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Basic NMEA 2000 Installer (BN2K): free practice test

Name: Basic NMEA 2000: the key concepts
Uploaded: 2026-11-13T01:30:12+00:00
Duration: 4 min 20 s
Description: Limits, power math and addressing rules the exam keeps testing. Drops are short, the backbone isn't; Two terminators read sixty ohms; Add LENs, then multiply; Feed power from the middle; Devices claim their own addresses; Different protocols always need a gateway.

NMEA's entry-level NMEA 2000 credential for installers, earned by passing the exam at the end of a one-day class. The class covers cables, connectors, specifications, physical planning and documentation, power distribution, voltage drop calculations, PGNs, connecting other data sources, network setup and troubleshooting, based on the NMEA 0400 Installation Standard. The certificate lasts 3 years and is the prerequisite for the Advanced NMEA 2000 class.

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Basic NMEA 2000: the key concepts

Limits, power math and addressing rules the exam keeps testing. Drops are short, the backbone isn't; Two terminators read sixty ohms; Add LENs, then multiply; Feed power from the middle; Devices claim their own addresses; Different protocols always need a gateway.

22 more lessons in PremiumThe full NMEA Basic NMEA 2000 (BN2K) video course, 4+ hours, rolling out to members

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Lesson 2: Why NMEA 2000 runs on CANMulti-talker, multi-listener design, the 250 kbit/s bus and certified product benefits.
Lesson 3: Micro, mid and mini cable gradesCable types, backbone length limits and current capacity of each grade.
Lesson 4: Five-pin connector and colour codeNET-S, NET-C, NET-H, NET-L and shield pins, O-rings and field-attachable connectors.
Lesson 5: Certified products and proprietary cablingReading the certification logo and joining branded networks with adapter cables.
Lesson 6: Building a linear backboneTees, multi-ports, inline terminators and why the backbone never branches.
Lesson 7: Drop cable rules in practiceSingle and cumulative drop limits, zero-length drops and when to extend the backbone.
Lesson 8: Termination: placement and testingWhere terminators go, built-in terminators and resistance readings for each fault.
Lesson 9: Planning the network on paperDiagramming backbone route, tee positions, drop lengths, LENs and the power tap.
Lesson 10: Routing and protecting network cablesSupport, chafe, heat, water and separation from high-current and antenna cables.
Lesson 11: As-built documentation and commissioningLabelling, NMEA 0400 checklists and records the next technician can use.
Lesson 12: Power taps and circuit protectionDedicated supply circuits, fusing and single versus split network power.
Lesson 13: Load Equivalency Numbers worked throughTotalling LENs across a real boat and checking against cable current limits.
Lesson 14: Voltage drop calculations step by stepRound-trip resistance, end-fed versus centre-fed networks and the nine-volt minimum.
Lesson 15: Shield, drain and groundingGrounding the shield at one point only and avoiding ground loops.
Lesson 16: 24-volt boats and isolated suppliesKeeping the network inside nine to sixteen volts on higher-voltage vessels.
Lesson 17: PGNs every installer should knowCommon navigation, engine and network management PGNs and what they carry.
Lesson 18: Address claim, NAME and priorityHow devices claim addresses, resolve conflicts and win bus arbitration.
Lesson 19: Single frames, fast-packet and transport protocolHow long messages are split and why product information matters.
Lesson 20: Gateways for NMEA 0183 and enginesBringing serial, J1939 engine and analog sender data onto NMEA 2000.
Lesson 21: Network setup: instances and data sourcesFirmware, device naming, instancing, preferred sources and calibration after installation.
Lesson 22: Troubleshooting the physical layerResistance, voltage under load and connector inspection in the right order.
Lesson 23: Isolating faults and missing dataSplitting the network, unsupported PGNs and configuration faults that mimic wiring faults.

Keep going after the free lesson. Every topic gets its own lesson, plus the full question bank, timed simulations and study tools.

About the NMEA Basic NMEA 2000 (BN2K) exam

What's on the exam

NMEA Basic NMEA 2000 (BN2K)

Cables, Connectors and Specifications

7 key facts

Backbone, Drops and Termination

7 key facts

Physical Planning and Documentation

6 key facts

Power Sources, Distribution and Voltage Drop

7 key facts

Data Messages (PGNs) and Addressing

7 key facts

Connecting Other Data Sources and Network Setup

6 key facts

Troubleshooting NMEA 2000 Networks

6 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 Basic NMEA 2000 (BN2K) exam

The pass mark is 80%: on a 50-question exam you can miss only 10. Know the hard numbers cold: 250 kbit/s, 50 connections, 100 m micro backbone, 6 m drop, 78 m total drops, 120 ohm terminators, 50 mA per LEN.
Expect at least one voltage drop calculation. Use the round-trip resistance of the power pair, multiply by the current, and check the far-end device still sees at least 9 V.
Termination questions are usually about where terminators go (the two physical ends of the backbone) and what a meter reads with power off (about 60 ohms between NET-H and NET-L).
Learn the five connector pins and wire colors: shield (bare), NET-S (red), NET-C (black), NET-H (white), NET-L (blue). Field-attachable connector questions test them directly.

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What's in the premium NMEA Basic NMEA 2000 (BN2K) prep

Premium NMEA Basic NMEA 2000 (BN2K) 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, 50 questions each, timed

800flashcards with spaced repetition, sorted by topic

60comprehensive key notes across 7 topics

Your step-by-step study path

1
Cables, Connectors and Specifications9 key notes, 115 flashcards, then 450 practice questions in 18 sets of 25
Notes free with an account
2
Backbone, Drops and Termination9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25
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3
Physical Planning and Documentation9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25
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4
Power Sources, Distribution and Voltage Drop9 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25
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5
Data Messages (PGNs) and Addressing8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25
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6
Connecting Other Data Sources and Network Setup8 key notes, 115 flashcards, then 425 practice questions in 17 sets of 25
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7
Troubleshooting NMEA 2000 Networks8 key notes, 110 flashcards, then 425 practice questions in 17 sets of 25
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Final step: 6 full mock exams50 questions each, timed like test day. Pass them, then book your exam.
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Read the complete NMEA Basic NMEA 2000 (BN2K) study notes for “Cables, Connectors and Specifications”

Our first full set of comprehensive notes, about 12 minutes of reading: What NMEA 2000 is · Network limits · Cable construction and ratings · The 5-pin connector · Certified versus compatible, 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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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.

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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.

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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 customer asks why you recommend an NMEA 2000 certified depth sensor over a cheaper unit sold as "NMEA 2000 compatible". What does NMEA certification actually confirm?

Answer: The product passed NMEA testing against the standard's network rules. Certification means NMEA's test tool and process checked the product against the NMEA 2000 standard (physical layer, network management and the messages it claims), which is what makes multi-brand networks reliable. It does not mean every display can show every PGN; the receiving device must also support that message.

2. Two NMEA 2000 devices start transmitting at exactly the same moment. How does the network decide which message is sent first?

Answer: The higher-priority identifier wins arbitration bit by bit. NMEA 2000 runs on CAN, which uses non-destructive bitwise arbitration: the frame with the lower identifier value (priority 0 is highest) keeps transmitting and the other backs off without losing data. Random-delay retry after a collision is how classic shared Ethernet works, not CAN.

3. You are fitting a field-attachable NMEA 2000 micro connector to a drop cable. Which conductor goes to the NET-H (CAN high) pin?

Answer: White. Standard colors: shield drain bare, NET-S (+ power) red, NET-C (power common) black, NET-H white, NET-L blue. Swapping white and blue is the classic field-connector mistake and stops that device communicating.

4. A chartplotter at the helm is 8 m from the nearest point the backbone can reach. What should the installer do?

Answer: Extend the backbone so the drop is 6 m or less. The maximum length of any single drop is 6 m, whatever the device. Joining drops just makes a longer drop. Run backbone cable and a tee closer to the helm instead, and remember the total of all drops is also limited (78 m).

5. On a 40 m backbone, an installer plans one terminator at the forward end of the backbone and the other on the end of the drop to the farthest instrument. Why is this wrong?

Answer: Terminators go only at the two ends of the backbone. NMEA 2000 needs exactly two 120-ohm terminators, one at each physical end of the backbone. A terminator on a drop leaves the backbone end unterminated and creates a long unterminated stub, causing reflections and errors.

6. Which items must a planning worksheet for a new NMEA 2000 network record so the design can be checked against the standard before any cable is cut?

Answer: Backbone and drop lengths, device LENs and the power tap point. Lengths, LENs and the power insertion point are what you need to check the cable limits, total current and voltage drop. Serial numbers and firmware are useful records afterwards but cannot tell you whether the network will work. NMEA 0400 also expects the finished network to be documented for the owner.

7. A network has three LEN 1 devices, four LEN 2 devices and two LEN 3 devices. How much current must the network power supply deliver?

Answer: 0.85 A. Total LEN = 3 + 8 + 6 = 17. One LEN is 50 mA, so 17 × 50 mA = 850 mA = 0.85 A. Answering 0.17 A treats one LEN as 10 mA; always convert LEN to current before checking cable ratings and voltage drop.

8. The power tap is at one end of a micro backbone. The power pair's round-trip resistance to the far end is 1.2 ohms, and 1.8 A of network load sits at that far end. The tap supplies 12.2 V. What voltage reaches the far-end devices?

Answer: 10.0 V. Drop = I × R = 1.8 × 1.2 = 2.16 V, so 12.2 − 2.16 ≈ 10.0 V. The 11.1 V answer uses only one conductor's resistance; current flows out on NET-S and back on NET-C, so use the round trip. Devices must still see at least 9 V.

9. On a long backbone powered from the bow end, network-powered instruments at the stern reset whenever heavy loads switch on. Which design change most directly reduces the network voltage drop?

Answer: Move the power insertion point near the center of the load. Feeding power near the electrical center of the load splits the current both ways along the backbone, so each half carries less current over a shorter distance and the drop falls sharply. Terminators carry no power, and LEN is a fixed rating of the device, not a setting.

10. Which PGN carries a GPS receiver's rapid position update (latitude and longitude) on NMEA 2000?

Answer: 129025. PGN 129025 is Position, Rapid Update. 127250 is vessel heading, 128267 water depth and 130306 wind data. A display that cannot show position from a new GPS often just lacks support for the PGN the sensor sends.

11. A new autopilot computer powers up and finds that another device already holds the source address it wants. What happens next?

Answer: The device with the higher-priority NAME keeps it; the other claims a new one. NMEA 2000 devices self-configure their addresses (0 to 251) through the ISO Address Claim (PGN 60928). When two claim the same address, the one whose 64-bit NAME has priority (lower value) keeps it and the other moves to a free address. No manual addressing is needed.

12. An older VHF radio accepts position only on an NMEA 0183 input, and the GPS is on the NMEA 2000 backbone. What is the correct way to get position to the radio?

Answer: Fit an NMEA 2000 to 0183 gateway and wire its output to the radio. NMEA 0183 is a different protocol (serial RS-422, usually 4800 baud) from NMEA 2000 (CAN, 250 kbit/s), so the two cannot be spliced together. A gateway translates the PGNs into 0183 sentences such as RMC or GGA for the radio.

13. After installation, the MFD's depth reading keeps switching between the bow sounder and the transom sounder. What setup step fixes this?

Answer: Choose a preferred depth source on the MFD. When two devices send the same data type, the display needs a selected (preferred) source, and the sensors should have unique instances so they can be told apart. All NMEA 2000 devices run at 250 kbit/s, and removing a terminator only creates errors.

14. With network power off, a meter between NET-H and NET-L at a tee reads close to 0 ohms. What is the most likely fault?

Answer: NET-H and NET-L are shorted together. A correctly terminated backbone reads about 60 ohms (two 120-ohm terminators in parallel), and a missing terminator reads about 120 ohms. Near 0 ohms means the data lines are shorted, for example by a crushed cable or a mis-wired field connector. Split the backbone to find the section.

15. Instruments near the transom drop off the network intermittently after washdowns. Termination resistance and network voltage test good when the boat is dry. What should you check first?

Answer: Connector seals and pins near the transom for water and corrosion. A fault that appears only when wet points to water entry: missing or damaged O-rings, connectors not fully tightened, or unsealed field connectors. Inspect and dry the connectors, look for green corrosion on the pins, and replace damaged parts. Firmware and LEN do not change with the weather.

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NMEA Basic NMEA 2000 (BN2K) exam FAQ

How many questions are on the NMEA Basic NMEA 2000 (BN2K) exam?

50 multiple-choice questions (NMEA states certification goes to class attendees who pass a 50-question exam; the BN2K page itself does not give the count), with a time limit of taken at the end of the training day. nmea does not publish a time limit for the initial exam; the renewal test is 50 questions with a 1-hour limit. Format: written multiple-choice exam after the class. the bn2k page does not say whether it is open book (nmea's basic mei and advanced mei exams are open book), so confirm with nmea. course materials include the nmea 2000 primer from the nmea 0400 installation standard.

What is the passing score for NMEA Basic NMEA 2000 (BN2K)?

80% or higher. One free proctored retake within 90 days; after that, re-attend the class at a 50% discount.

How much does the NMEA Basic NMEA 2000 (BN2K) exam cost?

US$520 NMEA member, US$1,040 non-member, for the class and exam. NMEA Trade membership includes one free installer course. Renewal every 3 years: US$100. ABYC charges members less than nonmembers, so confirm current fees with ABYC before you book.

Which languages is the NMEA Basic NMEA 2000 (BN2K) exam offered in?

English; NMEA also lists a Spanish-language Basic NMEA 2000 class.

Where do I take the NMEA Basic NMEA 2000 (BN2K) exam?

NMEA instructors, at the end of an 8-hour class taught virtual live or in person (see NMEA's training schedule); the exam is not sold on its own.

Is this NMEA Basic NMEA 2000 (BN2K) 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 Basic NMEA 2000 (BN2K) prep is Premium at $147 a month for this exam.

What's in the premium NMEA Basic NMEA 2000 (BN2K) prep?

3,000 practice questions organized topic by topic (Cables, Connectors and Specifications: 450; Backbone, Drops and Termination: 425; Physical Planning and Documentation: 425; Power Sources, Distribution and Voltage Drop: 425; Data Messages (PGNs) and Addressing: 425; Connecting Other Data Sources and Network Setup: 425; Troubleshooting NMEA 2000 Networks: 425), 6 full-length timed mock exams of 50 questions, 800 flashcards and 60 comprehensive key notes split across all 7 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.

Exam at a glance

Certifying body: National Marine Electronics Association (NMEA)
Test provider: NMEA instructors, at the end of an 8-hour class taught virtual live or in person (see NMEA's training schedule); the exam is not sold on its own
Questions: 50 multiple-choice questions (NMEA states certification goes to class attendees who pass a 50-question exam; the BN2K page itself does not give the count)
Time: Taken at the end of the training day. NMEA does not publish a time limit for the initial exam; the renewal test is 50 questions with a 1-hour limit
Passing score: 80% or higher. One free proctored retake within 90 days; after that, re-attend the class at a 50% discount
Format: Written multiple-choice exam after the class. The BN2K page does not say whether it is open book (NMEA's Basic MEI and Advanced MEI exams are open book), so confirm with NMEA. Course materials include the NMEA 2000 Primer from the NMEA 0400 Installation Standard
Fee: US$520 NMEA member, US$1,040 non-member, for the class and exam. NMEA Trade membership includes one free installer course. Renewal every 3 years: US$100

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