Marine Engineering Knowledge (Motor)

What is "virtual tappet" in the hydraulically actuated air spring return exhaust valves, and how is it set. Explain why the damage occurs to the seats of the exhaust valves due to furrowing and cutting and how an incident of "valve drop" leading to extensive damage to running gear can occur. (16)

(a) Describe, with the aid of sketches, the procedure for cutting out and "hanging-up" an engine cylinder of a two-stroke crosshead engine in the event of complete failure of the crosshead pin such that the crosshead pin cannot be operated, and no replacement is immediately available. (12)

(b) State, with reasons, the factors which may inhibit starting and limit the operating speed of the engine with a cylinder cut out. (4)

Selective catalytic Reactors (SCR) are being extensively used in marine diesel engines for the compliance of Tier-III NOx emission requirements. Explain various types of SCRs in use with particular focus on the following: (16)

(a) High-Pressure SCRs (HPSCR) vs Low-Pressure SCRs (LPSCR)

(b) SCRs with static mixers.

(c) SCRs installed upstream the turbocharger(s) Vs downstream turbochargers

With reference to main engine starting and reversing:

(a) Define the function of air distributors (5)

(b) Give reasons why air distributors are not fitted to some large direct reversing engines. (3)

(c) Briefly Discuss the potential issues with air distributors and their respective solutions (8)

Misalignment of the main shafting between engine and propeller causes bearing overloads and shaft stress.

(a) State the difficulties associated with checking shaft alignment and the reasons why results are unreliable due to external factor. (5)

(b) Explain with a simple sketch how a bearing load is assessed. (5)

(c) Explain how uneven loading could be rectified. (6)

Discuss the consequences of failure to maintain correct clearances in the case of main diesel engine crankshaft and bottom end bearings. Sketch a bottom end bearing paying particular attention to the arrangement of ensuring uninterrupted flow of oil to the top end bearing. (16)

(a) Compare the advantages of forged and built-up crankshafts with special reference to the magnitude of the stresses in the cranks. (5)

(b) How would you check the deflections by means of a dial gauge through one revolution of the shaft? (4)

(c) How are the readings obtained interpreted? (4)

(d) How is the wear down measured? (3)

Discuss critically the following alternative types of main propelling machinery for installation in a proposed new container ship:

(a) 2 stroke single acting cross head type slow speed engine (8)

(b) 4 stroke single-acting with reverses / reduction gear (8)

(a) Briefly discuss the advantages, disadvantages and working of pulse type cylinder lubrication system. (8)

(b) Explain the process of calculating specific cylinder oil consumption of main engine. (8)

(a) Common rail fuel injection systems have made a comeback in marine diesel engines; The older mechanically controlled systems have been replaced by electronic/hydraulic controlled systems. Describe, with a line diagram any one type of a modern CR system, mentioning the engine type. (8)

(b) Compare the advantages and disadvantage of the Common rail fuel injection systems with the jerk type of injection system. Give examples of their use in modern marine diesel engines. (8)

(a) What is the meaning of "de-rating "of machinery? (5)

(b) Explain the principles behind de-rating a ship propulsion engine as a retro fit and the benefits, thereof. (6)

(c) Can a de-rated engine be run at full power? If yes, under what conditions? (5)

Crankcase oil mist detectors have undergone a lot of changes in recent years. Compare the modern types with multiple sensor units with the traditional single sensor type. where sampling was done sequentially. What is meant be addressable sensors? (16)

Discuss the significance of cylinder lubrication in two stroke diesel engines considering the impact of Annex VI of Marpol 73/78. Explain:

(a) Two level cylinder lubrication incorporated on few diesel engines. (8)

(b) The effect of over and under lubrication on engines. (8)

With regards to modern diesel engines revolution pick up sensor, discuss with suitable diagram the following. (16)

(a) functioning of revolution pick up sensor.

(b) adjustment of pick-up sensor

(c) adjustment of rotary encoder

(d) adjustment of pulse angle offset

With respect to large two stroke crosshead main engines:

(a) Sketch and describe a crosshead designed to prevent or minimize bearing edge loading. (8)

(b) State how the arrangement achieves its purpose. (4)

(c) What would be an acceptable range of bearing clearance for the top end bearing and bottom end bearings of a large two-stroke marine diesel engine. (4)

(a) To improve the power-to-weight ratio of an engine, it is necessary to increase the MEP. Discuss the importance of turbocharger compression ratio in this regard. Why has it become necessary to introduce two-stage turbocharging? (8)

(b) With reference to turbochargers with variable turbine area, explain (8)

(i) Which area is varied

(ii) Why is it varied

(iii) How is it varied

Explain why the following problems occur in turbocharger nozzles, shrouds and blades, their effects on turbocharger operation and remedies: (16)

(a) Build-up of deposits

(b) Hot corrosion

(c) Erosion

(a) Explain fatigue cracking, stating its causes and propagation. (8)

(b) Explain, how poor maintenance and engine overload may contribute to the risk of fatigue cracking of cylinder head holding studs. (8)

With reference to Cylinder Liner lubrication of large two stroke engines:

(a) Outline the problems associated with improper lubrication of the liner and piston assembly of a large slow speed engine. (6)

(b) Describe and state the causes of cloverleafing, and micro-seizure. (6)

(c) List out the composition of a cylinder oil suitable for an engine operating on residual fuel. (4)

(a) Describe with the aid of a sketch the construction of a single collar thrust bearing. (6)

(b) Explain the principle on which it works. (5)

(c) Explain how you would take the essential clearances and explain the significance of each of them. (5)

With regards to modern 4-stroke diesel engine explain the following:

(a) The function of protection ring installed on the upper part of liner. (4)

(b) The modification in fuel injection drive system compared to conventional 4-stroke engine. (4)

(c) Staggering of layout for multi hole nozzles. (4)

(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated. (4)

How are large slow speed engines structured to withstand the following forces?

(a) Forces due to combustion loads. (6)

(b) Guide forces. (5)

(c) Inertia forces. (5)

With reference to piston rings:

(a) State reasons for breakage. How maintenance and engine operation could minimize breakage? (8)

(b) Explain the possible consequences with respect to performance and safety of operating the engine with broken or severely worn piston rings. (8)

(a) Explain how static and dynamic imbalance of crankshafts can be overcome. (5)

(b) Discuss the methods employed to obtain primary, reciprocating balance in an engine and explain why they are not completely successful. (5)

(c) Describe engine additions which may be fitted to overcome problems resulting from primary or secondary imbalance. (6)

(a) Cast Iron welding is a challenging task, give reasons. (8)

(b) What alternative repair methods were employed by engine makers on a cast iron casing of an engine? (8)

With reference to large, fabricated bed plates explain:

(a) With reason, why longitudinal strength and rigidity is important despite the contributions made by ship's structure. (8)

(b) With sketches show how the combustions loads imposed on piston and cylinder heads are transmitted to and absorbed by bed plates. (8)

(a) Sketch and explain a fuel injection pump capable of operating with variable injection timing. (10)

(b) Explain how the fuel injection pump sketched in part (a) changes the timing and quantity of fuel injection. (6)

(a) Explain the possible reasons of Main Engine T/C vibration while operating at a steady speed. (4)

(b) State how the incidence of turbo charger vibration can be minimized. (4)

(c) Explain the action to be taken in order to maintain 2 stroke – engine operation in the event of a out of service turbo charger. (4)

(d) How is the engine operation affected when operated with a by-passed T/C (4)

(a) Sketch a sealing arrangement for an oil lubricated stern tube. (7)

(b) Identify the common forms of seal failure. (3)

(c) State how oil loss due to seal failure can be restricted whilst on Passage. (3)

(d) How the aft bearing is designed to minimize the concentrated load? (3)

(a) Why is the axial clearance of a main thrust bearing an important dimension? (6)

(b) How is this clearance measured? (4)

(c) Describe how the thrust pads are removed for inspection and state what you would look for in particular. (6)

(a) Describe, with the aid of a sketch, a waste heat recovery system for electrical generation using main engine exhaust gas in combined gas/steam turbine systems. (8)

(b) Describe the operation of the waste heat recovery system described in part (a) whilst the associated main engine is running. (8)

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is located in the gas train. (8)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system. (4)

(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works (4)

(a) Explain why highly efficient diesel engines tend to produce more NOx than low performance diesel engines. (5)

(b) Describe, with the aid of a sketch, a Selective Catalytic Reduction (SCR) unit for a marine propulsion diesel engine. (6)

(c) Explain why accurate monitoring of the exhaust gas flows entering and leaving a Selective Catalytic Reduction unit are required and how these readings are used to control the reduction chemical supplied to the SCR unit. (5)

With reference to electronically controlled engines:

(a) Describe how fuel injection quantity and timing is adjusted. (6)

(b) Describe how the exhaust valve timing may be varied. (5)

(c) Describe how starting air valves are regulated. (5)

Sketch and describe the arrangement of a main engine camshaft chain. Describe the repair procedure following fracture of one chain link during operation of the engine. Give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension. (16)

(a) Define the term Torsional Vibration with respect to an engine crankshaft, stating the effect that high levels of such vibration can have on an engine crankshaft. (6)

(b) Explain how engine deterioration influences the risk of Torsional Vibration, stating what can be done to minimise that risk. (6)

(c) Explain TWO possible reasons for the activation of a Torsional Vibration alarm after an engine has been started if there had been no previous history of such an alarm and if no maintenance had been undertaken on the engine whilst it was stopped. (4)

Sketch and show all parts of a two-stroke engine stuffing box. Describe the procedure of overhauling two-stroke engine stuffing box without removing piston. Answer should include all safety precautions and necessary tools used for stuffing box overhaul. (16)

Auxiliary engine components often face demanding service conditions. Analyse how the addition of alloying elements (such as silicon, chromium and manganese) to cast iron influences corrosion resistance, hardness, and thermal stability of these parts. Provide examples of auxiliary engine components that benefit from such alloying. (16)

Express your reactions and state the subsequent investigation you would make if a laboratory report on a used diesel engine lubricating oil sample indicated the presence of appreciable amounts of: (16)

(a) Iron;

(b) Copper;

(c) Antimony and Tin;

(d) Silicon;

(e) n-pentane and toluene insoluble.

With reference to Crankshafts in Marine Diesel Engines:

(a) Describe different types of crankshafts, and highlight their constructional features, materials used, and typical applications. (8)

(b) Compare the advantages and disadvantages of semi-built and solid forged crankshafts with respect to strength, repairability, manufacturing process, and suitability for different engine sizes. (8)

(a) Describe the actions and checks required to ensure that a crosshead main propulsion engine may be operated in a slow steaming condition. (8)

(b) Explain the problems that may arise during a prolonged period of slow steaming. (4)

(c) Explain what actions should be taken before and after the engine is returned to normal operation after a period of slow steaming. (4)

(a) Explain the need for a moment compensator in large two stroke marine engines. With the help of a neat sketch, describe the construction and working principle of a moment compensator. (10)

(b) Discuss the consequences of failure or incorrect functioning of the moment compensator in a two-stroke engine. What checks and maintenance practices are recommended to ensure its reliability? (6)

(a) Define Specific Cylinder Lubricating Oil Consumption (SCLOC) in a two-stroke marine marine diesel engine. Derive the formula for SCLOC and explain the procedure adopted onboard to optimize engine operation. (10)

(b) Discuss the factors affecting SCLOC and explain the procedures adopted onboard to optimize cylinder oil consumption. Include methods used for monitoring and adjusting the cylinder lubrication system. (6)

With regards to modern diesel engine raising the Life Cycle Value (LCV), describe the importance of following: (16)

(a) Low sac volume of Fuel Injection Valve

(b) Fuel valve opening pressure regulation

(c) Contamination of combustion chamber and impact on LCV

(d) Contamination of lube oil and impact on LCV. (16)

With reference to Crankshaft deflections:

(a) Explain why crankshaft deflections are taken. (4)

(b) Write a procedure for the taking of main engine crankshaft deflections. (8)

(c) Explain the action to be taken if some crankshaft deflection readings are outside acceptable limits. (4)

With reference to Cylinder Liner lubrication of large two stroke engines: (16)

(a) Outline the problems associated with improper lubrication of the liner and piston assembly of a large slow speed engine

(b) Describe and state the causes of cloverleafing, and micro-seizure

(c) List out the composition of a cylinder oil suitable for an engine operating on residual fuel.

With reference to bridge control of a large slow speed propulsion engine: (16)

(a) How is starting and reversing achieved?

(b) Investigate and suggest remedial action required if the engine

(i) Fails to turn on air.

(ii) Turns on air but fails to fire on fuel

(iii) Fails to reverse

With regards to modern 4-stroke diesel engine explain the following: (16)

(a) The function of protection ring installed to the upper part of liner.

(b) The moderation in fuel injection drive system compared to conventional 4-stroke engine.

(c) Staggering of layout for multi hole nozzles.

(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated

Sketch and describe the arrangement of a main engine camshaft chain. Describe the repair procedure following fracture of one chain link during operation of the engine, give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension. (16)

With reference to piston rings:

(a) State reasons for breakage.

(b) How maintenance and engine operation could minimize breakage?

(c) Explain the possible consequences with respect to performance and safety of operating the engine with broken or severely worn piston rings.

(a) Explain how static and dynamic imbalance of crankshafts can be overcome. (5)

(b) Discuss the methods employed to obtain primary, reciprocating balance in an engine and explain why they are not completely successful. (5)

(c) Describe engine additions which may be fitted to overcome problems resulting from primary or secondary imbalance. (6)

(a) Cast iron welding is a challenging task, give reasons. (8)

(b) What alternative repair methods were employed by engine makers on a cast iron casing of an engine? (8)

(a) Sketch a sealing arrangement for an oil lubricated stern tube. (4)

(b) Identify the common forms of seal failure. (4)

(c) State how oil loss due to seal failure can be restricted whilst on Passage. (4)

(d) How the aft bearing is designed to minimize the concentrated load? (4)

(a) Sketch and explain a fuel injection pump capable of variable injection timing. (10)

(b) Explain how the fuel injection pump sketched in part (a) changes the timing and quantity of fuel injection. (6)

With reference to Cylinder Liner lubrication of large two stroke engines: (16)

(a) Outline the problems associated with improper lubrication of the liner and piston assembly of a large slow speed engine

(b) Describe and state the causes of cloverleafing, and micro-seizure

(c) List out the composition of a cylinder oil suitable for an engine operating on residual fuel.

With reference to bridge control of a large slow speed propulsion engine: (16)

(a) How is starting and reversing achieved?

(b) Investigate and suggest remedial action required if the engine

(i) Fails to turn on air

(ii) Turns on air but fails to fire on fuel

(iii) Fails to reverse

With regards to modern 4-stroke diesel engine explain the following. (16)

(a) The function of protection ring installed on the upper part of liner.

(b) The moderation in fuel injection drive system compared to conventional 4-stroke engine.

(c) Staggering of layout for multi hole nozzles.

(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated

Sketch and describe the arrangement of a main engine camshaft chain. Describe the repair procedure following fracture of one chain link during operation of the engine, give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension. (16)

With reference to piston rings: (16)

(a) State reasons for breakage.

(b) How maintenance and engine operation could minimize breakage?

(c) Explain the possible consequences with respect to performance and safety of operating the engines with broken or severely worn piston rings.

(a) Explain how static and dynamic imbalance of crankshafts can be overcome. (5)

(b) Discuss the methods employed to obtain primary, reciprocating balance in an engine and explain why they are not completely successful. (5)

(c) Describe engine additions which may be fitted to overcome problems resulting from primary or secondary imbalance. (6)

(a) Cast Iron welding is a challenging task, give reasons. (8)

(b) What alternative repair methods were employed by engine makers on a cast iron casing of an engine? (8)

(a) Sketch a sealing arrangement for an oil lubricated stern tube. (4)

(b) Identify the common forms of seal failure. (4)

(c) State how oil loss due to seal failure can be restricted whilst on Passage. (4)

(d) How the aft bearing is designed to minimize the concentrated load? (4)

With respect to fuel injection system of diesel engines,

(a) What is the purpose of VIT? (6)

(b) How is the end of injection controlled in a 2 stroke propulsion engine and 4 stroke medium speed auxiliary engine? (6)

(c) Explain the purpose of a draw card. (4)

With respect to a turbo-charging a 2-stroke main propulsion diesel engine:

(a) What is the purpose of auxiliary blower?

(b) What are the safeties provided for the scavenge air receiver?

(c) Why do we require scavenge air cooler?

A Crankshaft of a two-stroke engine undergoes several types of stresses during the operation of the engine. Explain these types of stresses and possible effect they have on the crank shaft. Also explain how these stress and their effects are taken care of during the design and operation of the engine.

(a) What are the advantages of thin shell bearings over white metal bearing used in marine diesel engines?

(b) How are the thin shells prevented from rotating inside the bearing cage when the engine is running?

(c) What is importance of axially locating the thin shell bearing and how it is done?

Draw and explain the working of a typical Diesel Electrical Propulsion system. Also explain the advantages and disadvantages of such a system over the conventional two stroke engine propulsion system.

With respect to a 2-stroke main propulsion diesel engine starting air system,

(a) Explain the starting air overlap?

(b) What is the starting air timing for one cylinder?

(c) What is slow turning arrangement and what is the purpose?

With respect to fuel injection system of diesel engines,

(a) What is the purpose of VIT?

(b) How is the end of injection controlled in a 2 stroke propulsion engine and 4 stroke medium speed auxiliary engine?

(c) Explain the purpose of a draw card.

With reference to a 4 stroke medium speed auxiliary diesel engine,

(a) Describe with a simple sketch bottom end bearing assembly.

(b) What is the purpose of serrations provided on the piston rod and bearing keep?

(c) What special features are provided on the connecting rod bolts?

With reference to an electro-hydraulic speed governor fitted to an auxiliary diesel engine driving an alternator,

(a) With the aid of a simple sketch, explain the speed droop mechanism.

(b) What are the differences between the isochronous and droop governors?

Explain the working principle of a Variable Geometry Turbocharger (VGT) and how it differs from a fixed geometry turbocharger. How is the Variable Geometry Turbochargers (VGTs) important for marine engines and how they help maintain the right mix of air and fuel at different engine power levels.

Crankshaft of a 2-stroke engine goes through several types of stresses during the operation of the engine. Explain these types of stresses and possible effect of them on the crank shaft and how are these stresses taken care of in the crankshaft. (16)

With regards to modern 4-stroke diesel engine explain the following. (16)

(a) The function of protection ring installed on the upper part of liner.

(b) The modification in fuel injection drive system compared to conventional 4-stroke engine.

(c) Staggering of layout for multi hole nozzles.

(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated.

With respect to the refrigeration system on board vessels, answer the following.

(a) Why are some TEVs fitted with an external equalising connection? (6)

(b) What is the purpose of a back pressure valve. What will the effect if it leaks? (5)

(c) How does an electronic TEV function. (5)

Electronically controlled marine diesel engines are said to provide advantages over the traditional engines in the following areas: (16)

(a) Improved fuel economy

(b) Emission control

(c) Engine response during manoeuvring, especially crash movements.

Explain how these are achieved.

With reference to main Thrust bearing of the pivoting pad type, explain with sketches where necessary (16)

(a) The principle of operation of the bearing.

(b) The critical clearances and why they are critical?

(c) How these clearances are adjusted?

(d) Why such bearings sometime overheat although the clearances are adequate?

(e) How is the lubrication film between faces of collar and thrust pad maintained?

It is common practice to plot in a graphical form the wear of a cylinder liner against the number of hours it has been in operation. When this is done it is often noticed that some scatter exists between the plotted points after a few wear figures have been recorded.

What is the reason for the scatter and how can the wear rate be shown in a more acceptable form? How would you forecast the length of life for a cylinder liner? (16)

(a) Describe, with the aid of a sketch, an external system for reducing engine NOx emissions, explaining the chemistry of the process (6)

(b) Explain why Urea is used in the Selective Catalytic Reduction process instead of ammonia. (5)

(c) Explain why the exhaust gas quality must be monitored before and after the Selective Catalytic Reduction unit, stating how such monitoring influences operation of the SCR unit (5)

(a) Explain how static and dynamic imbalance of crankshafts can be overcome. (5)

(b) Discuss the methods employed to obtain primary, reciprocating balance in an engine and explain why they are not completely successful. (5)

(c) Describe engine additions which may be fitted to overcome problems resulting from primary or secondary imbalance. (6)

(a) Cast iron welding is a challenging task, give reasons. (8)

(b) What alternative repair methods were employed by engine makers on a cast iron casing of an engine. (8)

(a) With the aid of a block diagram describe the operation of an electronic governor fitted to an auxiliary diesel engine. (8)

(b) Engines fitted with an electronic governor may behave erratically during load changes. Explain the possible causes. (8)

(a) State, with reasons, the properties required for a cylinder lubricant for a main engine operating on HFO. (8)

(b) Describe, with the aid of a sketches, an electronically controlled cylinder lubrication system, stating how the timing and quantity of cylinder lubricant is regulated and set (8)

(a) Define the term Torsional Vibration with respect to an engine crankshaft, stating the effect that high levels can have on an engine crankshaft. (6)

(b) Explain how engine deterioration influences the risk of Torsional Vibration, stating what can be done to minimise that risk. (5)

(c) Explain TWO possible reasons for the activation of a Torsional Vibration alarm when an engine has been started if there had been no previous history of such an alarm and if no maintenance had been undertaken on the engine whilst it was stopped. (5)

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve unit, explaining its purpose and indicating where it is located in the gas train (6)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system (5)

(c) State why pilot injection must be provided when burning fuel gas, explaining ho a pilot injection system works (5)

(a) Identify the factors, which could be responsible for initiation and propagation of explosions in air starting systems. (4)

(b) Explain how the possibility of an explosion in an air start system is minimized. (4)

(c) Describe the devices required for air start systems, which are intended to dissipate the energy of an explosion. (4)

(d) Suggest why one type of safety addition, although appearing to operate correctly, may not prevent a severe air start line explosion and loss of life. (4)

Give a list of the properties or test by which distillate and blended fuels may be specified or decisions be made on their fitness for use. Name the properties or constituents that may be found in a blended fuel having a high viscosity and high carbon content. Explain how they may cause problems in engine operation. (16)

With reference to medium speed engine cylinder liners:

(a) Explain the cause and effects of polishing or glazing;

(b) Sketch and describe fitting of an anti-polishing ring in the liner.

(c) Explain the action of anti-polishing ring during the operation of the engine

(a) Briefly describe the cause and effects of bacterial attack of lubricating oil. (8)

(b) Bacterial activity has been detected in the lubricating oil of the main engine fitted in the ship aboard which you are serving as Second Engineer. Write a letter to the owner/operator of the ship indicating the action you intend taking and offer suggestions with respect to the avoidance of future incidents. (8)

(a) Why is the axial clearance of a main thrust bearing an important dimension? (5)

(b) How is this clearance measured? (5)

(c) Describe how the thrust pads are removed for inspection and state what you would look for in particular. (6)

(a) Explain the possible reasons of Main Engine T/C vibration while operating at a steady speed.

(b) State how the incidence of turbo charger vibration might be minimised

(c) Explain the action to be taken in order to maintain 2 stroke engine operation in the event of a turbo charger having to be taken out of service

(d) How is the engine operation affected when operated with a by-passed T/C

(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.

(d) How the aft bearing is designed to minimize the concentrated load?

(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.

Describe a three element feed water controller (i.e regulator) measuring steam flow, drum level and feed water flow and explain how a unity relationship is maintained between the three variables.

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is located in the gas train.

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system.

(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works.

(a) Explain why highly efficient diesel engines tend to produce more NOx than low performance diesel engines.

(b) Describe, with the aid of a sketch, a Selective Catalytic Reduction (SCR) unit for a marine propulsion diesel engine.

(c) Explain why accurate monitoring of the exhaust gas flows entering and leaving a Selective Catalytic Reduction unit are required and how these readings are used to control the reduction chemical supplied to the SCR unit.

With reference to electronically controlled engines:

(a) Describe how fuel injection quantity and timing is adjusted.

(b) Describe how the exhaust valve timing may be varied.

(c) Describe how starting air valves are regulated.

Sketch and describe the arrangement of a main engine camshaft chain. Describe the repair procedure following fracture of one chain link during operation of the engine. give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension.

(a) Define the term Torsional Vibration with respect to an engine crankshaft, stating the effect that high levels can have on an engine crankshaft.

(b) Explain how engine deterioration influences the risk of Torsional Vibration, stating what can be done to minimise that risk.

(c) Explain TWO possible reasons for the activation of a Torsional Vibration alarm after an engine has been started if there had been no previous history of such an alarm and if no maintenance had been undertaken on the engine whilst it was stopped.

With respect to a turbo-charging a 2-stroke main propulsion diesel engine:

(a) What is the purpose of auxiliary blower? (5)

(b) What are the safeties provided for the scavenge air receiver? (6)

(c) Why do we require scavenge air cooler? (6)

With respect to a 2 -stroke main propulsion diesel engine draw and explain the following: (16)

(a) How the various sections of exhaust manifold connected together for the main engine?

(b) What is the arrangement for thermal expansion of different sections of the manifold?

(c) What is the arrangement in the exhaust manifold to prevent broken pieces of piston rings entering turbine of the T/C?

Why is it necessary to cool the cylinder head covers and cylinder liners and pistons of slow and medium speed engines? What are the different cooling mediums used for cooling slow and medium speed Engines explain with reasons? (16)

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is in the gas train. (6)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system. (5)

(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works? (5)

While operating at Sea during rough weather conditions, fire sparks have been observed coming out from the funnel of your vessel. On investigation, it has been observed that the fuel contains considerable quantity of water and sludge. As the Second engineer of the vessel. Explain:

(a) Immediate actions taken to rectify the problem. (8)

(b) Precautions you take to avoid recurrence of this type of problem. (8)

With respect to Air Starting systems for 2 stroke diesel engines: (16)

(a) Sketch and describe Main Engine starting air distributor.

(b) List the safety devices and interlocks incorporated in main engine air starting system and state the purpose of each.

With Respect to Main Engine Turbochargers: (16)

(a) Explain why cleanliness throughout the turbochargers system is critical to engine performance.

(b) Describe an in-service cleaning procedure for gas and airsides of a turbocharger indicating safety precautions to be observed.

State the probable engine defects and rectifying action needed if the following conditions are indicated on a single unit of a large two-stroke marine diesel engine having seven units. State any additional information which might be of help in forming an opinion. (16)

(a) Increased exhaust temperatures.

(b) Reduced exhaust temperature.

(c) Reduction in jacket cooling water outlet temperature.

(d) Increase in jacket cooling water return temperature.

(a) To improve the power-to-weight ratio of an engine, it is necessary to increase the Mean effective pressure. Discuss the importance of turbocharger compression ratio in this regard. Why has it become necessary to introduce two-stage turbocharging?

(b) With reference to turbochargers with variable turbine area, explain

(i) Which area is varied

(ii) Why is it varied

(iii) How is it varied

With Respect to a turbocharged 2-Stoke Main Propulsion Diesel Engine:

(a) What is the purpose of Auxiliary Blower. (5)

(b) What are the safeties provided for the scavenge air receiver. (6)

(c) Why do we require scavenge air cooler? (6)

With reference to the burning of heavy residual fuel in the main engine:

(a) State with reasons FOUR modifications which need to be made as compared with the same engine burning distillate fuels. (8)

(b) State with reasons SIX properties you would require seeing in the specification for residual fuel indicating the effect EACH of these properties might have with respect to the storage and burning of the fuel. (8)

(a) Explain why variable exhaust valve closing can be advantageous in the operation of large slow speed main engines. (6)

(b) Explain, with the aid of a sketch, how variable exhaust valve closing is achieved. (6)

(c) Explain how high impact is avoided as the valve closes. (4)

(a) Enumerate the causes of vibration in diesel machinery and shafting. (5)

(b) Describe procedures by which it may be reduced by operating personnel, suitable design and devices. (6)

(c) State the possible effects of vibration on machinery and crewmembers. (5)

(a) Describe how propeller shaft/stern bearing clearance is measured. (4)

(b) Identify with reasons the major factors which substantially determine the range of permissible clearance. (4)

(c) State with reasons what parts of propeller shafts should receive particularly close inspection upon withdrawal of such shafts for survey. (4)

(d) State why some propeller shafts require less frequent inspection than others. (4)

Sketch and show all parts of a two-stroke engine stuffing box. Describe the procedure of overhauling two stroke engine stuffing box, without removing piston. All safety precautions and proper tools used for overhaul to be mentioned. (16)

(a) What is the purpose of the main thrust bearing? (4)

(b) When checking the main thrust bearing, what dimensional checks would be necessary? (4)

(c) How is a thrust bearing cooled? (4)

(d) Describe, with a sketch, the special chocking arrangements normal to thrust bearing. (4)

With reference to an engine air starting system

(a) Explain why a slow turning is fitted. (4)

(b) State, with reasons, when a slow turning system operates. (6)

(c) Describe, with the aid of a sketch, an air starting system, explaining how the slow turning system operates. (6)

(a) Explain why top bracing is used for large crosshead engines. (4)

(b) Describe, with the aid of a sketch, a hydraulic top bracing unit for a large crosshead engine indicating where the top bracing is fitted and how it operates. (6)

(c) Write instructions for the checking of a large crosshead engine top bracing system and a holding down system. (6)

What is the meaning of "de-rating "of machinery?

(a) Explain the principles behind de-rating a ship propulsion engine as a retro fit. And the benefits (8)

(b) Can a de-rated engine be run at full power? If yes, under what conditions? (8)

(a) Explain fatigue cracking, stating its causes and propagation. (8)

(b) Explain, how poor maintenance and engine overload may contribute to the risk of fatigue cracking of cylinder head holding studs. (8)

Sketch and describe the types combustion cycles. Explain the application of each cycle with advantages and disadvantages. (16)

Periodical Lubricating Oil Analysis, its correct interpretation and corrective measures are of critical significance for the maintenance of marine machineries. With reference to the modern analysis techniques employed for the condition of L.O. discuss the following: (16)

(a) Elemental (Spectrometric) Analysis

(b) Fourier Transform Infrared (FTIR) Spectroscopy

(c) Particle Count

(d) Base Number Vs Acid Number

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is in the gas train. (6)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system. (5)

(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works? (5)

(a) Briefly State and describe the various heat treatment processes applied to cast iron main engine components. (4)

(b) How do these treatments modify the microstructure and mechanical properties of the components? (6)

(c) Provide examples of how heat treatment can improve wear resistance, strength, and service life in main engine parts. (6)

With reference to behaviour of fabricated bed plates and frames in services:

(a) Identify various forces imposed simultaneously upon them (6)

(b) Explain how engine structure withstands these forces (5)

(c) State how these forces are transferred to ship's structure (5)

What is slow steaming & how it's achieved without engine modification? Enumerate various operational issues with slow steaming. How such operational issues can be dealt with? (16)

(a) To improve the power-to-weight ratio of an engine, it is necessary to increase the mep. Discuss the importance of turbocharger compression ratio in this regard. Why has it become necessary to introduce 2 stage turbocharging? (8)

(b) With reference to turbochargers with variable turbine area, explain (8)

(i) Which area is varied

(ii) Why is it varied

(iii) How is it varied

Sketch and show all parts of a two stroke engine stuffing box. Describe the procedure of overhauling two stroke engine stuffing box, without removing piston. Answer should include all safety precautions and necessary tools used for stuffing box overhaul. (16)

NOx Tier – III requirements are getting mandatory as per MARPOL Annex VI. In this context, briefly explain the following:

(a) Working principles and Components in a SCR system. (6)

(b) Operational sequence of a NOx control SCR plant. (5)

(c) Operational difficulties in SCR system. (5)

Express your reactions and state the subsequent investigation you would make if a laboratory report on a used diesel engine oil sample indicated the presence of appreciable amounts of:

(a) Iron;

(b) Copper;

(c) Antimony and Tin;

(d) Silicon;

(e) n-pentane and toluene insoluble.

(a) Describe the different types of crankshafts used in marine diesel engines. Highlight their constructional features, materials used and typical applications. (8)

(b) Compare the advantages and disadvantages of semi-built and solid forged crankshafts with respect to strength, repairability, manufacturing process and suitability for different engine sizes. (8)

(a) Describe the actions and checks required to ensure that a crosshead main propulsion engine may be operated in a slow steaming condition. (8)

(b) Explain the problems which may arise during a prolonged period of slow steaming. (4)

(c) Explain what actions should be taken before and after the engine is returned to normal operation after a period of slow steaming. (4)

(a) Explain the need for a moment compensator in large two-stroke marine engines. With the help of a neat sketch, describe the construction and working principle of a moment compensator. (10)

(b) Discuss the consequences of failure or incorrect functioning of the moment compensator in a two-stroke engine. What checks and maintenance practices are recommended to ensure its reliability? (6)

(a) Define Specific Cylinder Lubricating Oil Consumption (SCLOC) in a two-stroke marine diesel engine. Derive the formula for SCLOC and explain the procedure for calculating it during normal engine operation. (10)

(b) Discuss the factors affecting SCLOC and explain the procedures adopted onboard to optimize cylinder oil consumption. Include methods used for monitoring and adjusting the cylinder lubrication system. (6)

With regards to modern diesel engine raising the Life Cycle Value (LCV), describe the importance of following. (16)

(a) Low Sac Volume of Fuel Injection Valve

(b) Fuel valve opening pressure regulation

(c) Contamination of combustion chamber and impact on LCV.

(d) Contamination of lube oil and impact on LCV.

With reference to Modern Diesel Engine describe the features of High-pressure Miller cycle and discuss the following.

(a) Reduction in Air Temperature due to Miller cycle

(b) Recovery of Pressure in the Combustion chamber during the Miller cycle

(c) Effect of Miller Cycle on specific fuel consumption and NOx emission.

(d) The impact on various parameters during low load operation using Miller Cycle

With reference to main engine with tie rod explain:

(a) Function (3)

(b) Effect on main engine in case slack (3)

(c) Identifying slackness (3)

(d) Material (3)

(e) Tightening procedure (4)

(a) State, with reasons, the properties required for a cylinder lubricant for a main engine operating on HFO (8)

(b) Describe, with the aid of a sketch, an electronically controlled cylinder lubriction system, stating how the timing and quantity of cylinder lubricant is regulated and set (8)

(a) Define the term Torsional Vibration with respect to an engine crankshaft, stating the effect that high levels can have on an engine crankshaft (6)

(b) Explain how engine deterioration influences the risk of Torsional Vibration, stating what can be done to minimise that risk (5)

(c) Explain TWO possible reasons for the activation of a Torsional Vibration alarm after an engine has been started if there had been no previous history of such an alarm and if no maintenance had been undertaken on the engine whilst it was stopped (5)

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve unit, explaining its purpose and indicating where it is located in the gas train (6)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system (5)

(c) State why pilot injection must be provided when burning fuel gas, explaining ho a pilot injection system works (5)

(a) Identify the factors, which could be responsible for initiation and propagation of explosions in air starting systems. (4)

(b) Explain how the possibility of an explosion in an air start system is minimized. (4)

(c) Describe the devices required for air start systems, which are intended to dissipate the energy of an explosion. (4)

(d) Suggest why one type of safety addition, although appearing to operate correctly, may not prevent a severe air start line explosion and loss of life. (4)

Give a list of the properties or test by which distillate and blended fuels may be specified or decisions be made on their fitness for use. Name the properties or constituents that may be found in a blended fuel having a high viscosity and high carbon content. Explain how they may cause problems in engine operation. (16)

Evaluate the influence of the following factors upon cylinder and piston ring wear rates. (16)

(a) Position of rings in relation to piston crown,

(b) Spread and proximity of coolant passages from liner wall

(c) Flow rate and specific heat of coolant

(d) Chromium plating of ring faces

(a) (i) Describe with the aid of a sketch, one section of a large slow speed engine crankshaft which has been assembled by shrinkage of webs onto journal pins. (4)

(ii) Explain how a five degree twist might be caused to a shaft assembled by shrinkage (4)

(b) State the possible effects of a five-degree twist in the crankshaft assembly and draw conclusions as to whether the engine should be operated and any adjustments that may be necessary for continued operation. Assume that the incident has occurred at a port with no repair facilities. (8)

(a) Why is the axial clearance of a main thrust bearing an important dimension? (5)

(b) How is this clearance measured? (5)

(c) Describe how the thrust pads are removed for inspection and state what you would look for in particular. (6)

What is the meaning of 'de-rating' of machinery?

(a) Explain the principles behind de-rating a ship propulsion engine as a retro fit. And the benefits. (8)

(b) Can a de-rated engine be run at full power? If yes, under what conditions? (8)

(a) Explain fatigue cracking, stating its causes and propagation. (8)

(b) Explain, how poor maintenance and engine overload may contribute to the risk of fatigue cracking of cylinder head holding studs. (8)

Crankcase oil mist detectors have undergone a lot of changes in recent years.

Compare the modern types with multiple sensor units with the traditional single sensor type, where sampling was done sequentially. What is meant be addressable sensors. (16)

Periodical Lubricating Oil Analysis. Its correct interpretation and corrective measures are of critical significance for the maintenance of marine machineries. With reference to the modern analysis techniques employed for the condition of L.O, discuss the following: (16)

(a) Elemental (Spectrometric) Analysis

(b) Fourier Transform Infrared (FTIR) Spectroscopy

(c) Particle Count

(d) Base Number Vs Acid Number (16)

With reference to LNG diesel engine installations:

(a) Describe, with the aid of a sketch, a Gas Valve Unit, explaining its purpose and indicating where it is in the gas train. (6)

(b) Explain why ventilation and inert gas systems must be installed with the engine fuel gas system. (5)

(c) State why pilot injection must be provided when burning fuel gas, explaining how a pilot injection system works? (5)

(a) Sketch a typical power indicator card for a slow speed marine diesel engine. (8)

(b) Explain how the card may be used to assess the power developed in the cylinder. (8)

With reference to behaviour of fabricated bed plates and frames in services:

(a) Identify various forces imposed simultaneously upon them (6)

(b) Explain how engine structure withstands these forces (5)

(c) State how these forces are transferred to ship's structure (5)

What is slow steaming & how it's achieved without engine modification? Enumerate various operational issues with slow steaming. How such operational issues can be dealt with? (16)

(a) To improve the power-to-weight ratio of an engine, It is necessary to increase the MEP. Discuss the importance of turbocharger compression ratio in this regard. Why has it become necessary to introduce two-stage turbocharging? (8)

(b) With reference to turbochargers with variable turbine area, explain (8)

(i) Which area is varied

(ii) Why is it varied

(iii) How is it varied

With respect to large two stroke crosshead main engines. (16)

(a) Sketch and describe a crosshead designed to prevent or minimize bearing edge loading.

(b) State how the arrangement describes achieves its purpose

(c) What would be an acceptable range of bearing clearance for the top end bearing and bottom end bearings of a large two-stroke marine diesel engine.

With regards to modern 4-stroke diesel engine explain the following: (16)

(a) The function of protection ring installed on the upper part of liner.

(b) The moderation in fuel injection drive system compared to conventional 4-stroke engine.

(c) Staggering of layout for multi hole nozzles.

(d) Effect of swirl and squish during the combustion process and how swirl and squish is generated

With respect to the refrigeration system on board vessels, answer the following:

(a) Why are some TEVs fitted with an external equalising connection? (6)

(b) What is the purpose of a back pressure valve. What will be the effect if it leaks? (5)

(c) How does an electronic TEV function. (5)

Electronically controlled marine diesel engines are said to provide advantages over the traditional engines in the following areas

(a) Improved fuel economy (6)

(b) Emission control (5)

(c) Engine response during manoeuvring, especially crash movements. (5)

Explain how these are achieved.

With reference to main Thrust bearing of the pivoting pad type, explain with sketches where necessary: (16)

(a) The principle of operation of the bearing

(b) The critical clearances and why they are critical?

(c) How these clearances are adjusted

(d) Why such bearings sometime overheat although the clearances are adequate?

(e) How is the lubrication film between faces of collar and thrust pad maintained?

It is common practice to plot in a graphical form the wear of a cylinder liner against the number of hours it has been in operation. When this is done it is often noticed that some scatter exists between the plotted points after a few wear figures have been recorded. What is the reason for the scatter and how can the wear rate be shown in a more acceptable form? How would you forecast the length of life for a cylinder liner? (16)

(a) Describe, with the aid of a sketch, an external system for reducing engine NOx emission, explaining the chemistry of the process (6)

(b) Explain why Urea is used in the selective catalytic reduction process instead of ammonia. (5)

(c) Explain why the exhaust gas quality must be monitored before and after the selective catalytic reduction unit, stating how such monitoring influences operation of the SCR unit. (5)