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Q3. Sketch and describe a boiler water level controller of the float operated type. State the reasons for having this mechanism on the boiler and using this controller and boiler for analogy explain the following terms.

A. Detecting element

B. Servo motor

C. Desired Value

Q7. Discuss the causes of corrosion and the means by which corrosion of the following may be limited by manufacturers and ship’s personnel respectively:

A. Internal and External surfaces of auxiliary steam lines;

B. External surfaces of auxiliary boilers;

C. Water boxes of seawater coolers and condensers;

D. Main sea water inlet pipes.

Q8. A. Explain the action of EACH of the following metallurgical mechanism:

(i) Creep;          (ii) Brinelling;   (iii) Fretting;     (iv) Fretting corrosion;

B .State, with reasons, where EACH of the mechanisms in occur in ship propulsion System.

Q7. A rudder of a vessel requires extensive welding repairs and as Second Engineer you are requested to supervise the repairs.

A.  Suggest a suitable type of welding process;

B. State, with reasons, FOUR common welding defects.

C. State what tests may be carried out before returning the rudder to service.

Q6. With regards to main transmission shaft flange coupling arrangements:

A. Sketch a hollow type coupling bolt and the hydraulic head/nut and loading rod which are used to fit it.

B. Describe how the bolt is fitted.

C. State the advantage of the hollow coupling bolt as compared to the traditional type of coupling bolt.

Q9. Describe with a sketch a pneumatic relay and show how feedback can be achieved when such a relay is used in conjunction with a flapper mechanism. (16)

Q7. A. Explain why centrifugal pumps cannot handle air or vapours to effect priming yet turbo- blowers operating on the same principle can.

B. If a vessel is fully laden, how may it be ascertained that the fire pump priming arrangements would operate satisfactorily in the ballast condition.

C. Explain a suitable method of priming suitable for a centrifugal pump.

Q5. A. Describe a transverse bow thrust unit using CPP, mention how it should be made to support and how the strength of thrust and reverse thrust are achieved;

B. State with reasons, a suitable prime mover for the controllable pitch propeller;

C. State whether the thrust unit delivers a relatively low pressure head with high volume output or high pressure head with low volume output.

Q4. Reverse osmosis is the modern alternative for shipboard production of drinking water.

(a) Describe using simple diagrams if necessary, the principle of reverse osmosis. (8)

(b) Sketch a line diagram showing a single pass system for producing fresh water from sea water and describe the system. (8)