National Maritime Center

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1 National Maritime Center Providing Credentials to Mariners U.S.C.G. Merchant Marine Exam (Sample Examination) Page 1 of 26

2 U.S.C.G. Merchant Marine Exam Illustrations: 12 Choose the best answer to the following Multiple Choice Questions. 1. In a closed-loop process control system featuring negative feedback, what is the function of the error detector within the controller? o (A) The error detector computes the sum of the measured value of the controlled variable and the desired value (set point). o (B) The error detector computes the quotient of the measured value of the controlled variable and the desired value (set point). (C) The error detector computes the difference between the measured value of the controlled variable and the desired value (set point). o (D) The error detector computes the product of the measured value of the controlled variable and the desired value (set point). If choice C is selected set score to Which of the wave shapes shown in the illustration is termed a sinusoidal wave? Illustration EL-0088 (A) A o (B) B o (C) C o (D) D 3. Which of the following fixed temperature heat-actuated fire detectors is the most prone to false alarms? o (A) fusible metal detector o (B) liquid expansion detector o (C) snap-action bimetallic disc (D) bimetallic strip detector If choice D is selected set score to What statement is true concerning the electrical diagram shown in figure "B" of the illustration? Illustration EL-0019 o (A) The voltages measured across "R 1 ", "R 2 " and "R 3 " will be different if "R 1 ", "R 2 " and "R 3 " have different values. o (B) The total resistance equals R 1 + R 2 + R 3. (C) "R 1 ", "R 2 ", and "R 3 " are connected in parallel. o (D) "R 1 ", "R 2 ", and "R 3 " are connected in series. If choice C is selected set score to 1. Page 2 of 26

3 U.S.C.G. Merchant Marine Exam Illustrations: A precharged bladder-type accumulator used in a hydraulic system, can be potentially dangerous if. o (A) the bladder contacts the top of the poppet o (B) the inert gas is exposed to hydraulic oil o (C) it is precharged with dry nitrogen (D) the charging valve stem breaks while at normal working pressure If choice D is selected set score to Three 12 volt, lead-acid, batteries connected in series will develop how many volts? o (A) 12 volts o (B) 24 volts (C) 36 volts o (D) 48 volts If choice C is selected set score to If an air compressor is fitted with a hand-off-auto (H-O-A) control station, what statement concerning operation is true? (A) In the hand mode, the compressor will run continuously with unloading. o (B) In the hand mode, the compressor will cycle on and off. o (C) In the auto mode, the compressor will run continuously with unloading. o (D) In the off mode, the compressor will cycle on and off. 8. Which of the following statements is true concerning the gauge labeled "A" of the illustrated gauge manifold set? Illustration GS-RA-01 (A) The gauge labeled "A" is a compound gauge and is usually color-coded blue. o (B) The gauge labeled "A" is a compound gauge and is usually color-coded red. o (C) The gauge labeled "A" is a standard pressure gauge and is usually color-coded blue. o (D) The gauge labeled "A" is a standard pressure gauge and is usually color-coded red. Page 3 of 26

4 U.S.C.G. Merchant Marine Exam Illustrations: What statement is true concerning the construction of watertight bulkheads? (A) The strakes of the bulkhead are horizontal and the stiffeners are vertical and the bulkhead must have increasingly greater strength towards the base. o (B) The strakes of the bulkhead are horizontal and the stiffeners are vertical and the bulkhead must have increasingly greater strength towards the top. o (C) The strakes of the bulkhead are vertical and the stiffeners are horizontal and the bulkhead must have increasingly greater strength towards the top. o (D) The strakes of the bulkhead are vertical and the stiffeners are horizontal and the bulkhead must have increasingly greater strength towards the base. 10. Both the direction of flow and fluid flow rate of a variable displacement radial piston pump are determined by the relative positions of the. o (A) pump shaft and central valve (B) floating ring and cylinder body o (C) floating ring and pump shaft o (D) pump shaft and horizontal ports 11. When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell? (A) comparing the specific gravity of the electrolyte in each cell o (B) taking an open circuit voltage test of individual cells o (C) taking each cell's temperature with a calibrated mercury thermometer o (D) visually inspecting the electrolyte levels of each cell 12. In a two-stage centrifugal air conditioning system, the liquid refrigerant passes through the condenser directly to what component? o (A) expansion valve (B) economizer o (C) chiller o (D) evaporator Page 4 of 26

5 U.S.C.G. Merchant Marine Exam Illustrations: When a refrigeration compressor is in the "off" cycle, the thermal expansion valve will react in what way? (A) it will continue to function as a result of the net balance of forces acting on the diaphragm o (B) it will always remain in the same position just prior to the cycling off of the compressor o (C) it will always completely close regardless of whether or not the system employs a pump down cycle o (D) it will always open wide regardless of whether or not the system employs a pump down cycle 14. As shown in the illustrated diagnostic setup for locating a shorted field coil of a ten-pole synchronous motor, if 240 VAC/60 Hz is applied across the brushes, what would be the individual voltage drops measured across each field coil assuming that none of the field coils are shorted? Illustration EL o (A) 6 VAC o (B) 12 VAC (C) 24 VAC o (D) 48 VAC If choice C is selected set score to On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase? o (A) the valve will further close, lowering evaporator pressure and raising suction pressure (B) the valve will further close, raising evaporator pressure and lowering suction pressure o (C) the valve will further open, lowering evaporator pressure and raising suction pressure o (D) the valve will further open, raising evaporator pressure and lowering suction pressure 16. Alkyl benzene ISO 32 cst synthetic refrigerant oil is miscible and suitable to use with which of the following refrigerants? (A) R-22 o (B) R-32 o (C) R-134a o (D) R-143a Page 5 of 26

6 U.S.C.G. Merchant Marine Exam Illustrations: The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means? o (A) tack welding on the sides (B) heavy coil springs o (C) discharge pressure in the relief valve return line o (D) large Teflon gaskets 18. Which of the listed pressure-control valves would be used in a hydraulic system to temporarily divert some, or all of the pump discharge until the additional flow was required? o (A) compound, pressure-relief valve (B) unloading valve o (C) counterbalance valve o (D) sequence valve 19. As shown in figure "B" of the typical ground fault relay shown in the illustration, what statement concerning the leakage current setting adjustment is true? Illustration EL-0223 o (A) Setting the leakage current for too high a value may increase the likelihood of nuisance trips and setting the leakage current for too low a value may result in incidental damage due to a ground fault. (B) Setting the leakage current for too low a value may increase the likelihood of nuisance trips and setting the leakage current for too high a value may result in incidental damage due to a ground fault. o (C) Setting the leakage current for too high or too low a value may increase the likelihood of nuisance trips. o (D) Setting the leakage current for too high or too low a value may result in incidental damage due to a ground fault. 20. An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of. o (A) spongy actuator movements o (B) aeration of the oil (C) pump cavitation o (D) contamination of the oil If choice C is selected set score to 1. Page 6 of 26

7 U.S.C.G. Merchant Marine Exam Illustrations: As shown in figure "A" of the digital multimeter screen shown in the illustration, what would be the significance of the symbol indicated by "1" being illuminated? Illustration EL-0047 o (A) the meter is subjected to a potentially unsafe voltage (B) the selector switch is selected for continuity/diode test and the secondary function push button is toggled for continuity o (C) the meter test leads are placed in the wrong terminal jacks for the test being performed o (D) the meter is in range of a wireless signal 22. Regarding an induction motor, what does the power developed by the rotor automatically adjust itself to? o (A) speed required to drive the load o (B) torque developed by the rotating field (C) power required to drive the load o (D) current flow in the motor stator If choice C is selected set score to By what means is an AC generator prevented from becoming motorized? o (A) overspeed trip (B) reverse power relay o (C) governor controls o (D) back pressure trip 24. What is one function of the movable cams in a drum-type winch motor controller? o (A) limit the amount of load put on the motor (B) regulate the speed of the motor o (C) maintain resistance contacts in clean condition o (D) insulate the operating handle 25. Why are removable sleeves installed on centrifugal pump shafts? o (A) They can be removed when it is necessary to lighten the weight of the pump. (B) They can be economically replaced as they wear out. o (C) They increase the strength of the shaft. o (D) They make it easier to replace the pump shaft packing. Page 7 of 26

8 U.S.C.G. Merchant Marine Exam Illustrations: Referring to the illustration what is the position of the three circuit breakers labeled in figure "A", "B", and "C" respectively? Illustration EL-0033 o (A) Circuit breaker in figure "A" is in the OFF position. Circuit breaker in figure "B" is in the TRIPPED position. Circuit breaker in figure "C" is in the ON position. o (B) Circuit breaker in figure "A" is in the ON position. Circuit breaker in figure "B" is in the TRIPPED position. Circuit breaker in figure "C" is in the OFF position. o (C) Circuit breaker in figure "A" is in the ON position. Circuit breaker in figure "B" is in the OFF position. Circuit breaker in figure "C" is in the TRIPPED position. (D) Circuit breaker in figure "A" is in the OFF position. Circuit breaker in figure "B" is in the ON position. Circuit breaker in figure "C" is in the TRIPPED position. If choice D is selected set score to According to the illustration, which of the following conditions would most likely cause pump "A" to short cycle? Illustration GS-0173 (A) The hydro-pneumatic expansion tank is operating with an insufficient air charge. o (B) The hydro-pneumatic tank is operating with a low water level. o (C) A low water level exists in the potable water storage tank. o (D) Pump "A" wearing rings have excessive clearance. 28. In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance? (A) phosgene gas o (B) carbon monoxide o (C) water vapor o (D) petroleum crystals 29. As shown in figure "B" of the illustrated self-contained recovery unit connection diagrams, what is the recovery method supported by the connection scheme? Illustration GS-RA-33 (A) direct vapor recovery o (B) direct liquid recovery o (C) liquid recovery/push-pull o (D) vapor recovery/push-pull Page 8 of 26

9 U.S.C.G. Merchant Marine Exam Illustrations: On most commercial cargo vessels with a relatively small crew size and few users of the potable water system, how is the potable water system pressure maintained? o (A) Cycling the potable water pump on and off by the action of the potable water storage tank level switches in response to system demand changes. o (B) Allowing the potable water pump to run continuously while recirculating during periods of zero demand for potable water. o (C) Allowing the potable water pump to run continuously against a shut-off head during periods of zero demand for potable water. (D) Cycling the potable water pump on and off by the action of the potable water hydro-pneumatic tank pressure switch in response to system demand changes. If choice D is selected set score to Which of the following bilge pumping applications would most likely use a non-automated centrifugal pump under manual supervision? o (A) Shaft alley bilges o (B) Machinery space bilges o (C) Engine room bilges (D) Dry cargo-hold bilges If choice D is selected set score to When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking? (A) the dielectric-absorption effect of the insulation o (B) good conductor resistance o (C) the inductive reactance of the windings o (D) the leakage of current along the surface of dirty insulation 33. Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system? o (A) Cooling the air to a temperature just above dew point. o (B) Heating the air and then cooling it to a point below dew point. (C) Cooling the air to a point below dew point, then reheating it. o (D) Heating the air to a point at which moisture will boil off, then recooling it. If choice C is selected set score to 1. Page 9 of 26

10 U.S.C.G. Merchant Marine Exam Illustrations: How are fuses usually rated? o (A) watts only o (B) amps only o (C) volts and amps only (D) volts, amps, and interrupting capacity If choice D is selected set score to No two drills from differing drill sets are of the exact same size, with the exception of the drills measured as 0.25 inch. These two drills are the 1/4 inch and the. o (A) "A" drill (B) "E" drill o (C) No.1 drill o (D) No.80 drill 36. What is the physical state and pressure condition of refrigerant as it leaves a receiver in a typical refrigeration system? o (A) high-pressure vapor (B) high-pressure liquid o (C) low-pressure vapor o (D) low-pressure liquid 37. Four incandescent lamps are connected in series in a single circuit. If one of the lamp filaments burns out, what will happen to the other lamps? (A) all go out o (B) become dimmer o (C) no change in brightness o (D) become brighter 38. In an electro-hydraulic steering system, damage due to rudder shock is prevented by. o (A) buffer springs (B) relief valves o (C) oil flowing through the pumps o (D) dashpots Page 10 of 26

11 U.S.C.G. Merchant Marine Exam Illustrations: Referring to the illustrated motor ship fresh water cooling system drawing, what statement is true concerning the jacket water heater? Illustration MP-CW-06 (A) The jacket water heater is used only when the engine is idle to keep the engine warm. o (B) The jacket water heater is used under low engine load conditions to provide supplemental heat for the evaporator. o (C) The jacket water heater is used only when the engine is idle for the sole purpose of generating fresh water at the evaporator. o (D) The jacket water heater is used under high engine load conditions to dissipate excess engine heat. 40. In a forced-feed lubrication system, what statement is true concerning lube oil reservoir/sump residence time? o (A) The lower the oil level, the longer the residence time, and the cooler the oil will be as delivered by the pump. (B) The lower the oil level, the shorter the residence time, and the hotter the oil will be as delivered by the pump. o (C) The lower the oil level, the longer the residence time, and the hotter the oil will be as delivered by the pump. o (D) The lower the oil level, the shorter the residence time, and the cooler the oil will be as delivered by the pump. 41. What is one major advantage of a diesel-electric propulsion plant? o (A) less maintenance o (B) lower fuel consumption (C) excellent maneuverability o (D) low cost and weight If choice C is selected set score to Which of the listed parts is used in a lobe-type rotary pump to allow for wear on the lobe edges? (A) Replaceable gib inserts o (B) Casing gear thrust bearings o (C) Spur gear adjusters o (D) Replaceable liner plates Page 11 of 26

12 U.S.C.G. Merchant Marine Exam Illustrations: Energy losses occurring in a hydraulic system are ultimately absorbed by the. o (A) reservoir expansion chamber (B) atmosphere as heat o (C) hydraulic piping flexibility o (D) fluid as friction 44. Concerning the charging of refrigerant into a vapor compression refrigerating system, which of the following is true? (A) when charging as a liquid it should be to the high side only o (B) when charging as a liquid it should be to the low side only o (C) when charging as a vapor it should be directly to the receiver only o (D) when charging as a liquid it may be to the low or high side 45. What is meant by the term "deadband" as it applies to prime mover speed control governors? o (A) Deadband is the repeated variation of speed due to under-control by the governor and a lack of governor power. (B) Deadband is the change in speed required before the governor will initiate a corrective action as the result of a load change. o (C) Deadband is the repeated and sometimes rhythmic variation of speed due to over-control by the governor. o (D) Deadband is the result of transient speed changes of a prime mover as the governor responds to load changes. 46. As shown in figure "A" of the illustrated block diagram of a central operating system configured for direct digital control, what does the output system block "ANALOG D/A" represent? Illustration EL o (A) It receives analog outputs from the CPU and converts these to digital signals for transmission to the digital actuators. o (B) It receives analog outputs from the CPU and conditions these to analog signals for transmission to the analog actuators. (C) It receives digital outputs from the CPU and converts these to analog signals for transmission to the analog actuators. o (D) It receives digital outputs from the CPU and conditions these to digital signals for transmission to the digital actuators. If choice C is selected set score to 1. Page 12 of 26

13 U.S.C.G. Merchant Marine Exam Illustrations: Which of the following statements represents the proper procedural sequence for adjusting the metering rate of an in-line lubricator as used in a ship's service air system hose station? Assume that the pressure regulator has been properly set. (A) Establish normal air flow. Determine drip rate. Further open needle valve to increase drip rate or further close needle valve to decrease drip rate, as appropriate. o (B) Establish normal air flow. Determine drip rate. Further open needle valve to decrease drip rate or further close needle valve to increase drip rate, as appropriate. o (C) Temporarily shut-off air flow. Determine drip rate. Further open needle valve to increase drip rate or further close needle valve to decrease drip rate, as appropriate. Re-establish normal air flow. o (D) Temporarily shut-off air flow. Determine drip rate. Further open needle valve to decrease drip rate or further close needle valve to increase drip rate, as appropriate. Re-establish normal air flow. 48. The component labeled "A" as shown in the illustration would be identified as the. Illustration GS-0175 o (A) oil content monitor probe o (B) separator vessel pressure relief valve (C) oil/water interface level sensing probe o (D) separator vessel vacuum breaker If choice C is selected set score to What effect will increasing the power source frequency have in a capacitive circuit? o (A) it will not have any effect on the average current value o (B) it will decrease the average current in the circuit (C) it will increase the average current in the circuit o (D) it will not have any effect on the capacitive reactance If choice C is selected set score to 1. Page 13 of 26

14 U.S.C.G. Merchant Marine Exam Illustrations: If an oil-in-water content monitor uses a lamp emitting light in the visible spectra in conjunction with a reference photocell and a sampling photocell, what is the operating principle upon which this oil-inwater content monitor works? o (A) The monitor works on the fluorescence principle where the greater the oil content, the less the amount of ultraviolet light detected by the sampling photoelectric cell as compared to the reference photoelectric cell. (B) The monitor works on the absorption/scattering principle where the greater the oil content, the less the amount of visible light detected by the sampling photoelectric cell as compared to the reference photoelectric cell. o (C) The monitor works on the fluorescence principle where the greater the oil content, the greater the amount of ultraviolet light detected by the sampling photoelectric cell as compared to the reference photoelectric cell. o (D) The monitor works on the absorption/scattering principle where the greater the oil content, the greater the amount of visible light detected by the sampling photoelectric cell as compared to the reference photoelectric cell. Page 14 of 26

15 National Maritime Center Providing Credentials to Mariners EL /1/2016 Adapted for testing purposes only Further reproduction prohibited without permission. Page 15 of 26

16 National Maritime Center Providing Credentials to Mariners EL /1/2016 Adapted for testing purposes only Further reproduction prohibited without permission. Page 16 of 26

17 National Maritime Center Providing Credentials to Mariners EL-0047 Adapted for testing purposes only from Fluke, Model 77 User s Manual, Fluke. Reproduced with permission from Fluke Corporation. Further reproduction prohibited without permission. 3/30/2015 Page 17 of 26

18 National Maritime Center Providing Credentials to Mariners EL /2/2016 Adapted for testing purposes only Further reproduction prohibited without permission. Page 18 of 26

19 National Maritime Center Providing Credentials to Mariners EL /6/2015 Adapted for testing purposes only from HUNT, Modern Marine Engineer s Manual, Vol. II Cornell Maritime Press. Reproduced with permission from Cornell Maritime Press, a division of Schiffer Publishing, Ltd. Further reproduction prohibited without permission. Page 19 of 26

20 National Maritime Center Providing Credentials to Mariners EL-0202 Adapted for testing purposes only from HUBERT, Operating, Testing and Preventive Maintenance of Electrical Power Apparatus Pearson Education Reproduced with permission from Pearson Education, Inc. 5/18/2015 Further reproduction prohibited without permission. Page 20 of 26

21 National Maritime Center Providing Credentials to Mariners EL /18/2015 Adapted for testing purposes only from MILLER/MILLER, Industrial Electricity and Motor Controls McGraw-Hill Reproduced with permission from Westinghouse Corporation. Further reproduction prohibited without permission. Page 21 of 26

22 National Maritime Center Providing Credentials to Mariners GS-0173 Adapted for testing purposes only from ROWEN, Introduction to Practical Engineering, Volume 2 Copyright 2005 by the Society of Naval Architects and Marine Engineers Further reproduction prohibited without permission Page 22 of 26 6/22/2016

23 National Maritime Center Providing Credentials to Mariners GS /24/2016 Adapted for testing purposes only from Heli-Sep Model 550/OCD Technical Manual Copyright by Coffin World Water Systems Further reproduction prohibited without permission Page 23 of 26

24 National Maritime Center Providing Credentials to Mariners GS-RA-01 2/17/2017 Adapted for testing purposes only from ALTHOUSE, Modern Refrigeration and Air Conditioning Copyright 1992 by The Goodheart-Willcox Company, Inc. Page 24 of 26 Further reproduction prohibited without permission

25 National Maritime Center Providing Credentials to Mariners GS-RA-33 4/14/2017 Adapted for testing purposes only from CARR, Refrigerants and the Environment Copyright 1993 by John Carr Page 25 of 26 Further reproduction prohibited without permission

26 National Maritime Center Providing Credentials to Mariners MP-CW-06 6/7/2016 Adapted for testing purposes only from HUNT, Modern Marine Engineer's Manual, Vol. II Copyright 2002 from Cornell Maritime Press, Inc. Further reproduction prohibited without permission Page 26 of 26