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NMEA · Last updated November 2026

Certified Marine Electronics Technician (CMET): free practice test

NMEA's highest certification for marine electronics technicians. The exam draws on the NMEA 0400 Installation Standard, FCC General Radio Operator material and field knowledge of radar, satcom, GPS, autopilots, AIS, VHF and DSC, SSB, NMEA 0183, NMEA 2000, Ethernet, transducers, RF and power distribution. CMETs hold the FCC licenses needed to repair ship radio and radar transmitters.

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About the NMEA CMET exam

NMEA's highest certification for marine electronics technicians. The exam draws on the NMEA 0400 Installation Standard, FCC General Radio Operator material and field knowledge of radar, satcom, GPS, autopilots, AIS, VHF and DSC, SSB, NMEA 0183, NMEA 2000, Ethernet, transducers, RF and power distribution. CMETs hold the FCC licenses needed to repair ship radio and radar transmitters.

What's on the exam

NMEA CMET
NMEA 0400 Installation and Power Distribution
7 key facts
Electrical and RF Principles
7 key facts
NMEA 0183, NMEA 2000 and Ethernet
7 key facts
Radar
7 key facts
GPS, Heading Sensors and Autopilots
7 key facts
VHF, DSC, AIS, SSB and FCC Rules
7 key facts
Satcom, Sat TV, Wi-Fi, MFDs and Computers
7 key facts
Transducers and Hydroacoustics
7 key facts

Each branch is a topic in the official outline. Members see every key fact on the full mind map. Read the free study guide →

How to pass the NMEA CMET exam

  • 150 questions in 120 minutes is 48 seconds each. Bank the quick recall items (channel numbers, PGNs, cable limits) to leave time for dB, VSWR and wire-size calculations.
  • 80% means you can miss only 30 questions. Breadth matters: the pool spans more than 20 subject areas, so don't skip satcom or hydroacoustics because you rarely install them.
  • NMEA says the exam is built on experience. For troubleshooting stems, choose the step a careful technician would take first, usually measuring before replacing.
  • Apply for the exam early: NMEA advises paying the application fee about six months ahead so you have time to work through the NMEA 0400 standard and radar material it sends.

Save your results and get your Readiness Score

Create a free account after the test: your score by topic, a mistakes bank, the complete study notes for the first topic, flashcards and the ABYC Numbers & Formulas Sheet.

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What's in the premium NMEA CMET prep

Premium NMEA CMET prep is studied one topic at a time. Each step starts with that topic's key notes and flashcard deck, then its own question sets of 25, so you master one topic before you move to the next. When every topic is strong, the 6 full mock exams show you're ready.

3,000practice questions, every answer explained
6full-length mock exams, 150 questions each, timed
800flashcards with spaced repetition, sorted by topic
60comprehensive key notes across 8 topics

Your step-by-step study path

  1. 1
    NMEA 0400 Installation and Power Distribution8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Notes free with an account
  2. 2
    Electrical and RF Principles8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
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  3. 3
    NMEA 0183, NMEA 2000 and Ethernet8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  4. 4
    Radar8 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  5. 5
    GPS, Heading Sensors and Autopilots7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  6. 6
    VHF, DSC, AIS, SSB and FCC Rules7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  7. 7
    Satcom, Sat TV, Wi-Fi, MFDs and Computers7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  8. 8
    Transducers and Hydroacoustics7 key notes, 100 flashcards, then 375 practice questions in 15 sets of 25
    Premium
  9. Final step: 6 full mock exams150 questions each, timed like test day. Pass them, then book your exam.
    Premium
Free with an account

Read the complete NMEA CMET study notes for “NMEA 0400 Installation and Power Distribution”

Our first full set of comprehensive notes, about 14 minutes of reading: Conductors and connections · Sizing conductors for voltage drop · Circuit protection and distribution · Interference and routing · Documentation and handover, a worked exam example, the traps examiners use and a one-minute recap. Create a free account to read it and see how premium notes work before you decide.

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Study tools included

3,000 practice questions

3,000 exam-style questions per exam, organized topic by topic in sets of 25. Every answer explained, with the rule it comes from.

6 full mock exams

6 full-length timed mock exams per exam, with real question counts and time limits, so test day feels like practice day.

Exam Readiness Score

One 0 to 100 number that tells you when you're ready to book. Reach 80 and you're covered by our Pass Guarantee.

800 flashcards + spaced repetition

800 flashcards per exam, in a deck for each topic, that come back right before you'd forget them. Five minutes a day keeps every number fresh.

60 comprehensive key notes

60 key notes per exam, split across its topics and each explained in full: the concepts, worked exam examples, the traps examiners use and a quick recap. Your first set is free with an account.

Mind maps

See the whole exam on one screen: every topic and the facts under it.

Sample questions with answers

These are the questions in the free test above, with answers. Try the test first. You'll learn more by getting some wrong.

1. A radar draws 8 A at 12 V and is 25 ft (one way) from the electronics distribution panel. Using the 3% voltage-drop limit and CM = (10.75 × I × L) ÷ E, what is the smallest copper conductor that meets the limit?
Answer: 8 AWG. L is the round-trip length, 50 ft, and E is 3% of 12 V, 0.36 V: 10.75 × 8 × 50 ÷ 0.36 = about 11,900 circular mils. 10 AWG is only 10,380 CM, so 8 AWG (16,510 CM) is the smallest that works. Using the one-way length is the classic error that points to 10 AWG.
2. NMEA 2000 and NMEA 0183 cables must pass an inverter's AC output cable on the way to the helm. Which routing best limits coupled interference?
Answer: Cross the AC cable at right angles, spaced away. Coupling is greatest where conductors run parallel and close, so data cables should be kept apart from AC and high-current wiring and cross it at 90 degrees. Bundling them together maximizes coupling, and grounding shields at both ends creates ground loops; NMEA 2000 shields are grounded at one point only.
3. A VHF antenna with a 75-ohm feed-point impedance is connected to a 50-ohm coax line. What VSWR results?
Answer: 1.5:1. Reflection coefficient = (75 − 50) ÷ (75 + 50) = 0.2, and VSWR = (1 + 0.2) ÷ (1 − 0.2) = 1.5:1. A quick check is the ratio of the two impedances, 75 ÷ 50 = 1.5. Results of 2:1 or more usually point to a fault in the antenna, connector or cable.
4. A 25 W VHF transmitter feeds an antenna rated at 6 dB gain through a coax run with 3 dB of loss. What is the approximate effective radiated power?
Answer: 50 W. Net gain is 6 − 3 = +3 dB, and +3 dB doubles power, so 25 W becomes about 50 W ERP. Each 3 dB is a factor of two and each 10 dB a factor of ten. Forgetting to subtract the cable loss gives 100 W.
5. With the NMEA 2000 network powered off, a meter across CAN_H and CAN_L at a tee reads about 120 ohms. What does this indicate?
Answer: One terminator is missing or disconnected. Two 120-ohm terminators in parallel read about 60 ohms. A 120-ohm reading means only one is in circuit, so a terminator is missing or a backbone section is open. About 40 ohms means three terminators; near zero means a short between the data lines.
6. A chartplotter's NMEA 0183 input shows garbled characters after a Class B AIS transponder is wired to it. The plotter port is set to 4800 baud. What is the most likely fix?
Answer: Change the port to 38,400 baud (high speed). AIS units output VDM and VDO sentences at 38,400 baud (NMEA 0183-HS) because 4800 baud can't carry the traffic. A baud mismatch produces garbled or no data, so set the port to match. Reversed polarity usually gives no data at all, and 120-ohm terminators belong on NMEA 2000, not a 0183 listener.
7. A new NMEA 2000 sensor draws 330 mA from the network. What Load Equivalency Number (LEN) should it carry?
Answer: 7. One LEN equals 50 mA, rounded up: 330 ÷ 50 = 6.6, so LEN 7. The total LEN on each side of the power insertion point is used to check network voltage drop, so rounding down understates the load.
8. A radar transmits a 0.5-microsecond pulse. Ignoring receiver and display limits, what is the closest range separation at which two targets on the same bearing show as separate echoes?
Answer: 75 m. Range resolution is c × pulse length ÷ 2: 300 m per microsecond × 0.5 ÷ 2 = 75 m, which is 150 m per microsecond of pulse. Shorter pulses on short ranges improve resolution; longer pulses on long ranges put more energy on target.
9. A radar scanner is 16 ft above the water. Using the radar horizon formula with standard refraction, at roughly what range could it first detect the top of a target 36 ft high?
Answer: 12.2 nm. Radar horizon in nautical miles is about 1.22 × √(height in feet) for each end: 1.22 × (√16 + √36) = 1.22 × 10 = 12.2 nm. Using only the antenna height gives 4.9 nm. Raising the scanner helps less than people expect because range grows with the square root of height.
10. After a refit, radar overlay on the MFD smears and MARPA targets wander. Heading comes from a fluxgate sensor through an NMEA 0183 HDG sentence at 1 Hz. What is the best correction?
Answer: Supply heading at about 10 Hz via NMEA 2000. Radar overlay, MARPA and autopilots need a fast, stable heading, typically 10 updates per second, such as NMEA 2000 PGN 127250. A 1 Hz heading makes the overlay lag as the boat yaws. A faster GPS fix doesn't help because the radar picture is rotated by heading, not position.
11. The autopilot's fluxgate heading jumps about 15 degrees each time the bow thruster runs, then returns. What is the right fix?
Answer: Move the sensor away from the thruster's DC cables. A transient error that tracks a high-current load is the magnetic field around its DC cables. Calibration only removes fixed deviation, and damping just slows the display. Mount heading sensors low, near the center of motion, and well away from ferrous metal and current-carrying conductors.
12. A technician with a GROL is asked to replace the magnetron and adjust the transmitter of a radar on a commercial fishing vessel. What does FCC licensing require?
Answer: A Ship Radar Endorsement on the license. Only a person whose commercial license carries the Ship Radar Endorsement (Element 8) may repair, maintain or internally adjust ship radar. The GROL (Elements 1 and 3) covers maritime radiotelephone transmitters but not radar. This is why CMET requires Elements 1, 3 and 8.
13. A test DSC call from a new fixed VHF reaches the receiving station with no position. The MMSI is programmed correctly. What should be checked first?
Answer: The GPS position feed into the radio. A DSC radio sends its position only when it has a valid fix from a connected GPS (NMEA 0183 or NMEA 2000) or an internal receiver. Without one, a distress alert goes out with no position, which slows rescue. Antenna gain and power affect range, not the position field.
14. A stabilized satellite TV dish on a yacht loses signal only on certain headings, and the problem gets worse as the boat cruises north. What is the most likely cause?
Answer: Blockage by the mast or arch at low elevation. Geostationary satellites sit over the equator, so their elevation angle falls as latitude increases. At low elevations the mast, radar arch or flybridge blocks the beam on headings that put them in the line of sight. A polarization, cable or satellite setting fault would affect every heading.
15. A sounder measures 0.02 seconds between transmitting a pulse and receiving the bottom echo in seawater. What is the depth below the transducer?
Answer: 15 m. Depth = speed of sound × time ÷ 2. In seawater, sound travels about 1,500 m/s: 1,500 × 0.02 ÷ 2 = 15 m. Forgetting to halve for the round trip gives 30 m. Fresh water is slower, about 1,435 m/s, so readings differ slightly.

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NMEA CMET exam FAQ

How many questions are on the NMEA CMET exam?

150 multiple-choice questions drawn from a pool of nearly 500 shared with the NMET exam, with a time limit of 2 hours. Format: proctored multiple choice with a standard calculator allowed. nmea states the identical nmet exam is closed book. prerequisites: current amei and advanced nmea 2000 certificates, and for us applicants an fcc grol with ship radar endorsement (fcc elements 1, 3 and 8). this prep covers the knowledge exam only, not the fcc element exams.

What is the passing score for NMEA CMET?

80% (120 of 150).

How much does the NMEA CMET exam cost?

US$100 for NMEA members, US$300 for non-members, including one retake within 60 days. FCC element exam fees are separate (NMEA is an FCC test center). Renewal every 5 years: US$100. ABYC charges members less than nonmembers, so confirm current fees with ABYC before you book.

Which languages is the NMEA CMET exam offered in?

English (NMEA does not publish other language options).

Where do I take the NMEA CMET exam?

Proctored by NMEA: online with NMEA staff, by mail to a library, learning center or college you nominate, at the NMEA Conference, or at the NMEA office in Severna Park, Maryland. Book at least 2 weeks ahead.

Is this NMEA CMET practice test free?

Yes. The 15-question practice test on this page is free, with an explanation for every answer and no signup. A free account also unlocks the complete study notes for the first topic. The full NMEA CMET prep is Premium at $147 a month for this exam.

What's in the premium NMEA CMET prep?

3,000 practice questions organized topic by topic (NMEA 0400 Installation and Power Distribution: 375; Electrical and RF Principles: 375; NMEA 0183, NMEA 2000 and Ethernet: 375; Radar: 375; GPS, Heading Sensors and Autopilots: 375; VHF, DSC, AIS, SSB and FCC Rules: 375; Satcom, Sat TV, Wi-Fi, MFDs and Computers: 375; Transducers and Hydroacoustics: 375), 6 full-length timed mock exams of 150 questions, 800 flashcards and 60 comprehensive key notes split across all 8 topics, plus a mistakes bank and the Readiness Score.

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Exam details are summarized from the official candidate information available in November 2026. ABYC changes formats and fees, so confirm with National Marine Electronics Association (NMEA) before you book. ABYCExamPrep is not affiliated with the American Boat & Yacht Council.

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