DieselShip's Online Content Library

Q7. (a) What are the various resistances acting against the motion of the ship? (6)

(b) A vessel of 10000 t displacement burns 25 t of fuel per day when her speed is 12 Knots. Calculate the probable consumption of fuel over a voyage of 3000 nautical miles at a speed of 11 knots with a displacement of 11000 t. (10)

Q7. A ship of 6400 t displacement is floating in salt water. The ship has to proceed to a berth where the density of the water is 1008 kg per cubic meter. Find how much cargo must be discharged if she is to remain at the salt water draft. (16)

Q6. a) State why cargo ships must have collision bulkheads. (6)

b) A double bottom tank is 1.2 m deep and has a sounding pipe extending 11 m above the tank top. The tank is filled with oil (rd 0.89) to the top of the sounding pipe. The double bottom floors are spaced 750 mm apart and are connected to the tank top by riveted angles, the rivets having a pitch of 7 diameters. If the maximum allowance stress in the rivets is 30 MN/m2, calculate the pressure in kN/m2 on the outer bottom and the diameter of the rivets. (10)

Q9. a) Explain Fleming's Right hand rule. (6)

b) A one-turn armature coil has an axial length of 0.4m and a diameter of 0.2m. It is rotated at a speed 500 rev/min in a field of uniform flux density of 1.2 T. Calculate the magnitude of the e.m.f. induced in the coil. (10)

Q9. A wooden ring having a mean diameter of 200 mm and a cross-sectional area of 400 mm2 is wound uniformly with a coil of 300 turns. If the current passed through the coil is 5 A calculate the value of flux produced in the coil. (16)

Q9. (a) Explain about non-linear resistors with some examples and illustration on how they differ from linear resistor. (6)

(b) A half-wave rectifier is used to supply 50V d.c. to a resistive load of 800Ω. The diode has a resistance of 25 Ω. Calculate a.c. voltage required. (10)

Q7. (a) Define Density, Relative Density (6)

(b) A bilge holding tank of 5 m length, 3 m width and 1.8 m depth has water of density 1.020 t/m3 up to a sounding of 1.3 m and oil of density 0.86 t/ m3 is floating on top of water up to an ullage of 0.3 m. Calculate the mass of water and oil in the tank. (10)

Q8. (a) Derive the formula for Admiralty Coefficient. (6)

(b) A ship travels 900 nautical miles at a speed of 12.5 knots and burns 150t of fuel over the voyage. Estimate the distance the ship could travel at a speed of 13.5 knots on 250t of fuel. (10)

Q4. a) What is a commutator? Discuss its rectifying action in detail. (6)
(b) Determine the line current taken by a 440 V, three-phase, star-connected motor having an output of 45 Kw at 0.88 (lagging) power factor and an efficiency of 93 per cent. (10)

Q6. a) What is back emf? Derive the relation for the back emf and the supplied voltage in terms of armature reactance. (6)

b) Two earth lamps at 120 V, 15 W are used on a 110 V distribution circuit. Due to damage to a motor, the resistance of the positive line is reduced to 10 ohm and that of the negative line to 5 ohm. Find the voltage across each lamp and the extra load on the generator due to the fault. (10)

Q5. With Reference to different types of transformers used onboard.

a) Discuss the basic principle of operation of a transformer (5)

b) Enumerate the different types of transformers used onboard also state their functions for which they are used. (5)

c) A 440/110 V single phase transformer supplies a load of 5kW at 0.8 power factor load. Calculate the primary and secondary currents. (Ignoring transformer power losses)? (6)

Q8. a) Show how the power that is transferred across the air gap of the three-phase induction motor is represented. Explain the terms. What portion of this is useful power? (6)

b) A 440 V load of 400 kW at 0.8 (lagging) power factor is jointly supplied by two alternators A and B. The kW load on A is 150 kW and the KVAr load on B is 150 KVAr (lagging). Determine the kW load on B, the KVAr load on A, the power factor of operation on each machine and the current loading of each machine. (10)