DieselShip's Online Content Library

Q10. 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) A box shaped vessel of length 100 metres and breadth 18 metres, floats in salt water on an even keel at 7.5 metres draft. KG = 4 metres. The ship has a continuous center line bulkhead which is watertight. Find the list if a compartment amidships, which is 15 metres long and is empty, is bilged on one side.

Q8. a) How do the leakage fluxes effect the operation of a transformer? How are they minimized? (6)
B. A 440 load of 400 KW at 0.8 (lagging) power factor is jointly supplied by two alternator 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)

Q6.A. What do you understand by reserve buoyancy what happen if the lost buoyancy is greater than the reserve buoyancy? (6)

B. A forward deep tank 12 m long extends from a longitudinal bulkhead to the ship’s side. The widths of the tank surface measured from the longitudinal bulkhead at regular intervals are 10, 9, 7, 4 and 1 m. Calculate the second moment of area of the tank surface about a longitudinal axis passing through its centroid. (10)

Q9. a) Sketch and describe the midship section of a bulk carrier, labelling the structural members. (6)

b) A vessel 40 m long has a constant cross-section in the form of a trapezoid 10 m wide at the top, 6 m wide at the bottom and 5 m deep. It floats in sea water at a draught of 4 m. Calculate its displacement. (10)

Q8. The 1/2 ordinates of a waterplane 120 m long are as follows: (16)

Section AP 1/2 | 1 | 1½ | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 8½ | 9 | 9½ | FP

½ ord 1.2 | 3.5 | 5.3 | 6.8 | 8.0 | 8.3 | 8.5 | 8.5 | 8.5 | 8.4 | 8.2 | 7.9 | 6.2 |3.5 |0m

Calculate: (16)

(a) Waterplane area

(b) Distance of centroid from midships.

Q8. a) What are the routine maintenance carried out on lead acid batteries? (6)

b) When a 10 Ω resistor is connected across a battery, the current is measured to be 0.18 A. If similarly tested with a 25 Ω resistor, the current is measured to be 0.08A. Find the e.m.f. of the battery and its internal resistance. Neglect the resistance of the ammeter used to measure the current. (10)

Q6. The resistors 5Ω, 7Ω, and 8Ω are connected in series across a voltage source of 10 V. Find the voltage drop across each resistor and also the total power consumed by the circuit. (16)

Q9. (a) Explain what is meant by phase difference between voltage and current values. (6)
(b) An inductance coil has a resistance of 19.5Ω and when connected to a 220V, 50Hz supply, the current passing is 10A. Find the inductance of the coil. (10)

Q9. a) Explain the effect of bilging a centreline compartment located away from amidships. (6)

B. A ship of 5000 tonne displacement has a double bottom tank 12m long. The ½ breadths of the top of the tank are 5, 4 and 2m respectively. The tank has a watertight centreline division. Calculate the free surface effect if the tank is partially full of fresh water on one side only. (10)

Q6. (a) Define angle of loll (6)

(b) A box barge 60 m long and 10m wide floats at an even keel draught of 4 m. It has a compartment amidships 12 m long. Calculate the new draught if this compartment is laid open to the sea when: (10)

(i) µ is 100%

(ii) µ is 85%

(iii) µ is 60%

Q6. a) How does change to frequency affect the operation of the transformer? What makes this ratio different from the ratio of transformer. (6)

b) The coils A and B are connected in series to 50 Hz mains. The current is 1 A and the voltage across each coil is measured to be 45 V and 70 V respectively. When the coils are connected in a d.c. supply, the current is also 1 A, but the voltages across the coils are now 20 V and 40 V respectively. Find the impedance, reactance and resistance of each coil, the total circuit impedance, the applied a.c. voltage and the power factor of the complete circuit. (10)

Q6. a) Describe Ingress protection rating and types of insulation. (6)

(b) A total load of 8000 kW at 0.8 power factor is supplied by two alternators in parallel. One alternator supplies 6000 kW at 0.9 power factor. Find the kVA rating of the other alternator and the power factor. (10)