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HK Engine Operator Grade 3 study materials
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HK Engine Operator Grade 3 practice questions

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Question 1Marine engine operation and watchkeeping

During an engine room watch, the duty engineer notices the main engine fuel oil supply pressure has fallen below the normal running band while the engine load is steady. What is the most appropriate immediate action?

  1. Investigate the fuel supply system and confirm the cause before the pressure drops further Correct answer.
  2. Increase engine load to raise the fuel pump output
  3. Reduce the fuel oil temperature setpoint to thin the fuel
  4. Open the fuel oil filter bypass and continue the voyage without logging

Explanation

A falling fuel supply pressure at steady load indicates a developing fault such as a choked filter, pump wear, or a leaking suction line, and must be investigated promptly. Raising load or bypassing filtration without diagnosis risks fuel starvation, injector damage, or a blackout. The reading should be logged and the chief engineer informed as the situation develops.

Question 2Marine engine operation and watchkeeping

Which parameter is normally monitored to confirm that the main engine cylinder lubrication is functioning correctly on a large two-stroke diesel engine?

  1. Turbocharger rotor speed
  2. Jacket cooling water header pressure
  3. Cylinder liner temperature trend and scavenge drain inspection Correct answer.
  4. Main engine turning gear interlock status

Explanation

Cylinder lubrication condition is assessed from liner temperature trends and from inspecting scavenge space drains for excessive or abnormal oil carry-over. Turbocharger speed reflects scavenge air delivery rather than cylinder oil feed. Jacket water pressure relates to the cooling circuit, and the turning gear interlock is a safety device unrelated to lubricator performance.

Question 3Marine engine operation and watchkeeping

The engine room is unmanned overnight and the machinery space is classed for periodically unattended operation. Which arrangement is required for the bilge high-level alarm?

  1. It only needs to be tested at the annual survey
  2. It can be replaced by a manual sounding routine each watch
  3. It must sound an alarm on the bridge and at the engineers' public spaces Correct answer.
  4. It only needs to operate a local indicator in the engine room

Explanation

For periodically unattended machinery spaces the bilge high-level alarm must be extended to the bridge and to the accommodation or public spaces where engineers are likely to be. A local-only indicator is useless when nobody is in the space. Manual sounding does not substitute for the required automatic alarm, and testing frequency does not remove the alarm requirement.

Question 4Marine engine operation and watchkeeping

During a routine watch round, the duty engineer finds the main engine air start receiver pressure has dropped below the minimum needed for starting. What is the correct response?

  1. Open the receiver drain and leave it open to vent moisture
  2. Investigate the compressor and drain the receiver, then restore pressure before any manoeuvring Correct answer.
  3. Switch the starting air over to the control air system
  4. Isolate the starting air and continue manoeuvring on fuel alone

Explanation

Starting air pressure must be maintained above the minimum for the expected number of starts; a low receiver indicates a compressor fault, leaking valve, or excess condensate. The engineer should find and correct the cause, drain condensate, and restore pressure before manoeuvring is required. Manoeuvring without adequate starting air leaves the vessel unable to respond to bridge orders.

Question 5Marine engine operation and watchkeeping

What is the primary purpose of the crankcase oil mist detector on a medium-speed diesel engine?

  1. To control the crankcase ventilation fan speed automatically
  2. To detect a rising oil mist concentration that indicates an overheated bearing or hot spot Correct answer.
  3. To monitor the crankcase oil level against the sight glass
  4. To measure the viscosity of the crankcase oil during operation

Explanation

An oil mist detector responds to an increase in suspended oil mist in the crankcase, which is an early warning of a hot spot such as an overheating bearing or piston. Early detection allows the engine to be stopped before a crankcase explosion develops. Viscosity, level, and ventilation control are handled by separate devices.

Question 6Marine engine operation and watchkeeping

A duty engineer is about to hand over the watch. Which action best satisfies the requirement for a proper watch handover?

  1. Brief the relieving engineer on machinery condition, ongoing work, and outstanding defects before leaving Correct answer.
  2. Finish the logbook entry after the relieving engineer has taken over
  3. Leave a note on the console and depart once the relieving engineer arrives
  4. Hand over only after the chief engineer has signed the logbook

Explanation

A proper handover requires a verbal briefing covering the state of all machinery, work in progress, defects, and any abnormal readings, so the relieving engineer assumes the watch fully informed. Leaving a note or deferring the logbook does not transfer situational awareness. Chief engineer sign-off is not a condition of routine watch handover.

Question 7Marine engine operation and watchkeeping

Which condition most directly indicates that the main engine scavenge air cooler is fouled on the air side?

  1. Increasing jacket cooling water outlet temperature
  2. Decreasing fuel oil viscosity at the injector
  3. Rising scavenge air temperature with unchanged cooling water conditions Correct answer.
  4. Falling exhaust gas temperature after the turbocharger

Explanation

Air-side fouling reduces heat transfer, so the scavenge air outlet temperature rises even when cooling water flow and temperature are normal. Exhaust gas temperature after the turbocharger tends to rise rather than fall with reduced air density. Jacket water and fuel viscosity are governed by other systems and do not indicate air cooler fouling.

Question 8Marine engine operation and watchkeeping

Which document must be consulted to confirm the correct warm-up procedure for the main engine before departure?

  1. The last port state control inspection report
  2. The bunker delivery note for the previous stem
  3. The manufacturer's operating manual and the vessel's planned maintenance and instruction procedures Correct answer.
  4. The engine room spare parts inventory

Explanation

Warm-up requirements such as jacket water temperature, lube oil temperature, and turning gear operation are specified by the engine manufacturer and reproduced in the vessel's operating procedures. Spare parts lists, inspection reports, and bunker notes do not contain operating instructions. Following the approved procedure prevents thermal shock and starting difficulties.

Question 9Marine engine operation and watchkeeping

During manoeuvring, the bridge orders repeated engine movements. What is the duty engineer's correct practice regarding the starting air compressor?

  1. Switch the compressor to manual and leave it unattended
  2. Run the compressor to keep receiver pressure topped up and monitor the number of starts used Correct answer.
  3. Stop the compressor to reduce noise in the engine room
  4. Drain the receiver completely between each start

Explanation

Manoeuvring consumes starting air rapidly, so the compressor must run to maintain receiver pressure above the minimum, and the engineer should track the starts used against the reserve. Stopping the compressor or draining the receiver reduces the available reserve. Leaving machinery unattended during manoeuvring is not acceptable.

Question 10Marine engine operation and watchkeeping

The main engine crankcase oil mist detector alarms during normal sea passage. What should the duty engineer do first?

  1. Increase crankcase ventilation to dilute the mist
  2. Acknowledge the alarm and reset it to clear the indication
  3. Open the crankcase doors immediately to inspect the bearings
  4. Reduce engine load and investigate the alarm indication and crankcase condition before considering a stop Correct answer.

Explanation

An oil mist alarm is a serious indication of a possible hot spot, so load should be reduced to limit heat generation while the alarm and crankcase condition are investigated. The engine is stopped if the condition persists or worsens. Opening crankcase doors while the engine is hot risks an inrush of air and explosion, and simply resetting the alarm conceals the hazard.

Question 11Marine engine operation and watchkeeping

The fuel oil purifier begins discharging dirty oil with the water seal repeatedly breaking. Which cause is most likely?

  1. The fuel oil viscosity is too low for the purifier
  2. The sludge discharge interval is too long
  3. The bowl is incorrectly assembled or the operating water supply is faulty Correct answer.
  4. The purifier motor is running above synchronous speed

Explanation

A repeatedly breaking water seal usually points to incorrect bowl assembly, worn seals, or a faulty operating water supply that fails to seat the bowl correctly. Low viscosity, motor overspeed, and long sludge intervals do not cause the seal itself to fail. The purifier should be stopped, inspected, and correctly reassembled before restart.

Question 12Marine engine operation and watchkeeping

Auxiliary boiler water level is showing low on the gauge glass while the feed pump is running. What is the correct first action?

  1. Open the boiler blowdown valve to lower the level further
  2. Trip the boiler immediately without further checks
  3. Add water at maximum rate to restore the level quickly
  4. Check the gauge glass and feed system for a false indication before adding water rapidly Correct answer.

Explanation

A low level indication with the feed pump running may be a false reading from a blocked gauge glass or a feed control fault, so the indication must be verified before action. Rapid uncontrolled filling of a boiler with an uncertain level risks overfilling and carry-over. Blowing down would worsen a genuine low level.

Question 13Marine engine operation and watchkeeping

Which reading best indicates that the main engine turbocharger is suffering from exhaust gas leakage past the turbine nozzle ring?

  1. A rise in turbocharger speed with a fall in scavenge air pressure Correct answer.
  2. A fall in exhaust gas temperature at constant load
  3. A steady turbocharger speed with unchanged scavenge pressure
  4. A fall in turbocharger speed with a rise in scavenge air pressure

Explanation

Exhaust gas bypassing the nozzle ring reduces the energy transferred to the turbine, so turbocharger speed and scavenge air pressure fall together with a rise in exhaust temperature. The combination of rising speed with falling scavenge pressure is not consistent with gas leakage. Steady readings and lower exhaust temperature do not indicate this fault.

Question 14Marine engine operation and watchkeeping

During an unmanned engine room period the fire detection system alarms for the engine room. What is the correct sequence of actions for the engineer on call?

  1. Silence the alarm remotely and continue the watch until the next round
  2. Open the engine room skylights to ventilate smoke before entry
  3. Proceed to the engine room, investigate the alarm source, and prepare to stop machinery and fight the fire Correct answer.
  4. Start the emergency fire pump before confirming a fire exists

Explanation

The engineer on call must attend, identify the source of the alarm, and be ready to shut down machinery and use the fixed firefighting arrangements. Silencing the alarm without investigation leaves the hazard unaddressed. Starting the emergency pump or opening skylights before confirming a fire can worsen conditions by adding air to a fire.

Question 15Marine engine operation and watchkeeping

The main engine is running and the jacket cooling water expansion tank level is falling steadily with no visible external leak. Which internal cause should be investigated?

  1. A blocked jacket water cooler on the seawater side
  2. Normal evaporation from the expansion tank
  3. A leaking cylinder liner or cylinder head sealing ring allowing water into the combustion space Correct answer.
  4. A faulty expansion tank level gauge only

Explanation

A steady loss of jacket water with no external leak suggests an internal leak, commonly a cracked liner, faulty sealing ring, or cylinder head leak passing water into the combustion space or scavenge air. Gauge faults and normal evaporation would not produce a continuous fall. A blocked cooler would affect temperatures rather than consume water.

Question 16Marine engine operation and watchkeeping

What is the correct action when the main engine lube oil pressure falls below the alarm setpoint during sea passage?

  1. Reset the alarm and continue at the same load
  2. Reduce load, verify the pressure reading, and be prepared to stop the engine if pressure does not recover Correct answer.
  3. Increase load to raise the lube oil pump speed
  4. Close the lube oil cooler bypass to raise pressure

Explanation

Low lube oil pressure threatens bearing integrity, so load is reduced to lower heat generation while the reading is verified and the cause investigated. If pressure does not recover the engine must be stopped. Increasing load worsens the condition, and closing the cooler bypass affects temperature rather than pressure.

Question 17Marine engine operation and watchkeeping

A duty engineer is asked to take over a watch that has just started. Which condition must be confirmed before accepting the watch?

  1. That the previous engineer has completed all planned maintenance
  2. That all machinery is in a safe and satisfactory condition and the previous watch is fit to hand over Correct answer.
  3. That the logbook has been signed by the master
  4. That the chief engineer is present in the engine room

Explanation

The relieving engineer should not accept the watch if there is reason to believe the outgoing engineer is unfit or the machinery condition is unsatisfactory. Planned maintenance completion, the chief engineer's presence, and master's signature are not conditions for accepting a routine watch. Accepting an unsafe handover transfers responsibility without adequate information.

Question 18Marine engine operation and watchkeeping

The auxiliary engine driving the emergency generator is tested weekly. Which check confirms the generator will start automatically on loss of main power?

  1. Confirm the fuel tank is full and the engine is warm
  2. Run the engine on load manually for ten minutes
  3. Check the battery voltage with the engine stopped only
  4. Simulate a main power failure and confirm automatic start and breaker closure Correct answer.

Explanation

The automatic start function is only proven by simulating a main power failure and observing the engine start and the breaker close onto the emergency switchboard. Manual running, battery voltage checks, and fuel level checks are useful but do not test the automatic sequence. The test should be recorded in the logbook.

Question 19Marine engine operation and watchkeeping

Which practice best protects the main engine during a long period of slow steaming in cold weather?

  1. Maintain jacket water and lube oil temperatures within the manufacturer's range and monitor for low-load deposits Correct answer.
  2. Reduce jacket water temperature to match the lower load
  3. Stop the cylinder lubricators to save oil at low load
  4. Run the engine below the minimum continuous rating without any adjustment

Explanation

Slow steaming in cold conditions requires maintaining correct jacket water and lube oil temperatures and watching for low-load fouling and deposits. Reducing jacket temperature or stopping cylinder lubrication causes corrosion and wear. Running below the minimum continuous rating without adjustment risks poor combustion and turbocharger fouling.

Question 20Marine engine operation and watchkeeping

The main engine is fitted with a scavenge space fire detection and extinguishing system. What is the correct response to a scavenge space fire alarm while the engine is running?

  1. Open the scavenge space doors to inspect the fire directly
  2. Continue running and monitor the alarm until the next port
  3. Increase engine speed to blow the fire out through the exhaust
  4. Reduce engine speed, stop the engine if the alarm persists, and activate the fixed extinguishing system as per procedure Correct answer.

Explanation

A scavenge space fire is fought by reducing speed and stopping the engine to remove the air supply, then activating the fixed extinguishing system in accordance with the vessel procedure. Increasing speed feeds the fire, and opening the doors admits air and endangers personnel. Continuing to run allows the fire to spread.

Question 21Marine engine operation and watchkeeping

A fuel oil separator is being run on heavy fuel oil. Which adjustment is required as the fuel viscosity increases?

  1. Increase the throughput to shorten the residence time
  2. Raise the fuel temperature to the correct separation viscosity and adjust the throughput accordingly Correct answer.
  3. Reduce the fuel temperature to increase separation density difference
  4. Reduce the bowl speed to improve separation

Explanation

Heavy fuel oil must be heated to the viscosity that gives efficient separation, and the throughput set so residence time is adequate. Lowering temperature or increasing throughput reduces separation efficiency. Bowl speed is fixed by the drive and should not be reduced.

Question 22Marine engine operation and watchkeeping

During a blackout, the emergency generator has started and is supplying the emergency switchboard. What should the duty engineer check first?

  1. That the main switchboard is re-energised before any other action
  2. That all accommodation air conditioning is restored
  3. That essential services such as steering gear, emergency lighting, and navigation equipment are supplied Correct answer.
  4. That the main engine can be restarted immediately at full load

Explanation

After a blackout the priority is to confirm the emergency switchboard is supplying essential services including steering gear, emergency lighting, and navigation equipment. Restoring the main switchboard and non-essential loads comes after essential services are confirmed. Restarting the main engine at full load is not the first priority.

Question 23Marine engine operation and watchkeeping

The main engine exhaust gas boiler is producing insufficient steam at normal engine load. Which combination of causes should be investigated first?

  1. A low fuel oil viscosity and a high injector cooling water temperature
  2. A high turbocharger speed and a low scavenge air temperature
  3. Water-side fouling, gas-side soot deposits, and a faulty steam pressure control valve Correct answer.
  4. A high feed water temperature and a full water level

Explanation

Reduced steam output at normal load usually results from poor heat transfer due to water-side scaling or gas-side soot, or from a control valve passing or stuck. Feed water temperature and level affect control but not heat transfer to the same degree. Fuel viscosity and turbocharger readings do not directly explain low steam generation.

Question 24Marine engine operation and watchkeeping

A main engine indicator diagram shows a reduced maximum combustion pressure with a normal compression pressure. Which fault is most consistent with these readings?

  1. A leaking exhaust valve
  2. A faulty fuel injector or fuel pump delivering less fuel than required Correct answer.
  3. A partially choked scavenge air cooler
  4. Excessive cylinder liner wear

Explanation

Normal compression pressure with reduced maximum combustion pressure points to a fuel delivery fault such as a worn injector or pump, since compression is unaffected. Excessive liner wear and a leaking exhaust valve would lower compression pressure. A choked air cooler would affect scavenge air and compression rather than isolating the firing pressure.

Question 25Marine engine operation and watchkeeping

During a long ocean passage the main engine crankcase pressure is rising slowly and the crankcase mist detector shows a gradual upward trend. What is the most appropriate response?

  1. Reduce cylinder oil feed to lower mist generation
  2. Ignore the trend until the mist detector alarms at its setpoint
  3. Investigate for a hot spot or blow-by while monitoring trends, and prepare to stop the engine if the trend continues Correct answer.
  4. Open the crankcase ventilation fully and continue at full load

Explanation

A gradual rise in crankcase pressure with an upward mist trend suggests developing blow-by or a hot spot, and early investigation allows the fault to be found before an alarm or explosion risk develops. Waiting for the alarm removes the early warning margin. Opening ventilation or reducing cylinder oil does not address the cause.

Question 26Marine engine operation and watchkeeping

Under a UMS (unattended machinery space) classification, which alarm is arranged to give the earliest warning to the duty engineer before a critical shutdown occurs?

  1. The slow-down alarm on the main engine safety system Correct answer.
  2. The crankcase oil mist detector high alarm
  3. The main engine overspeed trip alarm
  4. The emergency generator start-failure alarm

Explanation

In a UMS engine room the alarm and safety systems are arranged in tiers: a slow-down (or pre-warning) alarm operates first so the engineer has time to attend before a full shut-down is initiated. The slow-down stage is deliberately set before the shut-down stage so that propulsion is not lost without warning. Shut-down alarms and trips indicate the later stage of the fault.

Question 27Marine engine operation and watchkeeping

Which parameter is normally logged for the main engine at each watch and compared against the previous reading to detect a developing fault?

  1. Colour of the crankcase oil on the dipstick
  2. Number of starts recorded on the counter
  3. Sound level in the engine room
  4. Exhaust gas temperature at each cylinder outlet Correct answer.

Explanation

Exhaust gas temperature at each cylinder outlet is a key condition-monitoring reading: a rising or deviating value points to injector, exhaust valve or scavenge problems on that unit. Watch logs record such readings so trends can be compared between watches. The other items are not routine condition indicators for detecting developing faults.

Question 28Marine engine operation and watchkeeping

When the bridge telegraph orders 'Dead Slow Ahead' during manoeuvring, what must the duty engineer confirm before acknowledging?

  1. That the turning gear is still engaged
  2. That the telegraph order has been logged in the oil record book
  3. That the engine has actually responded and is running in the ordered direction Correct answer.
  4. That the fuel oil booster pump has been stopped

Explanation

The engineer must acknowledge an order only after the engine has responded correctly, because the bridge relies on that acknowledgement to know the propeller is doing what was ordered. Confirming direction and response prevents a wrong-direction movement during manoeuvring. The other listed actions are either unsafe or irrelevant to acknowledging the order.

Question 29Marine engine operation and watchkeeping

What is the correct action if the main engine fails to start on air when the bridge orders ahead during manoeuvring?

  1. Increase starting air pressure above the design limit to force a start
  2. Inform the bridge immediately that the engine has not started and investigate the cause Correct answer.
  3. Open the indicator cocks and continue cranking on air
  4. Keep the starting air handle in the start position until the engine fires

Explanation

The bridge must be told at once so it can adjust the manoeuvre and avoid a collision or grounding situation. Continued cranking wastes starting air and can damage the air system or starter. The cause, such as low air pressure, a stuck valve or a fuel problem, is then investigated methodically.

Question 30Marine engine operation and watchkeeping

Which action is required before a duty engineer leaves the engine room during a manned watch?

  1. Stop the main engine lube oil pump
  2. Close the starting air supply to the main engine
  3. Ensure the watch is covered or the bridge is informed and alarms are transferred as required Correct answer.
  4. Switch off all engine room ventilation fans

Explanation

A watchkeeper must never leave the machinery space unmanned without ensuring cover and informing the bridge, because the safety of the ship depends on continuous supervision. Where the ship is not classed for unattended operation, alarms must be transferred to the bridge before leaving. The other actions would disrupt essential services.

Question 31Marine engine operation and watchkeeping

What is the main purpose of the engine room dead-man alarm (watchkeeper alarm) during UMS operation?

  1. To raise an alarm if the duty engineer does not reset it within the set period Correct answer.
  2. To monitor the main engine speed
  3. To record the number of personnel entering the space
  4. To detect fire in the engine room

Explanation

The dead-man alarm requires the duty engineer to reset it at set intervals during rounds, proving that the watchkeeper is active and conscious. If it is not reset within the time, an alarm is raised in the accommodation and on the bridge. It is a personnel-safety device, not a fire or speed monitor.

Question 32Marine engine operation and watchkeeping

During a watch, the main engine fuel oil viscosity controller shows the fuel viscosity falling below the setpoint while the fuel temperature is unchanged. Which action should the duty engineer take first?

  1. Increase the fuel temperature setpoint immediately
  2. Switch to diesel oil without informing the bridge
  3. Check the viscosity sensor and controller for a fault and verify with a manual reading Correct answer.
  4. Reduce the engine load to lower fuel consumption

Explanation

A falling viscosity reading with unchanged temperature suggests a sensor or controller fault rather than a real fuel change. The reading should be verified manually before any adjustment, because adjusting temperature to chase a faulty signal can push the real viscosity outside limits. Load changes and fuel switching are not the first response.

Question 33Marine engine operation and watchkeeping

What does a rising main engine jacket cooling water temperature with a steady sea water outlet temperature most likely indicate?

  1. A faulty sea water pump
  2. Low sea water temperature
  3. Reduced fresh water flow through the engine or a fouled fresh water cooler on the water side Correct answer.
  4. A blocked sea water inlet strainer

Explanation

If the sea water outlet is steady, the sea water side is working normally, so the problem lies on the fresh water side, such as reduced flow or a fouled cooler. A restricted fresh water circuit cannot remove heat from the engine, so the jacket water temperature rises. Sea water side faults would normally show in the sea water outlet temperature.

Question 34Marine engine operation and watchkeeping

The main engine is running at full load and the turbocharger is surging repeatedly. Which immediate action is most appropriate?

  1. Open the turbocharger washing water valve while at full load
  2. Increase load to blow the turbocharger clear
  3. Stop the main engine immediately without informing the bridge
  4. Reduce engine load and investigate for fouled turbine or nozzle ring and air-side restriction Correct answer.

Explanation

Surging indicates the compressor is stalling, commonly from a fouled turbine, nozzle ring or air cooler, or from an air-side restriction. Reducing load lowers the pressure ratio and stops the surging while the cause is investigated. Increasing load or washing at full load would worsen the condition.

Question 35Marine engine operation and watchkeeping

During a watch, the main engine fuel oil supply pressure drops slowly but the fuel oil booster pump discharge pressure remains normal. Which cause is most likely?

  1. A partially blocked fuel oil filter on the engine supply line Correct answer.
  2. A failed booster pump
  3. An air lock in the booster pump suction
  4. A closed fuel oil service tank valve

Explanation

If the booster pump discharge is normal but the pressure at the engine falls, the restriction must be downstream of the pump, such as a partially blocked filter. A pump or suction fault would also lower the pump discharge pressure. A closed tank valve would affect the pump suction and discharge readings together.

Question 36Marine engine operation and watchkeeping

What is the correct response when the main engine governor actuator alarm activates during sea passage?

  1. Immediately trip the main engine
  2. Increase the governor setpoint to compensate
  3. Ignore the alarm as the governor is duplicated
  4. Inform the bridge, monitor engine speed and be prepared to control the engine manually Correct answer.

Explanation

A governor fault threatens automatic speed control, so the bridge must be informed and the engineer must monitor speed closely in case manual control is needed. The engine is not tripped immediately unless the speed becomes unsafe. Raising the setpoint does not correct an actuator fault.

Question 37Marine engine operation and watchkeeping

The main engine is running and the scavenge air receiver pressure is low while the turbocharger speed is normal. Which cause is most likely?

  1. Leakage from the scavenge air receiver or a leaking air cooler Correct answer.
  2. A fouled turbocharger turbine
  3. A blocked exhaust gas boiler
  4. A worn fuel injection pump

Explanation

With turbocharger speed normal, the compressor is delivering air, so low receiver pressure points to leakage downstream, such as a leaking receiver or air cooler. A fouled turbine would reduce turbocharger speed. Fuel injection and exhaust boiler faults do not directly lower scavenge pressure in this way.

Question 38Marine engine operation and watchkeeping

During manoeuvring, the main engine is required to run astern. Which precaution must the duty engineer observe?

  1. Open the indicator cocks during the astern movement
  2. Ensure the engine has slowed sufficiently before reversing and monitor starting air consumption Correct answer.
  3. Increase the fuel index to maximum immediately
  4. Disengage the turning gear after the engine has started

Explanation

Reversing at high speed imposes large loads on the running gear and consumes large amounts of starting air, so the engine must be allowed to slow before the astern start. Starting air consumption is monitored so that enough remains for further movements. The other actions would cause damage or are impossible during running.

Question 39Marine engine operation and watchkeeping

What is the purpose of the main engine safety system slow-down function during a critical parameter deviation?

  1. To transfer control to the local manoeuvring stand
  2. To stop the engine instantly to protect the machinery
  3. To reduce engine power automatically so the fault can be attended before a full shut-down Correct answer.
  4. To alarm only on the bridge without changing engine power

Explanation

The slow-down function reduces power automatically when a parameter exceeds its limit, giving the engineer time to correct the fault while preserving propulsion. It is deliberately less drastic than a shut-down. It does not simply alarm or transfer control.

Question 40Marine engine operation and watchkeeping

The main engine crankcase oil level is found to be rising slowly during a sea passage. Which cause should the duty engineer investigate first?

  1. Water or fuel leaking into the crankcase from a defective cooler or injection component Correct answer.
  2. Overfilling during the last oil change
  3. Normal oil expansion due to engine warming
  4. A faulty level gauge only

Explanation

A rising crankcase level in service usually means a foreign fluid is entering, such as cooling water from a leaking cooler or fuel from a defective injection component. This dilutes the oil and threatens bearing lubrication, so it must be investigated promptly. Normal thermal expansion is small and stabilises once at operating temperature.

Question 41Marine engine operation and watchkeeping

What is the correct action when the main engine cylinder exhaust gas temperature deviates significantly on one unit while the others remain normal?

  1. Open the starting air valve to that cylinder
  2. Increase the fuel index to bring the temperature back into line
  3. Reduce load if necessary and investigate that unit's injector, exhaust valve and scavenge conditions Correct answer.
  4. Adjust the governor droop setting

Explanation

A single-cylinder deviation points to a fault local to that unit, such as a faulty injector, a leaking exhaust valve or poor scavenging. The engineer should investigate that unit and reduce load if the deviation is severe. Adjusting fuel index or governor settings does not correct a mechanical fault and may worsen it.

Question 42Marine engine operation and watchkeeping

During a blackout recovery, the main engine is restarted after the emergency generator has taken the emergency switchboard. Which check is essential before restarting the main engine?

  1. Confirm that the steering gear is on the emergency supply
  2. Confirm that the main lube oil and cooling water pumps are running and pressures are normal Correct answer.
  3. Confirm that the emergency generator is fully loaded
  4. Confirm that the bridge has logged the blackout

Explanation

After a blackout the main engine must not be restarted until the auxiliary systems that support it, particularly lube oil and cooling water, are running at normal pressure. Starting without lubrication or cooling can destroy bearings and liners. The other checks are useful but do not protect the engine directly.

Question 43Marine engine operation and watchkeeping

The main engine runs at steady load. Exhaust-gas boiler steam pressure is falling while feed water and steam demand are unchanged, and the steam dump valve is confirmed closed. Which listed cause should be investigated?

  1. Soot fouling on the exhaust gas boiler heating surfaces Correct answer.
  2. An open steam dump valve to the atmosphere
  3. A rising engine load
  4. A failed feed water pump

Explanation

With the stated steam demand, feed supply, and engine load unchanged, soot fouling is the listed condition that can reduce heat transfer and steam production. The stem explicitly rules out an open dump valve.

Question 44Marine engine operation and watchkeeping

Which practice best protects the main engine when it is expected to run for a long period at very low load?

  1. Close the scavenge air drain valves permanently
  2. Follow the manufacturer's low-load operating instructions, including any minimum load limits and periodic load increases Correct answer.
  3. Reduce cylinder oil feed to minimum
  4. Run the engine at full load for a short period every watch

Explanation

Long low-load operation can cause poor combustion, fouling and turbocharger problems, so the manufacturer's low-load guidance must be followed, including minimum load limits and periodic load increases. Reducing cylinder oil or closing drains would worsen fouling. Brief full-load running is not the specified remedy.

Question 45Marine engine operation and watchkeeping

During a watch, the main engine tachometer reading fluctuates while the fuel index remains steady. Which cause is most likely?

  1. Low starting air pressure
  2. A fouled turbocharger
  3. A faulty tachometer sensor or loose connection Correct answer.
  4. A blocked fuel oil filter

Explanation

If the fuel index is steady but the indicated speed fluctuates, the fault is most likely in the speed sensing circuit rather than the engine itself. A loose connection or faulty sensor produces erratic readings. Fuel, turbocharger and starting air faults would normally show in the fuel index or other parameters.

Question 46Marine engine operation and watchkeeping

The main engine is fitted with a cylinder lubricator and the alarm indicates low lubricator flow to one cylinder. What is the correct response?

  1. Switch off the alarm and continue the voyage
  2. Investigate the lubricator pump and line for that cylinder and reduce load if necessary Correct answer.
  3. Increase the engine load to clear the line
  4. Ignore the alarm as cylinder oil is not critical

Explanation

Cylinder lubricating oil is essential to liner and piston ring life, and a low-flow alarm on one cylinder must be investigated promptly. If the fault cannot be corrected quickly, load should be reduced to protect that unit. Ignoring or disabling the alarm risks severe liner wear and scavenge space problems.

Question 47Marine engine operation and watchkeeping

During a sea passage, the main engine crankcase mist detector gives a high alarm and the crankcase pressure is rising. What is the correct sequence of actions?

  1. Continue running and check the alarm at the next watch
  2. Increase load to burn off the vapour
  3. Reduce load, inform the bridge, prepare to stop the engine and investigate the affected unit Correct answer.
  4. Open the crankcase doors immediately to inspect

Explanation

A high oil mist alarm with rising crankcase pressure suggests overheating of a bearing or piston, which can lead to a crankcase explosion. Load should be reduced and the bridge informed so the engine can be stopped in a controlled way, then the affected unit investigated. Opening crankcase doors while hot admits air and risks an explosion.

Question 48Marine engine operation and watchkeeping

An indicator diagram from one main engine cylinder shows a normal compression pressure but a reduced maximum combustion pressure. Which fault is most likely?

  1. A leaking piston ring
  2. A faulty fuel injection pump delivering insufficient fuel to that cylinder Correct answer.
  3. A worn turbocharger bearing
  4. A blocked scavenge air port

Explanation

Normal compression pressure shows that the cylinder is sealing and scavenging correctly, so the shortfall is in combustion. A reduced maximum combustion pressure with normal compression points to insufficient fuel delivery, such as a faulty injection pump. Ring, scavenge port and turbocharger faults would also lower the compression pressure.

Question 49Marine engine operation and watchkeeping

The main engine fuel oil separator is being run on heavy fuel oil and the sludge discharge is frequent with a high water content in the separated oil. Which action is most appropriate?

  1. Reduce the bowl temperature to thicken the oil
  2. Stop the separator and rely on settling tanks
  3. Increase the throughput to reduce residence time
  4. Reduce the throughput and adjust the bowl temperature to the correct separation viscosity Correct answer.

Explanation

Frequent sludge discharge and water carry-over indicate the separator is overloaded or the oil is too viscous for efficient separation. Reducing throughput increases residence time and adjusting the bowl temperature to the correct viscosity improves separation. Increasing throughput or lowering temperature worsens the problem.

Question 50Marine engine operation and watchkeeping

During a long ocean passage, the main engine scavenge space fire detection system activates. What is the correct initial response?

  1. Reduce engine load, inform the bridge and prepare to stop the engine and apply the fixed extinguishing system as instructed Correct answer.
  2. Increase load to blow out the fire
  3. Continue running and monitor the alarm
  4. Open the scavenge space doors to inspect visually

Explanation

A scavenge space fire is a serious emergency: load must be reduced, the bridge informed and the engine prepared for stopping, with the fixed extinguishing system applied according to the procedure. Opening scavenge doors admits air and can cause a violent flare-up. Increasing load feeds the fire with more air and fuel.