2nds Questions

Chapter

Description

01.

Filtration, Pollution, Sewage

02.

Refrigeration

03.

Heat Exchangers

04.

Systems, Pumps, etc.

05.

Rudders, Steering Gears

06.

Shafting and Bearings

07.

Control

08.

Materials

09.

Lubricating Oils

10.

Fuel Oils

11.

Feed Water, etc.

12.

Fires and Explosions

13.

Insulation Resistance

14.

Electrical Systems, Batteries, etc.

15.

Electrical Machines

16.

Switchboards, etc.

17.

Stablisers, Rudders

18.

Propellors, thrusters, etc

19.

Corrosion, Fouling

20.

Systems, Safety

21.

General Ship Construction, Drydock.

22.

Compressors

23.

OW.T. Doors

24.

General

FILTRATION, POLLUTION, SEWAGE

2. (i) Suggest with reasons whether static filters should be cleaned : ( 7 marks)

At regular intervals of time,

Or after a prescribed number of operational hours,

Or when filter condition warrants it.

(ii) State with reasons how static filtration can be improved n practice. (3 marks)

3. Give reasons why each of following conditions can result in oil being discharged with the water from a static oily water separator :

(i) High oil density, (3 marks)

(ii) Low mixture temperatures, ( 3 marks)

(iii) High pumping rate, (2 marks)

(iv) Oil/water interface below test cocks ( 2 marks)

4. (i) Draw a line diagram of a zero discharge (self contained) sewage system, labelling the principal items and showing the direction of flow in all lines. (4 marks)

Describe how the effluent is :

(ii) Collected and stored, (3 marks)

(iii) Treated for discharge ashore or destruction aboard (3 marks)

5. Give reasons why each of the following conditions in oily water separators can result in oil carry over with the water :

(i) High throughput of mixture (2 marks)

(ii) Low temperature of mixture, ( 2 marks)

(iii) Considerable oil content in mixture, (2 marks)

(iv) High density of oil. ( 2 marks)

(v) Outline the value of test cocks. ( 2 marks)

6. Give reasons why each of the following conditions in centrifuges can result in oil carry-over with the water :

(i) High throughput of mixture, (2 marks)

(ii) Low temperature of mixture, ( 2 marks)

(iii) Considerable sediment suspension in mixture, ( 2 marks)

(iv) Considerable oil content in mixture, (2 marks)

(v) Bowl speed below designed speed. ( 2 marks)

7. (i) Sketch the bowl of an automatic self cleaning centrifuge, labelling the principal components and showing the direction of flow of all fluids. (4 marks)

(ii) State with reasons what protection is provided against malfunction. ( 3 marks)

(iii) State why air filters are fitted to air compressors and diesel engines. (3 marks)

(iv) State why oil filters are normally fitted between fuel and lubricating oil tanks and their respective pumps. ( 3 marks)

8. Explain how the following conditions contribute to the satisfactory performance of oil centrifuges :

(i) Negligible clutch slip in bowl dirve, ( 2 marks)

(ii) Reasonable internal cleanliness of bowl, ( 2 marks)

(iii) Low rate of feed of contaminated oil, ( 2 marks)

(iv) Contaminated oil preheated prior to centrifuging, ( 2 marks)

(v) Contaminated oil allowed to stand for an appreciable time in settling tank prior to centrifuging. ( 2 marks)

9. Explain how the following conditions contribute to the satisfactory performance of oil centrifuges :

(i) Negligible clutch slip in bowl drive, ( 2 marks)

(ii) Reasonable internal cleanliness of bowl, ( 2 marks)

(iii) Low rate of feed of contaminated oil, ( 2 marks)

(iv) Contaminated oil preheated prior to centrifuging( 2 marks),

(v) Contaminated oil allowed to stand for an appreciable time in settling tank prior to centrifuging. ( 2 marks)

10. With reference to oil centrifuges state why :

(i) They are used for oil contaminated by water, but are not used for water contaminated by oil. (3 marks)

(ii) They do not render static filters redundant, ( 3 marks)

(iii) Severe bowl vibration may occur in service, ( 2 marks)

(iv) Bowl may spin at a reduced speed. ( 2 marks)

11 Sketch a static oily water separator intended to handle large quantities of heavily contaminated water, labelling the principal components, showing the internal arrangement of subdivision, baffles and fittings, and indicating the direction of fluid flow in all parts. (4 marks)

Describe how it operates. (4 marks)

12 Give two reasons why oil might be carried over with the water. (2 marks)

Draw a line diagram of a zero discharge sewage system in which the water is recirculated and the solids processed for disposal, labelling the principal components and showing the direction of flow in all lines. (4 marks)

Describe how the system operates. (4 marks)

13 Give reasons why this system might be considered superior to that in which the sterile water is discharged overboard at sea. (2 marks)

Sketch a 'self cleaning' filter as commonly incorporated in main lubrication systems, showing in detail the filter pack. (3 marks)

Describe how foreign matter in the oil is captured. ( 2 marks)

Identify with reasons that part of th filter mechanism which basically determines the maximum size of the suspended solids arrested. ( 2 marks)

Define the indications that such a filter requires cleaning. ( 1 mark)

Give two reasons why heavily foulded filters require immediate attention. ( 2 marks)

14 Give reasons why each of the following conditions can result in oil being carried over with the water discharge from lubricating oil centrifuges :

(i) high throughput of mixture ( 3 marks)

(ii) abnormally high temperature of mixture (3 marks)

(iii) appreciable accumulation of solids in bowl (4 marks)

15. (i) Give reasons why magnetic filters normally complement static filters in main lubricating oil systems where bearing surfaces are of non- ferrous nature.

(ii) Identify the source and nature of deposits found in such filters.

(iii) Explain how the quantity and quality of the collected deposits give a good indication of conditions prevailing in the main machinery. ( 3 marks)

(iv) State why centrifuges do not render magnetic filters redundant. ( 1 mark)

16 With reference to oil centrifuges :

(i) Differentiate between the roles of purifiers and classifiers, ( 3 marks)

(ii) Explain how fluids of differing characteristics and degrees of contamination can be handled individually by one machine. ( 4 marks)

(iii) Give reasons why settling tanks do not make the use of centrifuges redundant. (3 marks)

17. (i) Give reasons why magnetic filters normally complement static filters in main lubricating oil systems where bearing surfaces are of a non-ferrous nature. ( 3 marks)

(ii) Identify the source and nature of deposits found in such filters. ( 3 marks)

(iii) Explain how the quantity and quality of the collected deposits give a good indication of conditions prevailing in the main machinery. (3 marks)

(iv) State why centrifuges do not render magnetic filters redundant. ( 1 mark)

18. With reference to static oily water separators :

(i) Explain how efficiency is related to mass flow rate, ( 2 marks)

(ii) Define the contribution of coagulators to efficiency, ( 2 marks)

(iii) Explain how internal baffles and subdivisional screens affect separation, ( 2 marks)

(iv) Define the value of air release values, ( 2 marks)

(v) Give reasons why rotary positive displacement pumps are preferable for supply duties rather than centrifugal pumps. ( 2 marks)

19. (i) Draw a line diagram of a sewage system in which the holding tank is small when compared to the amount of sewage ( 4 marks)

(ii) Describe how the system operates ( 4 marks)

(iii) State why the holding tank is small compared to other systems ( 2 marks)

20. (a) Draw a line diagram of a biological sewage system in which only sterile water is discharged overboard at sea, labelling the principle items and showing the direction of flow in all lines. ( 4 marks)

(b) Describe briefly how it operates. ( 4 marks)

(c) Define its principal disadvantages. ( 2 marks)

21. (a) Draw a line diagram of a biological sewage system in which only sterile water is discharged overboard at sea, labelling the principle items and showing th direction of flow in all lines. ( 4 marks)

(b) Explain how it operates. ( 3 marks)

(c) State three advantages it has over other sewage systems ( 3 marks)

22. Give reasons why each of the following conditions can result in oil being discharged with the water from a static oily water separator :

(a) Density of oil approaching that of water, ( 3 marks)

(b) Low mixture temperatures, ( 3 marks)

(c) High pumping rate, ( 2 marks)

(d) Oil/water interface below test cocks. ( 2 marks)

23. With reference to centrifugal oil fuel purifiers explain : -

(a) Why the drive often incorporates a clutch, ( 3 marks)

(b) The possible causes of vibration, ( 2 marks)

(c) How the unit can be designed to be self cleaning and how this operation is made to be automatic ( 5 marks)

24. (a) Why are most centrifuges fitted with centrifugal clutched, ( 3 marks)

(b) Explain what part the gravity ring plays in separation. ( 4 marks)

(c) If on starting the centrifuge vibrates excessively what action should the operator take, and comment about the likely causes of the vibration. ( 3 marks)

25. (a) Sketch a static oily water separator, labelling all its important internal parts, ( 4 marks)

(b) Describe how it is intended to work. ( 3 marks)

(c) Explain the circumstances which would probably have the effect of reducing the separator efficiency. ( 3 marks)

26. (a) Explain how a discharge mechanism of a self-cleaning purifier bowl works.

(b) Comment on the problems that might occur if the self-cleaning system mal-functions. ( 4 marks)


REFRIGERATION

2. With reference to refrigeration plants state why :

(i) Refrigerant leakage imposes additional loading on the plant, ( 2 marks)

(ii) Excessive opening of the expansion regulator can cause severe icing at compressor suction, ( 3 marks)

(iii) Brine batteries need systematic 'de-frosting' to maintain effectiveness, ( 2 marks)

(iv) Although refrigerant contamination by oil is serious, water contamination is even more serious. ( 3 marks)

3. With reference to accommodation air conditioning plants explain why :

(i) Compartment temperatures tend to rise, ( 2 marks)

(ii) This temperature rise varies considerably from space to space, ( 2 marks)

(iii) Mechanical ventilation with air heating facilities is inadequate for comfort in ships operating between polar and equatorial ( 3 marks)

(iv) Air changes and compensation for air loss is essential. ( 3 marks)

4. (i) Draw a line diagram of an accommodation air conditioning plant labelling the principal items and showing the direction of air flow. ( 4 marks)

State how:

(ii) Accommodation air temperature is controlled, ( 2 marks)

(iii) Humidity is controlled within prescribed comfort limits, ( 2 marks)

(iv) Such an installation can contribute to the efficiency of ship's main plant. ( 2 marks)

5. (i) Sketch in diagrammatic form, a refrigeration unit operating on the vapour compression system ( 3 marks)

(ii) Describe how it operates and how adjustments can be made to its operating temperature. ( 3 marks)

(iii) What effect will the following have on its operation (a) high ambient temperature (b) gradual loss of gas, and (c) dirty heat exchanger. ( 4 marks)

6. Suggest with reasons the most likely cause of the trouble if the suction to a multicylinder refrigerant compressor is subject to considerable icing under the following simultaneously prevailing conditions :

(a) Compressor in good condition and running at normal speed, ( 3 marks)

(b) No detectable loss of refrigerant, ( 3 marks)

(c) No detectable loss of refrigerant, ( 2 marks)

(d) Brine temperature rising. ( 2 marks)

7. State with reasons why the following courses of action might be advisable if the temperature of the ship's cold lockers rises steadily although the refrigerant compressor runs continuously :

(i) 'de ice' exaporater, ( 2 marks )

(ii) 'top up' with refrigerant, ( 3 marks)

(iii) Clean both sides of condenser, ( 2 marks)

(iv) Overhaul compressor ( 3 marks)

8. Give reasons why each of the following conditions can result in excessive running of refrigerant compressors :

(i) High sea water temperature, ( 2 marks)

(ii) High atmospheric air temperature, ( 2 marks)

(iii) Leak in evaporator, ( 2 marks)

(iv) Air in refrigerant circuit, ( 2 marks )

(v) Fouling on water side of condenser, ( 2 marks)

9. With reference to refrigeration plants state how :

(a) Very low evaporator temperatures are achieved, ( 2 marks)

(b) Automatic expansion valves indirect expansion plants are adjusted, ( 2 marks)

(c) Compressors are protected against appreciable "carry over" of liquid refrigerant. ( 2 marks)

(d) Air in the system is detected, ( 2 marks)

(e) Over charge of refrigerant is indicated. ( 2 marks)

10. Briefly describe how in main refrigeration plants :

(a) Sea temperature can restrict plant operation

(b) The limitations in ( a) are overcome,

(c) Short cycling occurs,

(d) Short cycling is avoided ( 10 marks)

11. (a) Draw a line diagram of a cargo refrigeration plant provided for the carriage of refrigerated containers in one hold only, labelling the principal items and showing the directon of fluid flow in all lines and ducts, ( 2 marks)

(b) Explain how heat is extracted from the container contents and transferred to the condenser coolant,. ( 4 marks)

12. With reference to refrigeration plants define :

(a) Indications of refrigerant leakage, ( 3 marks)

(b) Steps to locate leak, ( 2 marks)

(c) Steps in refrigerant replenishment ( 3 marks)

(d) Indications of full charge restoration ( 2 marks)

13. (a) Explain the following terms with reference to air conditioning :-

(i) Wet bulb temperature

(ii) Dew point temperature

(iii) Relative humidity ( 3 marks)

(b) Itemize the preventive maintenance you would expect to be necessary on the automatic controls of an air conditioning plant with which you are familiar.

14. Sketch a section through the crankcase and pair of cylinders of a vee type refrigerant compressor indicating the direction of flow of refrigerant. ( 4 marks)

State why a compressor my 'short cycle' and how this condition is correct. ( 3 marks)

State why excessive 'icing up' may occur and how the compressor is protected. ( 3 marks)

15. In practice there is usually more than one possibility for nay particular symptom in a refrigeration plant. Give two reasons for each of the following in a freon system :

(a) High head pressure. ( 2 marks)

(b) Low head pressure. ( 2 marks)

(c) Compressor runs continuously ( 2 marks)

(d) Compressor runs nosily ( 2 marks)

(e) Compressor will not start (fuses have not blown and compressor will rotate). ( 2 marks)

Heat Exchangers

2. (i) Sketch a multi plate heat exchanger, labelling the principal components and showing the direction of fluid flow in all passages ( 5 marks)

(iii) Give three reasons tor plate relief putttern. ( 3 marks)

(iii) Explain why gasket thickness is critical. ( 2 marks)

1) With reference to multi tubular heat exchangers state why:

a) Fresh water is generally preferred to sea water as a coolant.

b) Lubricating oil is generally maintained at a marginally positive head relative to the coolant.

c) Contra flow and multi pass arrangements tend to improve hear transfer rates for a given surface area.

d) Intermediate diaphragm plates make a useful contribution to tube life.

2) (a) Sketch a multi plate heat exchanger, libeling the principal components and showing the direction of fluid flow in all passages.

(b) give three reasons for pleat relief pattern.

(c) explain why gasket thickness in critical.

3) With reference to multi tubular heat exchangers state why :

(a) the choice of tube material is only partially dependant upon its anti corrosive properties.

(b) the integrity of end cover division plates or diaphragms is of considerable consequence,

(c) heat transfer rates are only partially dependent upon circulating pump performance,

(d) parallel flow and single pass arrangements are effectively inferior to their contra flow and multi pass counterparts.

4) Describe how the following items are sometimes used to improve performance and condition of multi tubular heat exchangers:

(a) ferrous sulphate

(b) ultra violet lamps.

5) With reference to multi tubular salt water coolers:

(a) sketch a two pass cooler showing the direction of fluid flow

(b) give two faults to which it is prone,

(c) stte how these faults are countered.

6) With reference to multi tubular oil coolers define :

(a) Indications of tube leakage,

(b) reasons for tube failure,

(C) steps to locate a leak

(d) temporary corrective steps to stop leakage,

(e) permanent corrective steps to stop leakage.

7) Explain how the following conditions contribute to the satisfactory performance of multi tubular heat exchangers:

(a) tubes of approximately 15mm internal diameter and 17.5 mm external diameter.

(b) dense population in the tube nest.

(c) tube cleanliness,

(d) avoidance of low coolant flow rate through tubes,

(e) unimpeded passage of coolant at entry and exit from tubes,

8) (a) draw a line diagram of a vacuum type evaporation/distillation plant, labeling the principal items and showing the direction of flow in all lines.

(b) describe how it operates.

(c) state why the water may not be fit for human consumption.

(d) state how the water can be made fit to drink.

9) With reference to multi plate heat exchangers state why:

(a) fluid pressure and temperature does not normally exceed 10 bar and 1500 respectively,

(b) plates carry a relief pattern,

(c) plates are stainless steel and titanium whereas the tubes in multi tubular counterparts are non-ferrous,

(d) carrying bars are usually far loner than appears necessary,

(e) mass flow rate is not of major consequence.

10) Give reasons why the following actions might help correct the fault if an electric salinometer registers an unacceptable high value for the distillate from a vacuum evaporator:

(a) lower water level in evaporator.

(b) increase flow rate through brine pump,

(c) shut in coil inlet valve,

(d) shut in vapour valve

(e) give reasons why salinity should be maintained at a consistently low value.

11) State briefly what are the indications of, and the reasons for, the following malfunctions in single effect sea water evaporators:

(a) tendency to develop over pressure,

(b) tendency to prime,

(c) gradual reduction in continuous blowdown,

(d) gradual increase in distillate salinity.

12) Sketch a multi-plate heat exchanger showing how the plates are sealed.

(b) explain why working temperature and pressure can create problems in sealing, but differential expansion does not.

(c) state why carrying bars and clamping bolts appear unnecessary long.

14) (a) how would a leak in a lubricating oil heat exchanger of the tubular type be detected, it is cooled be sea water.

(b) explain how you would go about finding out the cause of the leak.

(c) if the leak was at the tubeplate expansion explain how you would rectify this fault.

(d) if the leak was due to the localized but deep pitting of a tube what other factors would you need to check.

14) (a) Draw a line diagram of a vacuum type evaporation/distillation plant using sea water feed, labelling the principal items and showing the direction of flow in all lines.

(b) If the salinometer is in-operable how can the purity of the water be assessed.

(c) Explain how by using the readings of sea water input and distilled water produced the brine density can be ascertained.

15) With respect to tubular heat exchangers :

(a) Describe two methods of allowing for differential expansion between tube and shell.

(b) The length of tube adjacent to the tube inlet is susceptible to failure for a number of reasons, discuss these.

(c) Describe a method of detecting tube leakage.

16) (a) If there has been a tube failure in an oil cooler how might this failure show itself.

(b) Explain, if the failure is in the tubeplate expansion, how the problem could be rectified.

(c) If the failure is due to pinholes in the tube itself how can the problem be rectified.

(d) Comment on the likely causes of (b)

Systems, Pumps, Etc.

18) (a) Draw a line diagram of a bilge pumping system for a dry cargo ship, labelling the principal items.

(b) Indicate the type and position of each valve fitted

(c) Explain how this system is protected against collision damage.

(d) Give reasons why the practice of endeavoring to draw the last vestige of water from the bilges with a centrifugal pump should be discouraged.

19) (a) Draw a line diagram of a central cooling system, labelling the principal items and showing the direction of flow in all lines.

(b) Describe how it operates.

(c) Define its advantages over the alternative installation of separate systems.

20) (a) Draw a line diagram of a fuel transfer and preparation system form bunker tank to boiler burner or engine fuel pump, labelling the principal items and showing the direction of flow in all lines.

(b) State why fuel is not usually transferred direct to service tanks from bunker tanks without first being held for a while in settling tanks.

(c) Define the safety measures incorporated if the system is to operate in a periodically unmanned condition.

21) With reference to self priming centrifugal pumps :

(a) Sketch a liquid ring priming pump,

(b) Explain how the priming pump in (i) operates,

(c) Explain why priming pumps are not fitted to all centrifugal pumps.

22) Identify the principal characteristics of the following pumps:

(a) Fixed stroke reciprocating,

(b) Variable stroke reciprocating,

(c) Single stage centrifugal,

(d) Gear

Select with reasons which of the listed pumps is likely to be most suitable for fuel transfer and supply duties.

23) In comparing centrifugal pumps employed for sea water circulation with those employed on other duties, explain why :

(a) Sealing ring clearances are coarser and less critical,

(b) internal inspections and overhaul is generally necessary at less frequent intervals,

(c) ancillary air pumps are of little value.

24) (a) Sketch a centrifugal bilge pump.

(b) Explain the particular need for priming such a pump,

(d) Give one advantage and one disadvantage of the centrifugal pump compared to the direct acting pump for bilge pumping duties.

25) (a) Sketch a direct acting, steam driven, reciprocating pump.

(b) Give a reason why it still finds acceptance for certain duties.

(c) Define these duties.

26) (a) Sketch a pump other than one of the reciprocating or centrifugal type.

(b) Explain how it operates.

(c) State with reasons the duty for which it is most suited.

27) (a) Sketch in cross section, a pump other than of the reciprocating, centrifugal, or gear type.

(b) Explain how it operates.

(c) Suggest with reasons a shipboard application for which it is well suited.

28) (a) Draw a line diagram of hydrosphere system (fresh water system incorporating an air reservoir) labelling the principal components and showing the direction of flow in all lines.

(b) Describe how a drop in pressure actuates the fresh water pump.

(C) state what advantages this system has over gravity head systems.

29) (a) Sketch a pump for handling hazardous chemical cargoes

(b) Describe how it operates.

(d) State how it differs from pumps handling crude petroleum cargoes.

30) (a) Draw a line diagram of a central priming system, labelling the principal components and showing the direction of flow in all lines.

(b) Describe how each pump is primed upon starting or loss of suction.

(d) State what advantages the system has over individual priming facilities.

31) Define how each of the following conditions can result in the 'fall off' in performance of centrifugal sea water circulating pumps:

(a) voyages in shallow coastal and estuarial waters,

(b) Voyages in ballast condition

(c) restricting flow by partial closure of suction valve,

(e) allowing pump to remain standing for long period with ship side suction valve open,

(f) allowing 'wear down' of pump bearings to become excessive.

32) By comparing the characteristics of the following pumps, deduce with reasons which one is best suited for the associated duty:

(a) heat exchanger sea water circulation -

Single stage centrifugal, multi stage centrifugal, direct acting reciprocating, crank driven reciprocating, positive displacement rotary,

(b) hydraulic power -

multi stage centrifugal, gear, screw, fixed stroke reciprocating, variable stroke reciprocating,

(c) noxious chemical cargo discharge -

Single stage centrifugal, multistage centrifugal, direct acting reciprocating, crank driven reciprocating, positive displacement rotary, gear, screw.

33) (a) Draw a line diagram of a fuel storage and transfer system labelling all the principal components.

(b) Indicate the type and position of each valve fitted, showing which valves can be operated from outside the machinery spaces.

(c) State how the system is protected against overpressure and overboard discharge.

34) (a) Sketch an independently driven man lubricating oil pump.

(b) Explain how it operates.

(d) Identify with reasons the clearances critical to pump efficiency.


Rudder

36) (a) Sketch a constant speed unidirectional, fixed stroke, radial type, rotary positive displacement pump for hydraulic power applications.

(b) Explain how it meets an infinitely variable demand in both directions.

(c) Given one important advantage it possesses over its variable stroke counterpart.

37) With reference to main fuel systems define the purpose of the following precautionary arrangements :

(a) duplication of settling tanks, pumps and heaters,

(b) safety devices on fuel lines,

(c) visual in supection capability of heater drains.

38) Suggest, with reasons, the most likely cause of the trouble if the performance of a centrifugal bilge pump has deteriorated to the extent that it will hardly empty the bilges under the following simultaneously prevailing conditions :

(a) pump running at normal speed,

(b) ammeter indicating slightly low current,

(c) all bilge valves, except one in use, tight shut,

(d) little evidence of air in system.

39) 39) with reference to main fuel systems define the purpose of the following precautionary arrangements:

(a) duplication of settling tanks, pumps and heaters,

(b) safety devices on fuel lines,

(c) Visual inspection capability of heater drains.

40) Suggest, with reasons, the most likely cause of ht trouble if the performance of a centrifugal blilge pump has deteriorated to the esxtent tht it will hardly empty the bilges under the folowing simultaneously preveiling conditions :

(a) pump running at normal speed,

(b) ammeter indicating slightly low current,

(c) all bilge valves, except one in use, tight shut,

(d) all strum boxes and strainers clear,

(e) little evidence of air in system.

41) (a) The vertical shaft of a centrifugal sea water pump has become worn in way of the packed gland to such an extent that sealing is becoming difficult.

(i) explain the factors which may have contributed to the excessive wear.

(ii)state one possible method of refurbishing the shaft

(b) Sketch a flexible packing unit suitable for a sea water pump and explain how it works.

42) (a) Describe clearly with the aid of a sketch, how a centrifugal bilge pump creates its own vacuum.

(b) What effect, if any, would you except from a centrifugal pump which due to its electric leads being incorrectly connected, was rotating the wrong way.

43) With reference to an electrically driven centrifugal sea water pump:-

(a) Give four reasons why the output may have fallen off.

(b) If the pump vibrates what could be the causes.

(c) Describe t test to prove the pump capacity.

44) (a) If a blilge pump has to be primed from the sea before being able to pump the bilge what is this a sign of.

(b) What forces the bilge water up the suction pipe into the pump casing.

(c) Make a sketch of an air pump suitable for a bilge pump and describe how it works.

45) (a) What is the inherent disadvantage of a packed gland for a pump.

(b) Sketch and describe a mechanical seal for a water pump showing the means used to cool and lubricate the seal and state the material of each component.

(c) Comment on the likely causes for malfunction of a mechanical seal.

46) (a) Describe with the aid of a diagrammatic sketch a fresh water system for a ship.

(b) If the water pressure was too low at the highest deck level describe in detail how you would go about rectifying this problem.

47) (a) Draw a line diagram of a fuel oil storage and transfer system indication valves and their type).

(b) Describe how the system is protected against overpressure and overboard discharge.

(c) How would you judge the rate at which you can take bunkers in a particular ship.

48) (a) Sketch a domestic fresh water system suitable for a reasonable sized ocean going cargo ship.

(b) One of the standard treatments for sterilizing dogmatic water on ships is to add chlorine, but if too much is added the water becomes unpleasant. Describe a suitable chlorine treatment unit with special reference to how the correct chlorine dosage is set and how it is maintained.

(c) State the quantity of chlorine the water should contain after the treatment, give your answer in p.p.m.

49) (a) Describe a suitable procedure for commissioning a hydraulic system.

(b) If initially a hydraulic system has been commissioned in an unclean state how is this likely to affect is operation.

(c) Identify the possible sources of contamination (assume the hydraulic oil supplied was clean)

Rudders, Steering Gears

51) with reference to hydraulic steering gears explain why :

(a) relief values are provided as well as shock valves,

(b) the pump is of constant speed, variable stroke,

(c) the ram glands are filled with soft or simple moulded packing.

52) With reference to hydraulic steering gears explain why:

(a) telemeter receivers are spring loaded,

(b) spring links are incorporated in the hunting gears,

(c)rudder movement is confined within port and starboard stops.

53) (a) Sketch a rotary vane steering gear.

(b) the pump is of constant speed, variable stroke,

(c) show how it is protected against shock,

(d) give a reason why more than four chambers are rarely provided.

54) (a) Sketch a constant speed unidirectional, variable stroke, axial type, rotary positive displacement pump for hydraulic power applications.

(b) state how it meets an infinitely variable demand in both directions.

(c) give one important advantage possessed over its radial stroke counterpart.

55) With reference to steering gears explain :

(a) how a limited amount of rudder 'drop' is accommodated,

(b) why alternative means of operating the gear is obligatory,

(c) Why maximum angular movement of the rudder is generally limited to a comparatively moderate angle port and starboard.

56) (a) Draw a line diagram of hydraulic power system for application other than steering gear in either a chemical tanker, a 'roro' vehicular ferry, or a bulk carrier, labelling the principal items.

(b) Identify with reasons those parts of the system which are likely to give rise to trouble.

(c) Define the routing maintenance required to avoid trouble-free operation of the system over an extended period of time.

57) with reference to hunting mechanisms associated with large steering gears:

(a) sketch any selected arrangement,

(b) give reasons for its incorporation in steering gears,

(c) state what periodic attention is required,

(d) define thepurpose of the spring link.

58) with reference to ram steering gears explain how:

(a) shock loading is absorbed,

(b) rudder position corresponds to the helm position at all times,

(c) rudder 'drop' is accommodated,

(d) steering gear can be operated upon failure of the bridge telemeter system.

59) Explain why the following leakage in hydraulic steering gears demands immediate attention :

(a) pipe connections in telemeter system.

(b) pipe connections in power system

(c) shock/by-pass valves,

(e) power pump glands.

60) Give reasons for the following faults in ram steering gears:

(a) in spite of purging the telemeter system before the voyage, the gear has developed an increasing tendency to wander,

(b) noticeable sluggishness after a period of heavy weather,

(c) excessive and persistent hunting.

61) (a) sketch a hunting gear as fitted to a hydraulic steering gear labelling the principal items.

(b) explain the purpose of the hunting gear.

(c) state how worn pins in the hunting gear effect steering gear operation.

62) With reference to ram steering gears explain :

(a) the purpose of the Rapsom slide.

(b) why the minimum number of rams is two,

(c) how a four ram gear can be operated on two rams only,

(e) what precautions are to be observed under conditions in (iii)

63) (a) Draw a line diagram of a hydraulic telemeter system for a ram steering gear, labelling the principal items and showing in detail both the transmitter and receiver.

(b) explain why the receiver, is spring loaded.

(c) State why the system must be maintained completely free of air.

(d) give two reasons why the oil level in the replenishment tank should be checked at regular, fairly frequent, intervals,

64) with reference to electro hydraulics steering gears explain how the ship can be steered in each of the following circumstances :

(a) destruction by fire of primary supply cables,

(b) destruction by fire of telemeter lines,

(c) bearing failure in running pump

65) (a) Draw a line diagram of the hydraulic system for a ram steering gear, labelling the principal items.

(b) Describe how the cushioning and relief arrangements function.

(c) bearing failure in running pump.

66) (a) draw a line diagram of the hydraulic system for a ram steering gear, labelling the principal items.

(b) Describe how the cushioning and relief arrangements function.

(c) state with reasons how piston and cylinder wear in the pump effects the action of the gear.

67) With reference to rotary wane steering gear state:

(a) how the fixed vanes are attached to the cylinder,

(b) how the moving vanes are attached to the rotor,

(c) how strength is imparted to the moving vanes to enable them to act as rudder stops,

(e) how rudder uplift is accommodated.

68) (a) make a simplified sketch of a rotary vane steering gear labelling the principal components and identifying he manifolds for port and starboard movement.

(b) describe how it operates,

(c) explain how the vanes and chambers are sealed.

69) (a) Itemize the checks you would carry out on a hydraulic steering gear before leaving port.

(b) Describe how you would fill the hydraulic system with a new charge of oil (assume this operation is to be done in port).

(c) List the usual contaminants found in a steering gear oil system and describe the faults that ONE containment might cause.

70) (a) Explain the principle of a hydraulic telemotor.

(b) Explain with the aid of a sketch how the hydraulic pump on a steering gear is designed to accommodate reversal of flow.

(c) How does air sometimes get into a steering gear hydraulic system.

71) With reference to steering gears :-

(a) Discuss why connecting bolts between the upper and lower rudde stock are susceptible to slackness and damage.

(b) If the bolts mentioned above were found to be slack what action and checks would you suggest.

(c) If a pintle bearing is found to be considerably worn, apart from renewing the bearing, what other factors would you check.

72) You have been sent as second engineer on a ship which has been laid up for some months which now is to be brought back in services :

(a) Itemise the checks you would carry out on the steering gear, which is of the 4 ram 2 pump unit type.

(b) If the steering gear seemed to function considerably slower when using one particular pump unit, discuss the possible reasons for this.

Shafting & Bearings

74) (a) Sketch a coupling enabling external withdrawal of propeller shafts.

(b) Give a general description of the coupling.

(c) Give one advantage and one disadvantage of this coupling compared to the solid flange type.

75) (a) Sketch a bearing carrying large diameter main transmission shafting.

(b) Explain how the bearing is lubricated and cooled.

(c) Give two reasons why such bearings occasionally overheat.

76) (a) suggest with reasons the effect long voyages in ballast may have or main transmission shaft coupling bolts.

Give reasons for the following actions when an overheated main shaft bearing is :

(b) Closely watched but left in service, unless in danger of wiping,

(c) Adjusted, even whilst on passage.

77) (a) Sketch any type of flexible coupling for main propulsion drives.

(b) Explain its operation.

(c) Explain how such a coupling can become defective.

77) With reference to main transmission shaft bearings state how:

(a) 'wear down' is measured,

(b) adjustments are made if 'wear down' is excessive,

(c) a 'wiped' bearing is make serviceable.

78) With reference to main thrust blocks:

(a) identify the critical clearances and state why they are critical,

(b) describe with detail sketches how these clearances are adjusted,

(c) give a reason why such bearings sometimes overheat although the clearances are adequate.

79) With reference to main transmission shaft coupling bolts state :

(a) Why fitted blots are used exclusively rather than clearance blots with dowel pins,

(b) why excessively tight bolts should into be forced into the couplings,

(c) Why excessive tightening of coupling bolts should be discouraged,

(d) what is the major disadvantage of using fitted blots in these couplings.

80) (a) Sketch a sealing arrangement for an oil lubricated stern tube.

(b) Identify the common forms of seal failure.

(c) State how oil loss due to seal failure can be restricted whilst on passage.

81) With reference to main thrust blocks state why :

(a) cooling coils are sometimes fitted in the sumps,

(b) many are self lubricated, that is, independent of main Lubricating oil system.

(c) axial clearance between collar and pads is minimal,

(e) they occasionally overheat,

(f) they are generally located in close proximity to the main engine rather than the propeller.

82) (a) Describe how propeller shaft/stern bearing clearance is measured.

(b) Identify with reasons the major factors which substantially determine the range of permissible clearance.

(c) State with reasons what parts of propeller shafts should receive particularly close inspection upon withdrawal of such shafts for survey.

(d) State why some propeller shafts require less frequent inspection that others.

83) Explain how the following conditions generally result in the fretting of main transmission shaft coupling bolts.

(a) excessive force required to drive home bolts due to excessive tightness of blots in holes,

(b) slack fit of bolts in holes,

(c) nuts not tightened up sufficiently.

(d) poor alignment of shafting,

(f) shafting continuously subject to severe propeller vibration.

84) (a) Sketch a hydraulic coupling between a medium speed diesel engine and reverse/reduction gear.

(b) Describe how it operates.

(c) State what advantages such couplings have over their friction, powder and magnetic counterparts.

85) (a) Describe the 'Pilgrim Wire' method of checking alignment of main shafting.

(b) Explain how the readings are recorded and interpreted.

(c) afloat without cargo,

(e) afloat with full cargo,

(f) in dry dock.

86) Give reasons why the following conditions can cause vibration in main transmission shafting :

(a) ship in ballast,

(b) poor cargo distribution,

(c) damaged propeller blades,

(d) propeller operating in critical speed range,

(f) main engines working on overload.

87) Define, in each case, the conditions under which each of the following courses of action might be considered appropriate, upon the running temperature of a main transmission shaft bearing reaching and remaining at an unacceptably high level:

(a) check condition of adjacent bearings,

(b) flush bearing through with oil or a mixture of oil and soft soap,

(c) reduce shaft revolutions and hose bearing,

(d) stop ship and adjust bearing.

88) while inspecting the tailshaft after withdrawal from stern tube a crack is found in the non-ferrous liner:

(a) How important is this crack and why ?

(b) How would you determine the true extent of the crack.

Tailshafts are susceptible to cracks, give reasons for this.

89) (a) Describe with the aid of a sketch the construction of a single collar thrust bearing.

(b) Explain the principle on which it works.

(c) Explain how you would take the essential clearances and explain the significance of them.

90) (a) Why is the axial clearance of a main thrust bearing an important dimension.

(b) How is this clearance measured.

(c) Describe how the thrust pads are removed for inspection and state what you would look for in particular.

91) (a) What are the advantages of a propeller shaft with its after end flanged compared with a shaft with flange in-board.

(b) With reference to a stern bering, describe how seals are prevented from causing grooves in the shaft.

(c) Describe with the aid of a sketch, how a stern tube is held into the stern frame, and give details of how the tube can be designed so that some alignment adjustment is possible.

92) (a) What are the likely results of running machinery not properly lined up.

(b) Explain THREE methods of lining up an electric motor with a horizontal spindle centrifugal pump.

(c) What factors prevent absolute accuracy in (b)

93) With reference to main thrust blocks explain why:

(a) although the shaft collar runs against the ahead pads for most of the ship's life, yet the total axial clearance between the collar and both sets of pads seems unnecessarily small,

(b) although the trust block housing is of heavy construction, yet unacceptable axial movement of the main transmission shafting is sometimes experienced.

(c) location is as near the main propulsion machinery as possible,

(d) pads are not normally arranged in a full circle around the collar,

(f) journal bearings are incorporated fore and aft of the collar.

94) (a) Sketch a stern seal arrangement installed in association with an oil lubricated stern tube or stern bearing, identifying the various components of the seal.

(b) State how ingress of sea water into the stern tube is prevented.

(c) Describe the corrective action possible whilst the vessel is afloat, should the seal fail to remain tight.

State why two stern seal oil header tanks are fitted in some instances.

95) (a) Give THREE possible reasons for excessive loss of lubricating oil from the stern gland seal system.

(b) Outline the appropriate courses of action that should be taken in order to eliminate or reduce the effect of this loss.

96) (a) What is the purpose of the main thrust bearing.

(b) When checking the main thrust bering, what dimensional checks would be necessary.

(c) How is a thrust bearing cooled.

(d) Describe, with a sketch, the special chocking arrangements normal to thrust bearing.

97) (a) Main transmission shaft bearings occasionally overheat, give reasons why this happens.

(b) What can the ships engineer do to overcome this over-heating problem.

(c) Describe a monitoring system for a shaft bearing.

CONTROL

99) With reference to auxiliary engines describe transducers suitable for producing either electrical of pneumatic signals to indicate :

(a) Lubricating oil pressure,

(b) jacket cooling water temperature.

100) (a) Sketch a diaphragm operated control valve of any design.

(b) State how load changes are sensed.

(c) State how command signals re transmitted to actuators.

101) (a) Describe two different methods for the remote measurement of fluid flow through a pipe.

(b) Compare the accuracy of the methods.

(c) Give one cause of error in each method.

102) (a) Sketch two arrangements for determining remotely the quantity of liquid in tanks.

(b) Compare the accuracy of these methods.

(c) Describe how the signals are converted and fed into an automatic recording and control

103) (a) Explain how the condition of air used in pneumatic control systems is kept within closely defined limits.

(b) State what routine maintenance and tests are needed to keep the system fully operational.

(c) State why independent compressors are preferable to bleeding from main or auxiliary starting air reservoirs.

104) (a) Sketch a pneumatically controlled valve for maintaining a constant pressure in steam or air ranges.

(b) Explain how it operates.

(c) state how the valve differs for steam or air services.

105) (a) Sketch a differential pressure alarm fitted across an oil filter.

(b) Explain how it operates.

(c) State how it can be tested whilst the filter is on service.

106) Describe transducers for producing electrical or pneumatic signal to indicate:

(a) Lubricating oil pressure of auxiliary diesel engines,

(b) Exhaust temperatures of same engines.

(c) State how each of these transducers can be tested.

(d) Explain how an alarm is energized if either the pressure or an exhaust temperature goes outside the set limits.

107) (a) Sketch a pneumatically operated valve for regulating coolant flow.

(b) Explain how instantaneous valve position is regulated.

(c) State how valve position is indicated at the console.

108) (a) Sketch an arrangement for indicating propeller shaft speed at a position remote from the shaft.

(b) Explain how it operates.

(c) State how, with this system, inaccuracies occur and are kept to a minimum.

109) Describe with sketches circuit transducers for producing electrical or pneumatic signals to indicate :

(a) main lubricating oil pressure,

(b) cylinder jacket cooling water temperature,

(c) state how each transducer is tested.

110) With reference to pneumatic control systems explain why:

(a) filters re fitted to compressor suctions,

(b) filters and separators are fitted between compressors and air receivers,

(c) filters and dryers are fitted between receivers and air mains.

114) With reference to direct expansion refrigeration plans used in conjunction with ships' stores lockers:

(a) sketch an automatic expansion valve with thermostatic control,

(b) describe how it operates,

(c) explain with sketches how the temperature sensitive element located in the lockers controls the circulation of refrigerant.

115) (a) state why a pneumatic control system requires clean dry air.

explain how the following pollutants are dealt with :

(b) water

(c) oil

(d) dust and dirt.

116) (a) Draw a line diagram of an arrangement whereby the pressure of oil delivered to a main lubricating oil system by a constant speed, positive displacement, pump is pneumatically controlled within set limits.

(b) Trace the sequence of events resulting from deviation in oil pressure.

(c) State why a control valve is used to preference to altering pump speed.

117) (a) Draw a line diagram of a control system to operate widely distributed valves from one station, labelling the principal components

. (b) Describe how any one valve is remotely manipulated.

(C) Explain how the condition of all valves can be ascertained at any time.

(d) Suggest with reasons a shipboard application of such a system.

118) Describe with sketches a device giving audible and visual alarm under either of the following conditions.

(a) burst fuel pipe,

(b) overheated bearing in main machinery.

119) (a) Sketch a pneumatic controller employing the nozzle/flapper principal.

(b) Explain why a restrictor is fitted in the air supply line.

(c) State why the diameter of this restrictor is smaller than that of the nozzle orifice.

(d) Describe how the controller is checked for accuracy.

120) (a) Sketch a diaphragm operated control valve of any design.

(b) State how flow changes are sensed.

(c) State how command signals are transmitted to actuators.

121) (a) Describe with sketches a bridge/engine room telegraph interconnecting gear.

(b) Explain the how the system may operate a "wrong way" alarm.

122) Describe with sketches instruments used for measuring the ambient temperature in the following spaces :

(a) refrigerated compartment.

(b) main machinery exhaust gas uptakes.

123) with reference to a control system :

(a) what are the signs of an unstable system.

(b) Choose a system with which you are familiar and itemise the checks you would make to determine "the cause of instability.

124) With reference to a large air operated control valve of the diaphragm type

(a) Explain how the length of stroke can be altered.

(b) Explain how the speed of opening (or closing) is changed.

(c) Describe how the position of the valve i.e. 'open' or 'closed' can be led to a monitoring station.

125) (a) Bridge control of main engine speed is now common, describe such a system with the aid of sketches if necessary.

(b) How is this system checked before leaving port.

(c) How can the engine room staff over-ride bridge signals if necessary.

126) (a) Sketch a pneumatically operated diaphragm control valve with a double valve/double seat arrangement, and itemise the main parts.

(b) Explain why a moulded diaphragm is advantageous as far as control is concerned.

(c) What are the advantages of a double valve compared with the single valve design.

127) Explain the automatic controls of a sea water evaporator so that is can be part of the UMS mode. Your answer which should be complete with diagrammatic sketch should cover output, brine density, brine level and the purity of made water.

(a) Sketch a closed loop control system, identify the three basic parts, and describe how the system works.

(b) Describe how the closed loop system is used in the control of an a.c. generator.

128) (a) Make a diagrammatic sketch of a salinometer which would be suitable for a sea water evaporator.

(b) Describe how this instrument works.

(c) List three common faults with regard to accuracy of reading.

129) The measurement of oxygen in an exhaust gas can be most helpful in assessing combustion efficiency but its measurement for an enclosed space about to be entered is critical for human safety.

(a) Describe the principles of an oxygen meter.

(b) How is the meter's calibration checked.

(c) How can false readings occur.

130) (a) Describe with the aid of a sketch a suitable means of remotely gauging the depth of liquid in a tank.

(b) What factors can influence the accuracy of the reading.

131) (a) Sketch in block form a 'closed loop' and also an 'open loop' control system.

(b) Describe the controls you would expect to find on a fuel oil separator plant designed to operate fully automatically.

132) With reference to a control system :

(a) Comment on why it may become unstable.

(b) Choose a system with which you are familiar and itemise the checks you would make to determine the cause of

133) Describe with the aid of sketches the principle of operation of the following instruments:

(a) tachometer

(b) pyrometer

(c) floweret

134) Itemise the principal causes of irregular operation of a pneumatic diaphragm operated reducing valve and how they are remedied.

135) With reference to a pneumatic control system sketch and describe the following :

(a) drier

(b) filter

(c) automatic compressor drain

(d) automatic stop/start.

136) With reference to automatic control explain the meaning of five of the following terms :

(a) Closed Loop

(b) Reference input signal

(c) Dead band

(d) Deviation

(e) Gate

(f) Address

137) Remote control of main machinery is now very common and with this in mind explain :

(a) how the number of automatic and consecutive attempts which fail to start are limited.

(b) the system of interlocks which prevent simultaneous control from bridge and engine room.

(c) the starting air system is provided with an alarm, what is the significance of the pressure at which the alarm is set.

Materials

139) (a) State why the properties of mild steel make it suitable for many marine engineering purpose.

(b) State why the tensile strength of steel cannot be increased without decreasing the malleability, ductility and weldability.

(c) Give two instances in marine engineering where the physical properties of steel are modified by alloying, giving reasons for this modification.

140) By comparing the physical properties and metallurgical compositions of the following metals deduce with reasons which one is best suited to the associated application :

(a) reduction gear pinion -

mild steel, nodular cast iron, monel metal, gun metal, nickel- chrome steel, muntz metal.

(b) gas or steam tubine blade for service temperature in excess of 5000C -

mile steel, phosphor bronze, monel metal, stainless steel, nickel-chrome steel, brass,

(c) tube of sea water cooled oil cooler -

mild steel, phosphor bronze, muntz metal, stainless steel, titanium, aluminium bronze, copper.

141) By comparing the physical properties and metallurgical compositions of the following metals, deduce with reasons which one is best suited for the associated duty:

(a) auxiliary diesel engine pistons- cast iron, cast steel, aluminium,

(b) condenser tubes - brass, aluminium bronze, stainless steel.

142) Outline THREE main requirements of a material used in the construction of a pressure vessel.

(a) State ONE material used in the construction of the vessel.

(b) Explain how a welded joint could cause failure of the vessel.

143) Suggest a typical shipboard machinery application for each of the following metals and explain how their properties make them particularly suitable for the stated application :

(a) stainless steel,

(b) grey cast iron

(c) aluminium bronze,

(d) monel metal,

(f) cupro nickel.

144) By comparing the physical properties and metallurgical composition of the following metals, deduce with reasons which one seems best suited for the associated duty :

(a) safety valve or relief vale spring -

minckel-chrome steel, chrome-molydenum steel, stainless iron, monel metal, forged steel, cast steel, silicon-manganese steel,

(b) refrigerant condenser tubes -

monel metal, stainless steel, copper, aluminium brass, phosphor - bronze, cupro nickel, mild steel,

(c) main shaft plain bearing -

phosphor bronze, babbitt metal, copper, lead, mild steel, brass, cast iron.

145) (a) Describe a method of tracing a crack that is only partially discernible to the naked eye.

(b) Explain how propagation of such a crack can be arrested.

(c) Describe a cold process of repairing cracked machinery components 'in situ'.

(d) Give a disadvantage of the method described.

146) (a) outline two main properties of materiel used for the construction of diesel engine crankshafts.

(b) State two crank shaft materials.

(c) Outline two reasons why one of these materials might be used in preference to the other.

147) With reference to welding :

(a) Comment on the basic difference between not and cold cracking and explain how ductility is an important factor.

(b) Draw a simple sketch showing 'undercut' and give two reasons why it occurs.

(c) What effect may result from using damp electrodes and now can this be avoided.

LUB OILS

149) The specifications for two liquid fuels are as follows:

(a) (b) Specific gravity 0.942 0.981

Viscosity (c St) 120 365

Pour point (0C) 9.8 35.2

Vanadium (ppm) 120 90

Sulphur (%) 3.2 4.9

Carbon residue (%) 8.2 10.4

(a) Suggest with reasons the application for which (a) is likely to be most suitable.

(b) Suggest with reasons the application for which (b) is likely to be most suitable.

(c) Define the significance of the sulphur % as given for each fuel application.

150) Describe how it is determined whether lubricating oil deterioration is due to contamination by :

(a) fuel oil,

(b) fresh water,

(c) sea water,

(d) combustion products.

(e) state why lubricating oil constitutes a particularly dangerous fire hazard.

151) With reference to fuel for either motor or steam propulsion :

(a) specify the chemical constituents of the fuel selected,

(b) identify the impurities in the fuel and the compounds formed upon combustion,

(c) describe the effects of the compounds in (ii) on plant operation and maintenance.

152) (a) Specify with reasons where test samples should be drawn from a main lubricating oil system.

Describe shipboard tests to determine:

(b) water content,

(c) acidity,

(D) suspended solids.

(e) flash point

153) (a) State how and why lubricating oil deteriorates in main lubrication systems.

(b) State how deterioration becomes apparent.

(c) Describe simple shipboard tests to determine the degree of contamination.

Give a reason in each case, why each of the following conditions of lubricating oil is unacceptable :

(d) high acidity,

(e) significant fuel contamination,

(g) significant fresh water contamination.

154) (a) Draw a line diagram of a lubricating oil storage, settling, replenishment and purification system as far as the main lubricating oil pump, labelling the principal items and showing the direction of flow in all lines.

(b) Explain why setting and purification facilities are provided.

(c) State why reserve capacity is provided.

155) (a) Give reasons why cleanliness is so important for hydraulic systems.

(b) Explain how a system, which was originally quite satisfactory, can become contaminated, even though any make up added has been pure.

(c) What are the usual signs of contamination.

Fuel Oils

157) (a) State why it is necessary to control the temperature of heavy distillate fuel within close limits before burning.

(b) Define the effects of allowing the oil temperature to vary outside these limits.

Describe the tests to evaluate the following properties of liquid fuel:

(c) viscosity,

(d) closed flash point.

Account for any inaccuracies in the tests.

158) (a) Identify the factors which may limit the speed at which bunkers may be taken on board.

(b) Describe a system with specific reference to preventing over flows.

(c) Describe an automatic alarm suitable for fitting into a bunker tank to signal that the tank is practically full.

Feedwater, Etc

160) (a) Suggest with reasons which four of the following impurities in the feed water of a 'package' boiler operating at 7 bar, dry saturated, are likely to contribute most to scale formation :

silica,

iron compounds,

sodium chloride,

magnesium bicarbonate,

calcium bicarbonate

calcium sulphate

soidum sulphate

magnesium chloride.

(b) Define briefly the water treatment required to ensure the precipitation of scale in a soft form.

161) with reference to water made by a distillation plant, which is to be used for drinking purpose.

(a) what further treatment is necessary to ensure biological purity.

(b) How is the treatment mentioned in (a) controlled.

(c) Distilled water is usually 'flat' to the taste, how can this be improved.

(d) How is the purity of water taken on board from a shore supply checked for purity.


Fires and explosions

163) (a) Draw a line diagram of a multi bottle carbon dioxide fire smothering installation excluding the spaces covered.

(b) Describe how gang release functions.

(c) State what action is necessary if the gang release fails to operate.

164) (a) Give two possible causes of electrical fires at switchboards and in electrical machines and wiring.

(b) Describe how a large electrical fire can be quickly controlled.

(c) State how the risk of electrical fires can be reduced.

165) State what precautions need to be observed in order to avoid or contain an outbreak of fire arising from the presence and use of the following equipment aboard a vessel afloat at a repair berth :

(a) electric are welding equipment,

(b) acetylene and oxygen bottles and hoses,

(c) temporary lighting and wandering power cables,

(d) flammable liquids, paints and varnishes,

(e) cotton waste and rags.

166) With reference to a ship's firemain explain how :

(a) provision is made for an alternative supply of water in the event of failure of the engine room fire pump,

(b) integrity of the main is maintained in the event of destruction of the main within the machinery spaces,

(c) damage to the main can be avoided in sub zero atmospheric conditions.

167) With reference to fire smothering system ;

(a) differentiate between the nature and manner of extinction of chemical and mechanical foam,

(b) describe with line sketches a mechanical foam system covering the machinery spaces,

(c) specify the routine testes applied to ensure full operational capability of system (ii) at all times.

168) (a) Suggest with reasons the principal causes of fire in accommodation and service spaces both at sea and in port.

(b) Sketch a fire detector commonly used in conjunction with a alarm belt circuit.

(c) State how compensation is made for a slow change in ambient temperature.

(d) explain why fire my spread more rapidly in a ship under repair in a yard than when at sea.

169) (a) Sketch in detail a portable carbon dioxide fire extinguisher.

(b) State why the tare weight is marked on the body.

(c) Suggest with reasons, for which fires it is most suitable.

(d) Suggest why in certain circumstances it can be fore of a hazard than a help in untutored hands.

170) With reference to fixed carbon dioxide fire smothering systems explain :

(a) how rupture of the bursting disc on a gas cylinder does not result in loss of gas,

(b) Why the nozzles are generally distributed well down in the machinery spaces but not in cargo spaces.

171) Give reasons why fires occasionally occur in each of the following localities :

(a) boiler flats high up in the machinery space,

(b) purifier flats,

(c) engine exhaust trunking,

(d) define the means employed in each case for extinction and prevention of reignition.

172) (a) Draw a line diagram of s sprinkler system, labelling the principal components and showing the direction of flow in all lines.

(b) Describe how it operates in the event of a minor fire in a small compartment.

(c) State how operation differs in the event of a major fire in a large compartment.

173) (a) Draw a line diagram of a firemain serving both deck and accommodation spaces, labelling the principal items.

State how an uninterrupted supply of water is still maintained under each of the following conditions :

(a) failure of the engine room fire pump,

(b) destruction of the engine room firemain,

(c) vessel assuming a servere list.

174) State with reasons what types of fire each of the following portable extinguishers is likely to be most effective in extinguishing.

(a) soda-acid

(b) dry powder

(c) carbon dioxide

(d) foam

(e) State why(d) needs occasional recharging although it has not been used.

175) state how and why the following equipment is shut down during a major fire which has necessitated the evacuation of the machinery spaces :

(a) settling and service tank valves,

(b) fuel transfer and supply pumps,

(c) mechanical and natural ventilation

(d) State how the fire is brought under control using the facilities available outside the machinery spaces.

176) Describe how outbreaks of fire in the following instances can be extinguished : (a) bales of cotton waste or similar material in store rooms,

(b) bagged flammable powders in cargo bolds,

(c) oil fuel spills on boiler flats,

(d) suggest with reasons why (c) is potentially the most dangerous situation.

177) (a) Describe with sketches any one of the following portable fire extinguishers:

Chemical foam,

Carbon dioxide,

Dry powder,

(b) Suggest why n certain instances carbon dioxide and dry powder can be more of a hazard than a help in untutored hands.

(c) Suggest why dry powder is possibly more effective than carbon dioxide for switchboard fires,

(d) State why chemical foam extinguishers occasionally require recharging even though they have not been used.

178) Identify with reasons which of the following courses of action would be advisable and which ones would not be advisable if a firm has filled the accommodation with thick acrid smoke :

(a) use all means available to disperse smoke (main ventilation, portable exhauster fans and ducting) before entering with water hose,

(b) seal accommodation off from the atmosphere and inject carbon dioxide through a vent opening,

(c) dispatch a person wearing a smoke helmet into the accommodation with a hose or portable extinguisher,

(d) dispatch two persons wearing self contained breathing apparatus into the accommodation to reconnoitre and report back,

(e) allow all smoke emitting combustibles to burn away before going in to tackle the fire.

179) (a) Draw a line diagram of a complete inert gas system incorporating an autonomous gas generator, labelling the principal items and showing the direction of fluid flow in all lines.

(b) describe briefly how optimum quality of gas is achieved,

180) (a) Draw a line diagram of a carbon dioxide, bulk storage, fixed fire smothering installation, labelling the principal items and showing the direction of flow in all lines.

(b) list the safety devices built into the installation.

181) (a) Draw a line diagram of a fire smothering and tank inerting system using gas from the main uptakes, labelling the principal components and showing the direction of flow in all lines and ducts.

(b) Describe the scrubbing process and state its purpose.

(c) State what safety devices are incorporated in the system.

182) Suggest with reasons which one of the following extinguishers seems Best suited for engaging the associated fire :

(a) local but intense oil fire on tank tops -

water hose (jet or spray), portable carbon dioxide, dry powder, soda acid, portable foam,

(b) accommodation fire in cabin -

portable carbon dioxide, soda acid, dry powder, water hose, carbon tetra chloride.

183) Suggest with reasons which ONE of the following extinguishers seem best suited for engaging the associated fire :

(a) large pan of fat blazing fiercely on hot galley stove-water nose (jet or spray), dry powder, portable foar, portable carbon dioxide,

(b) electrical insulation smoldering behind 'dead front' switchboard

- fine water spray, portable foam, soda acid. Dry powder,

- portable carbon dioxide.

184) (a) Describe with the aid of a single block sketch an inert gas system for a tanker.

(b) What should happen to the system if the oxygen content of the gas rises to an unacceptable degree.

(g) Explain why inert gas systems are so prone to corrosion attack.

185) On taking over as second engineer on a ship which has been laid up for some months : (a) itemise the checks you would carry out on the multi-bottle CO2 fire extinguishing system.

(b) How would you assess the state of the portable fire extinguishers in the engine room.

(g) What other items concerning fire fighting you need to check.

186) (a) Explain the conditions usually associated with spontaneous combustion, and give one example of how this type of fire might occur in an engine room.

(b) The use of paints, varnishes and glues may constitute a fire hazard , explain why this is so and describe how this risk may be reduced.

(c) State FOUR ways in which a ships engineer can significantly reduce the risk of fire in an engine room. Ignore the risks mentioned in (a) and (b)

187) (a) Describe in detail how you would completely check a CO2 fire extinguisher system which is of the multi-bottle type.

(b) State when you would prefer to do this check i.e. at sea or in port and give your reasons.

188) (a) Engine room fires usually result in enormous quantities of smoke, why is this.

(b) Why is this smoke in some ways more dangerous than the fire itself.

(c) How can this smoke from a fire be controlled.

189) Assuming that a serious fire has started on the top of a diesel generator : (a) What are the most likely causes of the fire.

(b) Itemise the important steps you should take in some order of priority.

(c) What will be, almost certainly, the immediate consequences of this type of fire.

190) (a) Sketch a 'gang release' CO2 system.

(b) Why are the larger CO2 systems designed for 'gang release'.

(c) Make a sectional sketch through the top of a CO2 bottle clearly showing how the rotation of the release handle allows the CO2 to flow to the manifold. All items should be named.

191) (a) Sketch a sprinker system suitable for protecting an engine room space on a large ocean going cargo vessel.

(b) Explain how the 'section alarm' and 'test circuit' systems work.

192) (a) Why are special precaution often taken with regard to fire risks of oil separators.

(b) Describe in detail how the risks can be reduced.


Insulation Resistance

193) (a) State the effect which temperature has on the insulation resistance of electrical machinery.

(b) Explain why the insulation resistance of an idle electrical machine is at greater risk of determoration than that of a continually running machine.

(c) Describe a procedure for carrying out systematic checks on the insulation resistance of an electrical machine.

194) (a) Explain how the insulation resistance of a material can be measured.

(b) Describe the factors affecting insulation resistance.

(c) Describe a procedure for testing and recording the insulation resistance of an electric motor.

195) With reference to a.c. portable appliances aboard ships :

(a) Explain why the risk of electric shock is greater than that associated with fixed electrical installations.

(b) Briefly explain how a 115 V supply from a transformer can be adapted to limit the shock risk to personnel to a maximum of 60 V and state why this voltage limitation is considered necessary.

(c) Briefly describe the conditions which can increase the dangers of electric shock tc personnel and state the effect those conditions have on the human body.

196) (a) State why it is necessary to dry out electrical machinery after accidental immersion in water.

(b) Describe a method of drying out the windings of an a.c rotor stating any precautions that should be taken.

(c) Describe a suitable procedure for putting back into service an electrical machine which has been subjected to a drying process.

197) (a) Briefly describe the factors contributing to the deterioration of insulation resistance on marine electrical machinery.

(b) Explain how insulation test reading are made and interpreted.

(c) Describe a suitable on board procedure for drying out an electric motor.

198) (a) Briefly describe the factors which contribute to the deterioration of insulation on marine electrical machinery and how these factors are taken into account in the design of the equipment or in its operation.

(b) Describe briefly how insulation test readings are taken and interpreted.

199) (a) Explain what effects accumulation of dirt may have on electrical insulation of machinery.

(b) State the possible consequences of allowing the ventilation ducts of machinery to become choked with dirt.

(c) State the precautions necessary when cleaning heavy deposits of dirt from the insulated winding of electric motors.

200) (a) List desirable properties of electrical cable insulation onboard ship,

(b) Explain why insulation of an idle machine may risk greater deterioration than a running machine.

201) (a) Briefly describe how the condition of electrical insulation may be measured.

(b) Explain how the amoient atmospheric conditions may influence the instrument readings.

Electrical Systems, Batteries, Etc

203) With reference to a bank of emergency lead-acid batteries :

(a) State the condition of the battery bank if the specific gravity of a number of cells in the bank is in the region of 1.11, with an ambient temperature of 160 C,

(b) describe a systematic procedure for checking the condition of the battery bank if it is divided into two sections for charging.

(c) describe the necessary routine maintenance.

204) (a) List the electrical systems aboard ship where continuity of supply from emergency sources if essential in the event of mains power failure.

(b) Briefly describe the major features of a typical emergency electrical supply system.

(c) Explain how an emergency a.c. generator can be arranged to start automatically in the event of mains power failure.

203) With reference to an emergency source of electrical power in cargo ships:

(a) Describe a typical power source.

(b) Give a typical list of essential services, which must be supplied simultaneously.

(c) Explain how the emergency installation can be periodically tested.

205) (a) State the form of protection provided for electrical equipment associated with a ship's steering gear.

(b) Explain the difference between short circuit and overcurrent protection of electrical equipment.

(c) Explain how the setting of an electrical overload protection device is determined.

206) (a) State why earth faults must be cleared an soon as possible.

(b) With the aid of a wiring diagram explain how earth faults.

(c) Briefly describe how an earth fault on a three phase insulated system is located.

207) (a) Explain why the risk of electric shock is greater with a.c. portable appliances than with fixed appliances.

Briefly describe how the risk of shock to personnel can be minimized on board ship by :

(b) design of the electrical system,

(c) care in operation of equipment.

208) (a) Briefly describe the general effect if a shore supply of 60 Hertz was connected to a ship system designed to work on 50 Hertz.

(b) State the effect on a motor designed to run on 50 Hertz supplied with a frequency of 45 Hertz.

(c) Explain why a stalled squirrel cage motor would burn out if the protective devices failed to operate quickly.

209) (a) State why incandescent lamps can be dimmed by simply regulating the applied voltage whereas this method cannot be used with gas discharge lamps.

(b) State under what circumstances the assumption that, a lamp maintains its value as long as it still functions, is wrong.

(c) State FOUR factors which influence the life of gas discharge lamps.

210) (a) Briefly describe how storage batteries may be charged from high voltage a.c supply.

(b) State two methods by which the condition of an alkaline storage battery may be checked.

211) Briefly explain the function of the following stating where it may be used on board ship :

(a) Rectifier,

(b) Thyristor,

(c) Transistor

212) (a) Explain the effect of connecting up a 60 Hz supply from ashore to a ship's normal 50 Hz system.

(b) State the checks that need to be made before a shore supply is connected up.

(c) Explain why it is necessary to earth the ship.

213) (a) Briefly describe the protection provided for electrical equipment associated with a ships steering gear.

(b) State the checks that need to be made before a shore supply is connected up.

(c) Explain why it is necessary to earth the ship.

214) (a) Briefly describe the protection provided for electrical equipment associated with a ships steering gear.

(b) Distinguish between short-circuit protection and over-current protection.

(c) Briefly describe how the setting of an electrical overload protection device can be checked.

215) With the aid of sketch explain the effect of:

(a) a single earth on a circuit.

(b) two earths on a circuit.

(c) Describe a test to ascertain earthing of a circuit on board ship where earth lamps are not in operation.

(d) State how an earth would be located once it is ascertained to exist in a particular circuit.

216) (a) Distinguish between 'Primary cell' and 'Secondary cell' and between 'acid cell' and 'alkaline cell'.

(b) Describe how a battery of alkaline cells may be tested for its usefulness after a lone storage and if found deficient how it can be remedied.

217) With reference to fuse protection for an a.c. induction motor :

(a) State the reason for this form of protection.

(b) State the factors that need to be considered when selecting the correct fuse rating.

(c) Briefly describe the procedure to follow if fuse replacement are continually blowing.

218) (a) Giving a set of typical readings, describe how the condition of a lead acid storage battery can be checked.

(b) State whether the ambient temperature is relevant while ascertaining the condition of the battery and if so how is it relevant.

(c) Briefly describe the care and routine maintenance that would be necessary with a bank of emergency lead-acid batteries.

219) (a) List the essential systems aboard ship which require the back up of an emergency battery bank.

(b) Describe how an emergency battery bank is maintained in a fully charged condition.

(c) Outline a routine maintenance procedure for a bank of lead-acid batteries

220) (a) Draw a complete circuit diagram for an emergency a.c. electrical supply system showing the connection to essential services and protection devices.

(b) Describe how the system comes into effect in case of a 'black out'.

221) (a) Briefly describe a typical emergency power source for cargo ships stating its location and method of periodic testing.

(b) Give a typical list of essential services which would normally be supplied by this emergency power source.

222) (a) Sketch a line diagram for earth detector lamps or a three phase insulated a.c. system.

(b) State how earth faults are indicated and interpreted,

(c) State why earths must be traced and rectified as soon as possible.

223) (a) Explain why earthing of the neutral wire in three phase a.c. systems requires an earthing resister,

(b) Briefly describe how the magnitude of such a resister is chosen.

(c) draw a simple line sketch shoeing such an earthing arrangements.

224) (a) State what is meant by flame proof equipment, with respect to hazardous atmospheres.

(b) Sketch and describe how the "mechanics" of flame extinction are achieved in a flame proof lamp fitting.

(c) Describe what precautions are taken when reassembling a flame proof

(i) lamp fitting

(ii) motor

after having been removed ashore for overhaul, and comment as to the inspection you would give to this equipment after having been repainted by ship's staff.

225) (a) Describe the possible effects of dirt accumulating in electrical machines.

(b) Describe suitable procedures for cleaning electrical machines, which are heavily contaminated with dirt deposits.

(c) Explain why re-varnishing of electrical machines is carried out and the necessary precautions to be observed.

226) (a) Explain the meaning of single phasing in a.c. machinery.

(b) State the dangers associated with single phasing and the protective devices normally fitted to counteract such dangers.

227) With the aid of circuit diagrams suggest with reasons which ONE or combination of the following faults in a three phase a.c. circuit will give rise to the following condition of the earth lamps:

Phase I,Slightly dull; Phase II,dark ; Phase III,half brilliance

Phase I Phase II Phase III

(a) heavy earth no earth light earth

(b) no earth dead earth light earth

(C) light earth heavy earth light/heavy earth

(d) light earth heavy earth light/heavy earth

228) (a) Given a set of typical readings, describe how the condition of a lead acid storage battery can be checked.

(b) State whether the ambient temperature is relevant while ascertaining the condition of the battery and if so how is it relevant.

(c) Briefly describe the care and routine maintenance that would be necessary with a bank of emergency lead-acid batteries.

229) (a) Distinguish between 'Primary cell' and 'Secondary cell' and between 'acid cell' and 'alkaline cell'.

(b) Give an example of a primary cell.

(c) Describe how a battery of alkaline cells may be tested for its usefulness after a long storage and if found deficient how it can be remedied.

230) (a) Explain why the risk of electric shock is grater with a.c. portable appliances than with fixed appliances.

(b) Briefly describe how the risk of shock to personnel can be minimised on board ship by :

(i) design of the electrical system, and

(ii) care in operation of equipment.

231) With reference to three phase induction motors :

(a) State the precautions necessary before maintenance work can be carried out.

(b) State the type of bearings normally fitted and give reasons for their choice.

(c) Explain why such a motor might run in the wrong direction and how the fault would be corrected.

232) (a) State the general effect of connecting a ship's electrical system based on a frequency of 50 Hertz with a shore supply of 60 Hertz.

(b) Describe the effect on an a.c. electric motor which is supplied with current at a frequency lower than that for which the motor was designed.

(c) Explain why a stalled squirrel cage motor would burn out if the protective devices failed to operate quickly.

233) With reference to three phase a.c. motors :

(a) State the limitations of direct on line starting.

(b) Describe a method of starting other than direct on line.

(c) Explain why the motor designed for delta connected windings must not be connected so that the motor runs star connected.

234) (a) Explain why dirt should not be allowed to accumulate on insulation surfaces between exposed live parts on electrical equipment.

(b) Describe the possible consequences of allowing ventilation ducts on electric motors to become choked with dirt.

(c) Describe the precautions necessary when cleaning heavy deposits of dirt from the insulated windings of electric motors.

235) If an electrical machine aboard ship becomes accidentally immersed in sea water :

(a) State why sea water can be particularly damaging to the machine and briefly describe any remedial action necessary prior to carrying out a drying process.

(b) Explain how the machine should be dried out and the precautions necessary to ensure that the drying process is satisfactory.

(c) Explain how it is determined that the drying process has been satisfactorily completed.

236) with reference to fuse protection for an a.c. squirrel cage motor :

(a) State the reason for this form of protection.

(b) State the factors to be considered when selecting the correct fuse rating.

(c) Describe the procedure to follow if fuse replacements are continually blowing.

237) (a) Describe briefly the function of slip rings in electrical machines.

(b) Mention the regular attention necessary to such components and possible dangers if maintenance is neglected.

(c) State the approximate pressures on slip ring brushes and describe briefly how slip rings may be cleaned.

238) (a) Explain why it is necessary to restrict current in starting an a.c. motor.

(b) Mention two such methods of starting and indicate the suitability of each for particular operation.

(c) State the maintenance necessary to keep starters in good working order.

239) (a) Explain the meaning of single phasing in a.c. machinery.

(b) State the dangers associated with single phasing and the protective devices normally fitted to counteract such dangers.

240) (a) State the precautions necessary before maintenance work can be carried out on an induction motor.

(b) state the maintenance that is normally required in such a motor.

(c) Explain how such a motor may run in the wrong direction on restart.

241) With reference to three phase induction motors explain how the following faults may occur and be remedied :

(a) 'burn out'

(b) overheating,

(c) running in wrong direction.

242) (a) Show a diagrammatic sketch of a self excited a.c. generator and explain its operation.

(b) State how two a.c. generators may be brought in parallel safely.

243) (a) Describe with a sketch how a motor may run on both a.c. and d.c.

(b) Mention limitations and uses of such a motor on board ship.

244) (a) State with reasons what type of a.c. motor can be started direct on line and why other types cannot.

(b) Describe a method of starting other than direct on line and justify its use on a particular type of a.c. motor.

245) (a) Give THREE applications of wound-rotor type of induction motor on board ship and justify the reasons for its use.

(b) Give FOUR applications of squirrel cage type of induction motor on board ship justifying the reasons for its use.

(c) Briefly describe the safety fittings provided to protect these motors.

246) (a) Describe the possible effects of dirt accumulating in electrical machines.

(b) Describe suitable procedures for cleaning electrical machines which are heavily contaminated with dirt deposits.

(c) Explain why re-varnishing of electrical machines is carried out and the necessary precautions to be observed.

247) (a) State the advantages of the induction motor over the synchronous motor.

(b) State whether there are any disadvantages.

(c) State TWO suitable applications of each type of motor on board ship justifying the reasons of suitability.

248) (a) State with reasons the instruments necessary for running of an a.c. generator and for its parallel operation.

(b) Explain the necessity for an instrument transformer and state what provisions are made to protect the instruments in the event of insulation breakdown between the primary and secondary circuits.

249) (a) Explain why a current surge may take place in a.c. electrical machinery.

(b) State TWO likely instances of current surge on board ship and the methods of minimizing it.

250) With reference to a a.c. electrical motors define the causes of and remedies for :

(a) overheating,

(b) vibration,

(c) magnetic noise.

251) With reference to the instrumentation required for a.c. generators :

(a) Explain the function of instrument transformers.

(b) Describe the protection necessary to safeguard personnel and instruments if there is a breakdown of insulation between the primary and secondary circuits of instrument transformers.

(c) State with brief reasons, the instruments necessary for parallel operation.

252) (a) Describe briefly the function of commentator rings in electrical machines.

(b) Mention the regular attention necessary to such components and possible dangers if maintenance is neglected.

(c) State the approximate pressures on slip rings brushes and describe briefly how commutator rings may be cleaned.

253) State how the following conditions affect the condition and performance of induction motors :

(a) worn bearings,

(b) dust laden atmosphere,

(c) overloading.

254) (a) Show a diagrammatic sketch of an a.c. generator and explain its operation.

(b) State how two a.c. generators may be brought into parallel operation safely.

255) With reference to three phase induction motors :

(a) define with reasons the type of bearings normally fitted,

(b) Compare the size of the air gap with that of other electrical motors, and

(c) State why such a motor might run in the wrong direction and how the fault would be corrected.

Switchboards

257) (a) State the necessary operations for paralleling an a.c. generator with live busbars.

(b) Explain the precautions taken when paralleling to avoid excessive current surge.

(c) With the aid of a sketch show how two synchronising lamps can be fitted in conjunction with a synchroscope. Indicate whether the lamps are arranged for 'lamps bright' or 'lamps dark' operation.

258) With reference to electrical equipment in areas aboard ships having potentially flammable atmospheres :

(a) explain the hazards involved,

(b) describe one method of rendering the equipment safe,

(c) explain the precautions necessary when maintenance work is carried out.

259) With reference to the instrucmentation required for a.c. generators

(a) Explain the function of instrument transformers.

(b) Describe the protection necessary to safeguard personnel and instruments if there is a breakdown of insulation between the primary and secondary circuits of instrument transformers.

(c) State, with brief reasons, the instruments necessary for parallel operation.

260) (a) State why earth faults on electric cables or equipment should be cleared at the earliest opportunity.

(b) Describe a systematic procedure for locating earth faults aboard ship.

(c) State, with reasons, the most common locations of earth faults aboard ship.

261) (a) State why "dead front" switchboards are required for a.c. systems having voltages to earth greater than 55 V.

(b) Explain how sections of an electrical system aboard ship can be isolated for maintenance work.

(c) Describe the procedure to replace a three phase induction motor with a spare.

262) With reference to cargo pumprooms on oil tankers :

(a) Describe the measures taken to prevent electrical faults on lamp fittings from igniting flammable atmospheres.

(b) Describe the arrangements made to allow lamp replacement or maintenance work to be safely carried out without extinguishing all lamps in the pumproom.

(c) State possible defects to lamp fittings and associated wiring which can render the installation unsafe.

263) With reference to electrical contractors :

(a) Explain how copper contactors are kept free of oxide formations.

(b) Explain why the contact pressure maintained by spring force is

important.

(c) Describe the functions of auxiliary contacts.

264) (a) Explain the necessity of keeping electrical contactors clean, and closed with a firm contact pressure.

(b) Describe briefly the functions of auxiliary contacts.

(c) State how copper contactors are kept free of oxide formations.

265) (a) Explain the meaning of a "dead front" switchboard as against a 'dead' switchboard.

(b) State TWO faults that may develop with copper contactors and how these may be remedied.

(c) State the function of auxiliary contacts.

266) (a) Sketch a circuit breaker as fitted in an a.c. system and explain its operation.

(b) State where and why such circuit breakers are fitted.

(c) Compare the operation of a circuit breaker with a fuse.

(i) Briefly explain how a synchroscope works.

(ii) State the use of a synchroscope on board ship.

(iii) Draw a simple line diagram to explain the use of a synchroscope.

267) (a) Briefly describe the procedure of paralleling an a.c. generator with live busbars explaining the reasons for the precautions.

(b) By a simple diagram show how tow lamps can be fitted in conjunction with a synchroscope for paralleling operation and indicate whether lampls are arranged for 'lamps bright' or 'lamps dark' operation.

268) (a) Explain why 'low voltage' protection is provided in a.c. systems.

(b) Briefly describe how this protection is effected.

269) (a) Differentiate between an 'open type' and a 'dead front' switch board.

(b) Briefly explain how access to switchgear in a dead front board is made.

(c) List precautions necessary before commencing work on any type of switchboard.

Stabilizers, rudders

271) (a) Sketch in detail a bearing designed to transfer the full weight of rudder and stock to ship structure.

(b) Explain why the thrust faces are so contoured.

(c) Explain why a rudder may tend to lift and how this tendency is countered.

272) With reference to rudders explain how:

(a) badly worn pintles can led to rudder stock fracture,

(b) a watertight hollow rudder reduces a ship's deadweight,

(c) offsetting of palms from the axis of the rudder stock does not place an undesirable torque on the pintles.

273) With reference to rudders state :

(a) Why a breached hollow rudder can add to fuel costs,

(b) why excessive pintle clearance should not be tolerated,

(c) why palms are sometimes stepped and fitted bolts used in connecting upper and lower stocks.

274) (a) Sketch in diagrammatic form a stabilizer unit in which the fins retract athwartships into a recess in the hull.

(b) Describe how the extension/retraction sequence is carried out.

(c) Define how the action of fin stabilisers effects steering.

275) (a) Sketch in diagrammatic form a passive tank stabiliser system, labelling the principal components.

(b) Explain how the system illustrated in (a) functions in heavy weather.

(c) State how it is prevented from getting out the phase with ship motion and aggravating roll.

276) (a) Define the purpose of installing twin skeg rudders.

(b) Identify the problems associated with twin rudder installations.

(c) State why skeg or spade rudders are 'free hanging', whilst semi- balanced rudders carry pintles.

277) (a) Sketch in diagrammatic form a stabilizer unit in which the fins fold into a recess in the hull.

(b) Describe how the folding/unfolding sequence is carried out.

(c) Give one advantage and one disadvantage it possesses compared to the non-folding fin stabliser unit.

278) (a) Give reasons why it is essential that the watertight integrity of hollow rudders be maintained.

(b) State why rudder pintle clearance should not be allowed to become too coarse.

(c) State why fitted bolts are used in rudder stock couplings and why the nuts should be regularly checked for tightness.

279) (a) Sketch a rotary vane type steering gear, and itemise the advantages claimed for this type compared with the multiple ram type.

(b) Describe two operational factors which could adversely effect sealing arrangements of a rotary vane steering gear and state how you would try to limit or control theses factors.

280) With reference to ram steering gears :

(a) How are large wave forces on the rudder accommodated,

(b) Explain how the rudder is returned to its original position after being displaced by a large wave without any further action or signal form the bridge.

(h) Discuss the consequences of allowing rudder weardown to become excessive and state one effect that might show that this was happening.

281) (a) Give reasons why it is essential that the watertight integrity of hollow rudders be maintained.

(b) State why rudder pintle clearance should not be allowed to become too course.

(c) State why fitted bolts are used in rudder stock couplings and why the nuts should be regularly checked for tightness.

Propellors, thrusters, etc

283) With reference to keyless propellers explain :

(a) Why keys and key ways have been eliminated,

(b) how angular slip is avoided.

(c) why mounting upon and removal from a propeller shaft requires a different technique than that employed for propellers with keys.

284) Explain with sketches how watertightness of an external seal for a propeller shaft is achieved :

(a) on passage,

(b) during an afloat survey of the propeller shaft in port.

285) Give reasons why each of the following conditions contributes to an increase in propeller slip:

(a) vessel in ballast condition.

(b) heavily fouled hull,

(c) damaged propeller blades.

(d) Explain why astern propeller slip is appreciably greater than ahead slip.

286) (a) Sketch in detail an external seal arrangement for a propeller shaft.

(b) give two reasons for seal failure.

(c) state how the incidence of seal failure can be reduced.

287) (a) Sketch in diagrammatic form the blade actuating mechanism of controllable pitch propellers.

(b) Give a simple description of its operation in changing the pitch from the full ahead to the full astern mode.

(c) State how blade pitch can be altered upon failure of bridge control.

288) With reference to solid propellers state:

(a) how badly damaged blade tips are restored,

(b) why propellers need balancing form time to time,

(c) why intense concentrated heat should not be applied to bosses.

289) With reference to transverse thrust units define :

(a) the primary purpose for their installation,

(b) with reasons where they are usually located,

(c) how reversal of thrust is accomplished,

(d) how thrust can in some cases be directed.

290) (a) State why new or replacement solid propellers should never be permanently mounted on propeller shafts for the first time until compatibility of the tapers, and fit between the keys and keyways, has been verified as satisfactory.

(b) Explain how compatibility of tapers I ensured.

(c) Define the nature of the required fit between keys and keyways, in (i)

291) (a) Give reasons why the Pilgrim nut has greatly facilitated the mounting and unseating of solid propellers on and from shaft tapers.

(b) Sketch a propeller nut of the Pilgrim pattern.

(c) Give a brief explanation of how the Pilgrim nut is used in propeller withdrawal.

292) With reference to controllable pitch propellers :

(a) explain why the blade attitude assumed upon control failure is considered safe,

(b) Describe how the 'fail safe' feature operates,

(c) state how the ship can be maneuvered when the bridge control is out of action.

293) With reference to controllable pitch propellers :

(a) Sketch in diagrammatic form the arrangement whereby the command signal from the bridge is conveyed to the blade actuating mechanism housed in the rotating propeller shaft,

(b) State how the blade actuating mechanism is protected against ingress of sea water,

(c) state how and why upon failure of pitch control the blades assume a particular pitch angle.

294) With reference to solid propellers state why :

(a) great care must be taken when mounting by 'hydraulic push-up' or 'hyfraulic floating' that the propeller does not go beyond the witness marks on the shaft taper,

(b) in spite of correctly mounting the propeller the nut must be properly tightened and locked,

(c) under normal circumstances the boss should be well 'bedded in' to the shaft taper.

295) (a) Sketch in diagrammatic form any type of transverse thrust unit including the power unit, labelling the principal components.

(b) Explain how this unit operates.

(c) Give reasons for its installation in both lone-haul container carriers and short sea trade 'ro ro' ferries.

296) (a) Specify with reasons the conditions to be met when fitting solid propellers to propeller shafts for the first time.

(b) Give reasons why intense, concentrated, heating of propeller bosses should not be employed to facilitate unseating of solid propelellers from their shafts.

(c) State why propeller nuts need to be locked after tightening.

297) (a) Identify the two parts of ships propulsion machinery which usually cause vibration.

(b) State how vibration can adversely effect :-

(i) Electric motors

(ii) Small bare oil pipes

(iii) Holding down arrangements

(iv) Switch boards

(v) Damping arrangements on instruments.<

> (c) A pressure gauge needle vibrates unduly, discuss means that can be taken to reduce this.

298) (a) With reference to an oil lubricated sterntube explain the need for a hydraulic balance.

(b) Why does bearing wear down effect this balance.

(c) Itemise the factors which adversely effect seal life.

(d) If the seals fail how can oil loss be restricted.

299) (a) Give reasons why the Pilgrim nut has greatly facilitated the mounting and unseating of solid propellers on and from shaft tapers.

(b) Sketch a propeller nut of the Pilgrim pattern.

(c) Give a brief explanation of how the Pilgrim nut is used in propeller withdrawal.

300) The tightness of a nut and bolt system might be critical, describe THREE ways in which this tightness may be established with much more certainty than flogging up the nut to old marks.

Corrosion, fouling

302) Define with reasons the main purpose of each of the following practices :

(a) Use of neoprene washers in the connection between aluminium superstructures and ships main structure,

(b) attachment of anodic blocks to the underwater surface of a hull,

(c) external shotblasting and and priming of hull plating.

303) (a) State how larger ship sides valves can be kept from fouling.

(b) State what regular attention is advisable to ensure their easy operation at all times.

(c) Give two advantages and two disadvantages of sluice valves compared with mitre seat valves for use as sea connections.

303) (a) Identify the localities, internally and externally on hull plating, most prone to corrosive action.

(b) Give reasons for this aggressive attack in each of the instances cited in (i)

(c) State how such action can be inhibited in any one of the instances cited in (i)

304) Give a reason for corrosion in each of the following instances :

(a) connection between aluminium superstructure and steel deck,

(b) in crude oil cargo tanks,

(c) Explain how in each case corrosion can be inhibited.

305) (a) Identify the main causes of corrosion in a ship's internal structure.

(b) Define the measures taken to minimise this action.

(c) State what parts of the internal structure are most liable to corrosion.

306) (a) state how freshwater tanks are prepared for inspection.

(b) State how the surface of the steelwork is treated prior to refilling.

(c) Give reasons for the manner of treatment employed in (ii)

(d) Give reasons why fresh water from such tanks is quite suitable for human consumption and yet fresh water produced by evaporation of sea water is not necessarily suitable for such purposes.

307) (a) Explain how steel work in cargo oil tanks is exposed to active wastage.

(b) Identify with reasons those areas most likely to be affected by such action.

(c) Define the various methods employed to minimise corrosion in oil tanks.

308) (a) Identify three different corrosion problems encountered in ship structure.

(b) Define the origins and significance of each

(c) State what precautions are taken to reduce their effects.

309) Describe the reason for corrosion :

(a) at aluminium and steel connections,

(b) in the proximity of the propeller, and

(c) in oil fuel cargo tanks.

Explain in each case how the corrosion can be prevented.

Systems, Safety

311) (a) Draw a line diagram of a bilge suction distribution s dry cargo vessel, showing the disposition of the bra in the various compartments and of the available pump

(b) Give three common reasons for failure to empty bilge

(c) State how each of the faults in (ii) are traced and

312) with reference to the filling of fuel ballast tanks with water ballast explain :

(a) how overpresure in the tanks can occur and what would be the consequences,

(b) the undesirability of slack tanks,

(c) State how each of the faults in (ii) are traced and

313) With reference to ballast systems in dry cargo vessels state with reasons where :

(a) main and branch lines run in relation to the ship's side and tanks respectively,

(b) air and sounding pipes are located in the tanks.

314) Define the main purpose of the following tank and pumping system details :

(a) weighted cocks on tank sounding pipes.

(b) remote operating gear for bilge valves,

(c) ventilation pipes for double bottom tanks,

(d) explain why copper gauze is sometimes fitted to tank ventilation pipes.

315) Sketch and describe a self-contained breathing apparatus. Give two advantages and two disadvantages of this equipment compared to the smoke helmet. State the signal system used when wearing breathing apparatus.

316) (a) Explain how a set of chain lifting gear is maintained in good condition.

(b) Describe how a cumbersome machinery component is lifted from the lower engine room level to the boat deck with the aid of only ship's staff and equipment.

(c) State what precautions requires observance during the operation to ensure maximum safety.

317) (a) Identify the ways, apart from a collision, in which large quantities of sea water can quickly enter the engine room, and

(b) Describe in each case how you would try to either stop or limit this trouble.

(c) What is the likely consequential damage that is likely to occur if the sea water rose to the engine room plates before being stopped.

318) As the second engineer what advice with regard to personal safety would you give to a young engineer about the following :-

(a) Working under the engine room plates

(b) Dismantling a centrifugal pump casing

(c) Renewing a boiler water gauge glass while the boiler was steaming.

(d) Working with portable electric hand tools,

(e) Opening up a steam valve after the main steam stop valve on the boiler has been closed.

319) (a) State what problems arise from the alternate use of double bottom tanks for the carriage of oil fuel and water boiler.

(b) State why such arrangements are sometimes necessary.

(c) Describe how the mixing of fuel and ballast in prevented.

(d) State how legislation on oil pollution is observed.

320) Define with reasons the main purpose of each of the following prc (a) bilge m outside the machinery spaces confined within a central sixty per cent of the ship's breadth.

(b) discharges led overboard from normally inaccessible spaces below freboard decks kept locked shut whilst or voyage.

321) (a) Define the purpose of air pipes associated with double bottom fuel tanks.

State what provisions are made with such air pipes with respect to :

(b) heavy weather,

(c) fire,

(d) bunkering.

322) State with reasons why the following should be encouraged :

(a) tank sounding cocks kept free to operate easily,

(b) tank air pipes kept free form heavy wastage at weather deck level.

(c) extended spindles to bilge valves kept free to operate easily,

(d) trip wires to fuel tank suction valyes kept free from fretting,

(e) wire gauze, as fitted over the mouth of some tank vents, kept unpainted.

323) Enumerate the precautions necessary before entering tanks in which fuel oil has been carried,

List the advantages and disadvantages of using the following when inspecting empty oil fuel tanks :

(a) equipment fitted with a battery or accumulator, and

(b) equipment operated from the ship's electrical system.

324) (a) Before entry into an enclosed space which has previously contained oil it is essential that the atmosphere be tested, identify the tests.

(b) How are the instruments checked to ensure that they are operating normally prior to checking the enclosed space.

(c) With the aid of a sketch describe one of the instruments and state the principle of its operation.

325) State why oxygen deficiencies may occur in certain spaces in ships.

Describe the precautions taken before entry to any recently opened space.

State how and why a bottle is checked before use and explain how the warning is given that a bottle is nearly exhausted.

326) (a) What is the principle behind the fitting of an inert gas system on a tanker.

(b) Why has corrosion been one of the major problems with inert gas and what can be done to limit this problem.

(c) What part in the system does PRESSURE/ VACUUM valves play.

(d) Itemise the major controls fitted to an inert gas system.

327) (a) Describe with the aid of a simple block sketch an inert gas system for a tanker.

(b) Explain the reason why a number of safety features are incorporated in the system.

(c) Discuss briefly the material needs in scrubbing tower design.

General Ship Construction, drydock

329) Define with reasons the purpose of the following ship construction details:

(j) bulbous bow,

(ii) bow flare,

(iii) bilge keels,

(iv) sheer.

330) (a) Define the purpose of cofferdams.

State where cofferdams are most likely to be found in :

(b) dry cargo vessels,

(c) oil tankers.

(d) Identify with reasons the precautions to be observed before and during entry to cofferdams.

331) Give reasoned explanations for the following ship construction details:

(a) weather deck entrances to compartments below freeboard deck provided with sills and water tight doors,

(b) large capacity scuppers with non-return valves located in the enclosed vehicular deck in ro/ro vessels,

(c) watertight doors in subdivision a bulkheads are strictly limited in size and number.

332) Define briefly the construction details peculiar to each of the following types of closure that enables their primary function to be fully realized :

(a) water tight doors,

(b) fire proof doors,

(c) gas tight doors.

(d) State why (i) can perform the function of (ii) and (iii), whereas (ii) and (iii) are restricted solely to their primary function.

333) Describe with sketches the provisions made for draining and / or pumping the following spaces :

(a) 'tween deck spaces,

(b) fore peak tanks,

(c) chain lockers

334) (a) Give reasons why scuppers are generally located in close proximity to superstructure, deckhouses and other weather deck erections, whereas freeing ports are generally located in open areas of the weather deck.

(b) Explain why it is essential that scuppers and freeing ports should function satisfactorily at all times,

(c) State why oil tankers in particular have ship side guard rails abreast cargo tanks for reasons other than personnel safety.

335) (a) Sketch the following types of rolled steel sections in a representative role to stiffen plating :

bulb angle, angle bar, offset-bulb plate, flat bar.

(b) State where in ship's structure these rolled sections are commonly used.

(c) Define with sketches other means used to stiffen large areas of plating.

336) Give a reasoned explanation why:

(a) watertight doors are generally located in machinery spaces, and fire doors in accommodation spaces,

(b) all fire and watertight doors can be closed and opened from either side,

(c) alarms are normally associated with watertight doors only, (d) compared to fire doors, watertight doors are cumbersome in construction and slow in action.

337) (a) Identify four materials used for insulating refrigerated spaces.

(b) Give four qualities which such an insulating material must possess.

(c) Describe with sketches how a refrigerated cold store in insulated.

338) (a) Select and sketch in diagrammatic form a water tight door primarily operated by either electrical or hydraulic power, showing in detail the closing arrangements.

(b) Identify with reasons the various stations from which the door can be closed.

(c) Identify two safety devices incorporated in the actuating system of (i)

339) Make a sketch of a watertight door giving details of the fastening arrangements to show how edge watertightness is maintained.

Describe the procedure adopted for testing two or the following for watertightness :

(a) a watertight door,

(b) a deep tank bulkhead, and

(c) a hold-bulkhead in a dry cargo ship.

340) Describe briefly how freshwater double bottom tanks are cleaned for inspection and how the surface of the steel work should be treated prior to filling.

As Engineer Officer responsible for opening the tank, directing cleaners, inspecting, closing and refilling the tank, state the precautions that should be observed.

341) Suggest with reasons weather 'build up' by welding, patching, cropping or plate replacement is best suited to the following structural defects :

(a) severe pitting at one spot on deck stringer,

(b) external wastage of side plating below scuppers,

(c) extensive wastage of side plating along waterline.

342) (a) Explain why pillars are fitted in ships.

(b) sketch a pillar, showing details of its head and heel attachment.

(c) Discuss whether compressive or tensile stress is the more important stress to which pillars are subjected.

342) Explain how temporary repairs can be made to the following with the equipment normally available at sea :

(a) badly corroded hatch coaming,

(b) fuel oil double bottom tank air pipe broken off at weather deck level.

(c) buckled watertight door frame, and

(d) crack in bulwork plating adjacent to accommodation.

343) (a) Your ship has entered dry dock and it has been decided to remove the tail shaft. Itemize the various stages of this work.

(b) What defects in the tail shaft would you particularly look for.

344) (a) Your ship is in drydock and you have been asked to inspect the anchor chain and its fittings, describe how you would carryout this work.

(b) How would you judge whether or not a shackle should be dismantled for a more thorough inspection.

(c) Make a sketch showing how the anchor chain can be held to prevent undue stress being put on the windlass.

345) (a) Itemize the preparations you would make on a ship about to enter drydock and comment abut the troubles or damage that might occur if the ship was drydocked unprepared.

(b) After the water has been pumped out of the drydock detail the examination you would make on the propeller and rudder.

(c) List any dimensions you would take when doing (b).

346) Your ship has run firmly aground and the main engine has been stopped, describe the steps you would take to start to limit the damage the engine space as much as possible.

347) Describe suitable arrangements for each of the following :

(a) penetration of watertight bulkheads by :

(i) rotating shafting

(ii) ballast pipes, and

(iii) electric cables.

(b) ventilating truck passing a fireproof bulkhead.

Explain how a fire is prevented from spreading along the trunking.

Compressors

349) With reference to an air compressor :

(a) What is may be the first sign of loss of efficiency.

(b) What factors influence efficiency.

(c) If due to some reason or another the quantity of cooling is restricted what will be the effects.

General

350) Describe the locking devices used in the following :

(a) safety valve seat

(b) pump impeller

(c) rope guard on main propeller

(d) holding down botls of heavy machinery

Explain how you would check the effectiveness of (a).

351) (a) Sketch the drive arrangements for an electrically powered windlass and explain how the power can be diverted to one or other of the cable holders.

(b) How is the motor protected against overload.

352) (a) Give 3 reasons why 'blackouts' occur in engine rooms.

(b) Describe in some detail (after stating what type of ship you are dealing with) what needs to be done after a 'blackout' occurs to rectify the situation. Your remarks should be in reasonable order of priority.

353) (a) List the safety devices you would expect to find on a package boiler.

(b) Explain the procedure for testing all the safety devices when the boiler is started.

354) (a) Sketch how a safety valve seat is held in position.

(b) In detail, describe how a boiler safety valve is set after it has been dismantled for inspection.

W T DOORS

355) (a) Describe with the aid of a sketch how a hydraulically operated water tight door works.

(b) Explain the safety features normally fitted.

356) Explain the safety features normally fitted.

(a) Select and sketch in diagrammatic form a watertight door primarily operated by either electrical or hydraulic power, showing in detail the closing arrangements.

(b) Identify with reasons the various stations from which the door can be closed.

(c) Identify two safety devices incorporated in the actuating system.