NM2GI Exam Domains 2026: Complete Guide to All 5 Content Areas

What National Master 200 GL and Inland Covers

National Master 200 GL and Inland (NM2GI) refers to the U.S. Coast Guard endorsement for Master or Mate of vessels less than 200 gross register tons on Great Lakes and Inland waters. The examination system sits under the United States Coast Guard National Maritime Center (NMC), and the scope code for this credential is GLI05. If you are still orienting yourself, start with What Is NM2GI? and then come back here for the exam structure.

This guide organizes the examination content into five route-aware preparation groups. That wording is deliberate. The NMC publishes examination modules and topic matrices, and the groups below follow those published module headings. They are not weighted blueprints, and this article does not assign percentages to any of them, because none are established in the source material. Treat each group as an area of knowledge to master, not a slice of a scoring pie.

The Five Module Groups at a Glance

For a full-route applicant, the module sets break down as follows. The only difference between the two routes is how Rules of the Road is satisfied.

Notice the structure. On the Great Lakes and Inland route, Rules of the Road comes through Q100. On the Inland route, you may use Q100 or Q300, with Q300 available when the applicable COLREGS limitation is accepted. In both cases you finish with five modules, not six. Anyone who adds Q100 and Q300 together is double counting.

The number of groups is also not a universal count of examinations for every applicant. Your NMC determination controls your assigned modules. For the broader picture of how the pieces fit into a study plan, see the NM2GI Study Guide 2026: How to Pass on Your First Attempt.

Domain 1: Rules of the Road (Q100 or Q300)

Why the choice matters

The decision between Q100 and Q300 is the single route-specific fork inside the full exam. It is not a matter of preference alone. It follows from the route you are applying for and whether the COLREGS limitation applies to you. If you are unsure which applies, resolve it before you build your study schedule, because Q100 is the broader of the two in scope while Q300 is confined to the inland rules.

What to master

Whichever module you take, the Rules of the Road material is about applying rules to situations, not reciting them in isolation. Expect to reason through steering and sailing rules, lights and shapes, sound signals, and responsibilities between vessels. Candidates preparing for Q100 should be ready to distinguish where inland and international rules differ, since the module covers both. Candidates on the Q300 path should concentrate on the inland body of rules and their specific signals and conventions.

Many applicants find this the most memorization-heavy part of the process, which is one reason it features in discussions of how hard the NM2GI exam is.

Domain 2: Deck General (Q340)

Deck General is where the written exam checks that you can run a deck, not just read a chart. Because the credential is for vessels under 200 gross register tons, the examples lean toward the kinds of vessels and operations common on lakes, rivers, and coastal-adjacent inland waters, such as towing, passenger, and charter work.

Prepare by connecting each concept to something physical. Stability, for instance, is easier to retain when you picture how loading and free surface affect a specific hull. Ship handling questions reward candidates who have actually felt wind, current, and shallow water push a vessel, so draw on your sea-service experience as you study. If your experience is thin in an area, supplement it deliberately with reading and drills.

Domain 3: Deck Safety (Q341)

Q341 is less about navigation and more about keeping people and the environment protected. A master is the person ultimately responsible when something goes wrong, so the module emphasizes knowing what equipment a vessel must carry, how it is used, and what to do in the first minutes of an emergency.

The strongest preparation is to learn the regulations and the reasoning behind them together. When you understand why a requirement exists, you can answer a scenario-based question even when the wording differs from what you studied. This is also a domain where checking the current published matrix pays off, since regulatory details are exactly what changes over time.

Domain 4: Navigation General: Great Lakes and Inland (Q342)

Navigation General is the knowledge layer beneath the chart plot. Where Q343 asks you to work a problem, Q342 asks whether you understand the tools and conditions behind it. Expect to interpret the information on a chart, apply the correct rules for aids to navigation on the waters in question, and account for the effects of current and weather on a vessel's track.

One important caution: alternative Rules or Navigation General modules must never be counted together as simultaneous requirements. For this route, the Navigation General module that applies is Q342. Other navigation modules you may encounter in NMC materials belong to different license routes and are not additional pieces of the full-original exam.

Domain 5: Chart Plot (Q343)

Chart Plot is the module candidates most often underestimate, because it rewards procedure and precision rather than recall. A correct answer depends on drawing lines accurately, reading scales carefully, and applying corrections in the right order. Small errors compound, so a slightly misread bearing can put you well off the right answer.

Practice this one with actual charts and plotting tools, not just by reading about the method. Build a routine: orient the chart, identify the scale and datum, apply variation and deviation correctly, then plot and check. Repetition is what turns a slow, error-prone process into a dependable one. The difficulty here is a major reason candidates read the NM2GI Cheat Sheet 2026 for quick procedural reminders, although a cheat sheet cannot replace hands-on plotting practice.

Modules That Are Not Extra Domains

The NMC publishes several other modules in the same family, and they are easy to mistake for additional requirements. Clearing this up prevents wasted study time and confusion about what you must pass.

Q345 is for applicants raising their grade, not for someone sitting the full original exam. Q346 serves a different starting credential and is likewise not an extra Master-original module. Separate upgrade, raise-of-grade, and route-extension modules are not additional full-original-exam domains. If you hold an existing credential and are upgrading, your approval to test may assign a different set than the five groups above, which is exactly why the individual NMC determination is the authority.

To confirm what qualifies you to apply in the first place, review NM2GI Requirements 2026: Eligibility, Prerequisites & How to Qualify.

Sequencing Your Preparation

The five groups differ in character, so the order you tackle them matters. The plan below is built around those differences rather than a generic schedule. Adjust the timing to your own availability and your assigned modules.

The logic is simple. Put memorization-heavy Rules of the Road first so it has time to settle through repeated exposure. Pair Deck General with Deck Safety because they share vocabulary and context. Place Navigation General before Chart Plot because plotting builds directly on the tools and conditions you learn in Q342. Finish with plotting drills when your foundation is strongest.

Once you have worked through the material, test yourself under realistic conditions with the NM2GI practice tests to find which module needs more attention. For more on pacing and approach, the NM2GI Study Guide 2026 goes deeper.

What to Confirm Before You Book

Because this article is built on published module headings rather than a single fixed exam specification, several details should be verified against your own paperwork rather than assumed.

• Your assigned modules. Use the actual NMC approval to test as the final word on what you will sit for.
• Format and timing. No single overall question count or duration is established for the whole credential, so rely on the information issued with your approval rather than figures from forums.
• Fees and scores. Current fees and any passing thresholds should come from the issuer, not from this article. For cost and scoring discussion, see NM2GI Certification Cost 2026 and NM2GI Passing Score 2026.
• Scheduling. Testing windows and logistics are covered in NM2GI Exam Dates 2026.

Be cautious with any source that quotes a single universal pass rate or a precise percentage weighting for each domain. Neither is established here, and the module-based structure makes such figures misleading. For a careful look at what the available evidence does and does not support, read NM2GI Pass Rate 2026: What the Data Shows.

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