STCW Marine Engineering 4 — Questions and Answers
Question 1: What is the STCW requirement for a Chief Engineer officer on a ship of 3,000 kW or more propulsion power?
- STCW Certificate III/2 — Chief Engineer (Correct answer)
- STCW Certificate III/3 — Chief Engineer on ships of less than 3,000 kW
- STCW Certificate III/6
- No specific STCW certificate required above 3,000 kW
Correct answer: STCW Certificate III/2 — Chief Engineer
STCW Regulation III/2 and Table A-III/2 specify the competence requirements for Chief Engineers on ships with 3,000 kW propulsion power or more.
Question 2: What does the term 'viscosity index' indicate about a lubricating oil?
- Its resistance to oxidation
- How much its viscosity changes with temperature (Correct answer)
- Its detergent capacity
- Its flash point temperature
Correct answer: How much its viscosity changes with temperature
A high viscosity index means the oil's viscosity changes relatively little between hot and cold temperatures, which is desirable for consistent lubrication.
Question 3: What is the primary purpose of the alpha-lubrication (pulse lubrication) system on a large slow-speed two-stroke engine?
- To lubricate main bearings continuously
- To deliver cylinder oil precisely timed with piston movement to reduce consumption and reduce deposits (Correct answer)
- To circulate system oil through the crosshead bearings
- To pre-lubricate the engine before starting
Correct answer: To deliver cylinder oil precisely timed with piston movement to reduce consumption and reduce deposits
Electronically controlled pulse lubrication injects cylinder oil at the optimal moment in the stroke, reducing oil consumption and carbon deposits compared to constant-rate drip systems.
Question 4: Which of the following best describes the function of a freshwater generator (evaporator) aboard ship?
- Converts bilge water into potable water using UV treatment
- Uses waste heat from jacket water to evaporate seawater and produce freshwater by condensation (Correct answer)
- Produces fresh water from seawater using high-pressure reverse osmosis only
- Recirculates and purifies tank water using chemical dosing
Correct answer: Uses waste heat from jacket water to evaporate seawater and produce freshwater by condensation
Most shipboard freshwater generators use engine jacket water heat under vacuum to evaporate seawater at low temperature, then condense the vapor to produce fresh water.
Question 5: What is the significance of the Total Base Number (TBN) of a cylinder lubricating oil?
- It indicates oil viscosity at 100°C
- It measures the oil's ability to neutralize acidic combustion products (Correct answer)
- It shows the detergent additive concentration by volume
- It specifies the oil's minimum flash point
Correct answer: It measures the oil's ability to neutralize acidic combustion products
TBN represents the alkaline reserve in the oil that neutralizes sulfuric and other acids formed during combustion, protecting cylinder liner surfaces from corrosion.
Question 6: When operating a purifier (centrifugal separator) for fuel oil, what is the effect of an incorrect gravity disc (dam ring)?
- The purifier will overheat the fuel
- Water will not be separated properly, or fuel will be discharged with the water sludge (Correct answer)
- The fuel flow rate will double automatically
- The purifier bowl will fail to self-clean
Correct answer: Water will not be separated properly, or fuel will be discharged with the water sludge
The gravity disc controls the oil-water interface position; a disc of incorrect size causes the interface to shift so fuel exits with sludge or water remains in the fuel.
Question 7: Under STCW, what is the minimum rest period requirement for engineers in a watch system during a voyage?
- 6 hours in any 24-hour period
- 10 hours in any 24-hour period and 77 hours in any 7-day period (Correct answer)
- 8 hours per day without exception
- 12 hours in any 24-hour period
Correct answer: 10 hours in any 24-hour period and 77 hours in any 7-day period
STCW requires a minimum of 10 hours of rest in any 24-hour period, with no more than two periods of rest (one at least 6 hours), and 77 hours rest in any 7-day period.
STCW Marine Engineering 4
What is the STCW requirement for a Chief Engineer officer on a ship of 3,000 kW or more propulsion power?