What Is A NM1GI?

What a NM1GI Actually Is

NM1GI refers to the National Master 100 GL and Inland credential: a U.S. mariner endorsement at the Master level for vessels under 100 gross register tons (GRT), operating on the Great Lakes and inland waters. In examination terms, the relevant NMC route is coded GLI06, titled "Master or Mate less than 100 GRT." The Master designation is the identity this site and this article focus on.

If you have seen other credentials that share the NM1GI letters, set them aside. Everything here is about the Coast Guard deck-officer pathway for smaller vessels on Great Lakes and inland routes. It is a licensing examination route, not a vendor certification, and the content is seamanship, safety, navigation, and rules, not software or IT.

For a related look at how the acronym is parsed, see What Does NM1GI Stand For?, and for the broader credential picture, NM1GI Certification.

Who Issues It and What the Route Code Means

The governing body is the United States Coast Guard National Maritime Center. The NMC publishes route pages that list which examination modules apply to a given endorsement. For this credential, the route page is GLI06, which bundles the module set for Master or Mate under 100 GRT on Great Lakes and inland waters.

The NMC Examination Guide behind these topic lists reflects regulations effective 2014-03-24. It should be used alongside the current published NMC module-topic index and your own approval to test. It is not a brand-new, universal examination specification. Official percentage weights are not published in the materials this article draws on, so the groups below are unweighted preparation groups, not a single common mandatory exam with fixed proportions.

For eligibility and prerequisites, the companion article NM1GI Requirements: Eligibility, Prerequisites & How to Qualify goes deeper.

The Five Preparation Groups

For a full-route original, the preparation load organizes into five groups. The Rules of the Road choice is counted once, because you take the version that matches your approved route, not both.

A deeper domain-by-domain walkthrough lives in NM1GI Exam Domains: Complete Guide to All 5 Content Areas. Here is the orientation version.

For how demanding these modules tend to feel in practice, read How Hard Is the NM1GI Exam? Complete Difficulty Guide.

The Rules of the Road Choice: Q100 or Q300

This is the most commonly misunderstood piece of the structure. The Rules module is offered in two flavors depending on your approved route:

• Q100: Rules of the Road, International and Inland
• Q300: Rules of the Road, Inland

You are not expected to prepare both and sit both. Your approval to test determines which one applies. The published topics under this heading are watchkeeping, COLREGS, and the Inland Navigational Rules. Candidates on a route that includes international scope should expect COLREGS content to carry weight; those on an inland-only route concentrate on the Inland Rules. Because the two rule sets differ in places, studying the wrong one is a real risk, which is why confirming your module code first is worth ten minutes before opening any book.

Great Lakes-Specific Topics and Why Route Matters

The NMC table marks certain Deck General topics with a footnote as Great Lakes-specific. Specifically, heavy weather operations and maneuvering for launching of lifeboats and liferafts in heavy weather carry that footnote. The practical implication: whether these topics show up depends on whether you are testing under a Great Lakes-and-Inland route or an Inland-only route.

That distinction is exactly why "Great Lakes-and-Inland versus Inland applicability" is a recurring theme in this credential. Two candidates holding the same study book can face different topic sets because their approved routes differ. If your approval is Inland only, spending a week on heavy-weather launching procedures may be effort you do not need; if your approval includes the Great Lakes, skipping them is a gamble. Check your approval, then allocate study time accordingly.

Where Q352 Fits (and Where It Doesn't)

Q352, Navigation and Deck General/Safety, is a separately listed module used for raise-of-grade routes. It is a consolidated module for candidates moving up from an existing endorsement, and it has its own NMC document.

Two common errors to avoid:

• It is not a universal sixth group. A full-route original candidate prepares the five groups above. Q352 is not appended to that list.
• It is not a second Rules subject. Despite touching navigation and general/safety material, it does not duplicate or replace the Q100/Q300 choice.

If your approval to test lists Q352, follow the NMC's own module document for that module. If it does not, leave it alone. Whether you are an original applicant or a raise-of-grade applicant changes what you sit, so confirm your category before building a plan. The timing and scheduling side is covered in NM1GI Exam Dates: Testing Windows, Deadlines & Scheduling.

Chart Plotting Q350: The Hands-On Module

The chart-plot module is where this credential differs most from a purely multiple-choice experience. Q350 is worked problem solving: you plot on a chart rather than only recognize a correct answer. The published topics cover:

• Piloting and distance-off problems
• Bearing problems
• Fix or running fix
• Chart navigation and dead reckoning
• Electronic navigation
• Instruments and accessories (dividers, parallel rules, plotting tools)
• Aids to navigation; charts, navigation publications, and Notices to Mariners

Notice the overlap with Q349: the same vocabulary (fix, running fix, distance off, dead reckoning) appears in both, but Q349 tests your understanding while Q350 tests your execution. Candidates who read about a running fix but never plotted one tend to lose time here.

Who Uses This Credential

A Master endorsement for vessels under 100 GRT on Great Lakes and inland routes is a working credential for operators of smaller commercial vessels. Typical settings include towing and barge operations on inland rivers and lakes, passenger and excursion boats, charter and fishing operations, dive and survey support boats, and harbor or ferry services. Employers in these segments commonly require a valid Coast Guard endorsement as a condition of putting you in command, since the credential is what makes you legally eligible to be in charge of the vessel.

Specific earnings depend heavily on employer, vessel type, seasonality, and region, and no reliable single figure applies across all of them. For a qualitative look, see NM1GI Salary Guide: Complete Earnings Analysis and NM1GI Jobs, and to weigh the investment, Is the NM1GI Certification Worth It? and NM1GI Certification Cost: Complete Pricing Breakdown.

Sequencing Your Preparation

Generic study methods matter less here than ordering the modules sensibly. Because the groups build on each other, a route-aware sequence helps:

For a fuller plan, see the NM1GI Study Guide: How to Pass on Your First Attempt and the quick-reference NM1GI Cheat Sheet. When you are ready to test yourself against realistic questions, the NM1GI practice test site lets you drill by module, and you can return to the main practice exam hub to check progress across all five groups.

Frequently Asked Questions

For related background on the credential's wording, you may also find What Is NM1GI? and NM1GI Meaning useful.