is 60V and the frequency is 50Hz. Calculate (a) the impedance. (b) the power factor (c) the power absorbed.(10)

Q7. In the following circuit, E1 = 13 V, E2 = 19.5 V, R1 = 5 W, R2 = 7 W, R3 = 9 W. Find the current flowing through each resistor. (16)

Q7. An amplifier has an open-circuit voltage gain of 1000, an input resistance of 2000 Ω and an output resistance of 1.0 Ω. Determine the input signal voltage required to produce an output signal current of 0.5A in a 4.0Ω resistor connected across the output terminals. If the amplifier is then used with negative series voltage feedback so that one tenth of the output signal is fed back to the input, determine the input signal voltage to supply the same output signal current. (16)

Q9.a) Explain the principles of A.C. Motors starting and speed control, including the effect on efficiency. (6)

b) A 3-phase induction motor has a 4-pole, Y-connected stator winding. The motor runs on 50-Hz supply with 200V between lines. The motor resistance and standstill reactance per phase are 0.1 Ω and 0.9 Ω respectively. Calculate (a) the total torque at 4% slip (b) the maximum torque (c) the speed at maximum torque if the ratio of the rotor to stator turns is 0.67. Neglect stator impedance. (10)

Q7. (a) Show by means of diagrams how the center of gravity of the liquid in a partly filled tank moves during rolling. (6)

(b) A box barge is 15 m long, 6 m wide and floats in water of 1.016 t/m3 at a draught of 3 m. 150 tonne of cargo is now added. Calculate the load exerted by the water on the sides, ends and bottom. (10)