Examination Practice Questions And

Coast Guard QMED Junior Engineer Examination Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a bilge pump on a ship?
• To circulate coolant in the engine
• To pump fuel to the engine
• To remove water from the bilge
• To inflate life rafts

Rationale: Bilge pumps are designed to remove unwanted water from the

bilge to prevent flooding and maintain vessel stability.

• What is the normal operating temperature for a diesel engine jacket

water system?

A. 100–120°F 1 / 4

B. 160–200°F

C. 220–250°F

D. 300–350°F

Rationale: Diesel engines typically operate within 160–200°F for efficient

cooling without causing thermal stress.

• Which type of valve is used to prevent backflow in piping systems?
• Globe valve
• Check valve
• Gate valve
• Needle valve

Rationale: Check valves allow fluid to flow in one direction and prevent

reverse flow, protecting pumps and piping.

• What is the primary function of a condenser in a steam propulsion

system?

• Heat the feedwater
• Convert exhaust steam back into water
• Increase steam pressure
• Filter impurities from fuel

Rationale: Condensers turn exhaust steam into water for reuse in the

boiler, improving efficiency and conserving water.

• Which of the following is considered a flammable liquid on a vessel?
• Water
• Lubricating oil 2 / 4

• Gasoline
• Antifreeze

Rationale: Gasoline has a low flash point and high vapor pressure, making

it highly flammable.

6. The purpose of a ship’s evaporator is to:

• Heat fuel oil
• Produce steam for propulsion
• Produce fresh water from seawater
• Cool the main engine

Rationale: Evaporators distill seawater to produce potable water for crew

use and machinery cooling.

• Which instrument measures the pressure in a boiler?
• Thermometer
• Flow meter
• Pressure gauge
• Tachometer

Rationale: Pressure gauges indicate boiler pressure to ensure safe

operation within design limits.

• What is the main advantage of using a centrifugal pump over a

reciprocating pump?

• Higher discharge pressure
• Simpler to repair
• Smooth, continuous flow 3 / 4

• Lower speed operation

Rationale: Centrifugal pumps provide continuous, steady flow suitable for

most shipboard applications.

• A marine diesel engine is overspeeding. The most immediate action

should be to:

• Increase fuel supply
• Reduce fuel or stop the engine
• Close the cooling water valve
• Open the bilge pump

Rationale: Reducing or stopping fuel supply prevents engine damage and

unsafe operating conditions.

• Which of the following is a sign of lubrication oil starvation in a

bearing?

• Normal operating temperature
• Clean oil film
• Overheating and scoring
• Low vibration

Rationale: Insufficient lubrication leads to metal-to-metal contact, causing

overheating, wear, and scoring.

• What is the main function of a turbocharger on a diesel engine?
• Reduce engine noise
• Increase air intake for better combustion
• Filter exhaust gases
• / 4