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Q8: A box shaped barge of uniform construction is 32 metres long and displaces 352 tonnes when empty, is divided by transverse bulkheads into four equal compartments.  Cargo is loaded into each compartment and level stowed as follows: -

No. 1 hold – 192 tonnes                                               No.2 hold – 124 tonnes

No. 3 hold –272 tonnes                                                No.4 hold – 176 tonnes.

Construct load and shearing force diagram, before calculating the bending moments at the bulkheads and at the position of maximum value; hence draw the bending moment diagram.

Q7. a) Derive the Admiralty Coefficient formula and show how this may be modified to suit a fast ship. (6)

b) A 6m model of a ship has a wetted surface area of 7m2 and when towed in fresh water at

3knots has a total resistance of 35 N. Calculate the effective power of the ship, 120 m long, at its corresponding speed.

n=1.825. f from formula SCF=1.15 (10)

Q10. A. Write shorts notes on various types of DC Motors.

B. A 440V shunt motor takes an armature current of 30A at 700 rev/min. The armature resistance is 0.7ohm. If the flux is suddenly reduced by 20 per cent, to what value will the armature current rise momentarily? Assuming unchanged resisting torque to motion, what will be the new steady values of speed and armature current? Sketch graphs showing armature current and speed as functions of time during the transition from initial to final, steady-state conditions.

Q9. 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 ship of 5000 tonne displacement has three rectangular double bottom tanks A: 12m long and 16m wide; Tank B: 14m long and 15m wide; C 14m long and 16m wide.

calculate the free surface effect for any one tank and state in which order the tanks should be filled when making use of them for stability correction.

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)

Q6.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 ½ ordinates of a waterplane 120 m long are as follows:

Section AP ½  1  1½  2  3  4  5  6  7  8  8½  9  9½  FP

½ord 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  0 m

Calculate:

a) waterplane area

b) distance of centroid from midships. (16)

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) Differentiate between resistance, induction and impedance in an a.c. circuit. (6)

b) A circuit is made up from resistors of value 2Ω, 4Ω, 5Ω and 10Ω connected in parallel. If the current is 8.6A, find the voltage drop across the arrangement and the current in each resistor. (10)