- What You Are Actually Preparing For
- Step Zero: Confirm Your Route and Assigned Modules
- The Six Preparation Groups at a Glance
- Rules of the Road: Q100 and Q300
- Deck General and Deck Safety: Q320 and Q321
- Navigation General: Q322
- Chart Plot: Q323
- Great Lakes Topics: Q324
- Sequencing Your Preparation by Module
- Module-Counting Mistakes That Derail Candidates
- Frequently Asked Questions
- The Great Lakes and Inland full route uses six modules: Q100, Q320, Q321, Q322, Q323 and Q324.
- The Inland-only route has five modules because it omits Q324 (Great Lakes Topics).
- Q100 and Q300 are alternatives for Rules of the Road; never count them as simultaneous requirements.
- Your NMC approval to test, not a general checklist, determines which modules you sit.
What You Are Actually Preparing For
National Master 500/1600 GL and Inland, abbreviated NM51GI on this site, is a U.S. Coast Guard mariner credential. The examination content is administered through the National Maritime Center (NMC), and the published module set for this credential is catalogued under the NMC code GLI03. If you are here to pass, the first thing to understand is that this is not a single monolithic test with one score, one timer and one question count. It is a set of issuer-published examination modules, and the ones you sit depend on your route.
This guide organizes those modules into unweighted, route-aware preparation groups. "Unweighted" matters: the published material does not hand candidates domain percentages, so anyone quoting you a neat percentage breakdown for this credential is inventing it. For background on the credential itself, see What Is NM51GI? and NM51GI Certification. For the full domain walkthrough, pair this article with NM51GI Exam Domains 2026: Complete Guide to All 6 Content Areas.
Step Zero: Confirm Your Route and Assigned Modules
Before opening a single study resource, determine which route you are on. The exact full-route module sets are:
| Route | Modules | Count |
|---|---|---|
| Great Lakes and Inland | Q100, Q320, Q321, Q322, Q323, Q324 | 6 |
| Inland | Q100 OR Q300, Q320, Q321, Q322, Q323 | 5 |
Two details trip people up. First, on the Inland route, Q100 and Q300 are alternatives, so you prepare for one Rules of the Road module, not both. Second, the Inland route omits Q324 entirely, which is why it has five modules rather than six. You cannot manufacture a "six" for an Inland candidate by double-counting Rules modules, and you should not drop Great Lakes Topics from a Great Lakes and Inland plan.
Separate modules exist for people upgrading or extending. Q326 (Navigation and Deck General/Safety) is a distinct raise-of-grade module for towing-to-Master-under-500 candidates. The guide also lists Inland-to-Great-Lakes-and-Inland route extension separately, pointing to Q324 (and Q100 where a COLREGS limitation applies). These are not additional full-original-exam domains. If you are in one of those categories, your assigned list will look different from the table above.
Key Takeaway
Your individual approval to test from the NMC is the authority on which modules you sit. Build your study plan from that document, not from a forum post about someone else's route. If your requirements are unclear, start with NM51GI Requirements 2026: Eligibility, Prerequisites & How to Qualify.
The Six Preparation Groups at a Glance
For a Great Lakes and Inland candidate, the six groups map to six modules. Here they are in one place, with the specific content areas the NMC publishes for each where available.
| Group | Module | Route |
|---|---|---|
| Rules of the Road: Inland and International | Q100 (Q300 is the Inland-only alternative) | Both routes |
| Deck General | Q320 | Both routes |
| Deck Safety | Q321 | Both routes |
| Navigation General: Great Lakes and Inland | Q322 | Both routes |
| Navigation Problems: Chart Plot | Q323 | Both routes |
| Great Lakes Topics | Q324 | Great Lakes and Inland only |
Notice the structure: five groups are shared, one is route-specific. That shapes how you should spend your time, which we cover in the sequencing section below.
Rules of the Road: Q100 and Q300
Domain 1: Rules of the Road: Inland and International (Q100)
This group covers collision-avoidance rules. Q100 addresses both Inland and International rules; Q300 is the Inland-only alternative applicable to the restricted route. Which one you are assigned depends on your route and any COLREGS limitation on your credential.
- Know the difference between Inland and International rules, not just the shared core.
- Master steering and sailing rules, lights, shapes and sound signals.
- Be fluent in right-of-way relationships between vessel types.
- If you are on the Inland-only route and assigned Q300, do not spend hours on International-only material unless your assignment requires it.
A common mistake is treating Rules as "common sense." The modules reward precise recall of rule wording and the differences between the two rule sets. If you have limited time, drill the places where Inland and International differ, because that is where otherwise strong mariners lose points.
Deck General and Deck Safety: Q320 and Q321
These two modules are the broad seamanship foundation. They are separate modules, so plan for separate study blocks rather than blending them into one "deck" bucket.
Domain 2: Deck General (Q320)
General deck knowledge expected of a Master of vessels under 500/1600 GRT: vessel operations, construction and general seamanship concepts as they apply to this credential tier.
- Review the published topic matrix on the NMC page for GLI03 and tick off each heading.
- Connect each topic to real operations you have performed; the exam favors applied understanding.
Domain 3: Deck Safety (Q321)
Safety-focused knowledge for the Master's responsibilities, including vessel safety practices and emergency considerations relevant to this license level.
- Study safety topics as decision-making scenarios, not just definitions.
- Cross-check regulatory references against current published sources.
Navigation General: Q322
Domain 4: Navigation General: Great Lakes and Inland (Q322)
This module covers navigation knowledge specific to Great Lakes and Inland waters, as distinct from the hands-on plotting work in Q323.
- Understand aids to navigation and their application on these waters.
- Know the publications and chart-related references a Master is expected to use.
- Separate theory here from the plotting mechanics tested in the chart plot module.
Keep Q322 and Q323 mentally distinct. Candidates sometimes assume that strong chart-plotting skills carry them through the general navigation module, or vice versa. They are different skills tested in different modules.
Chart Plot: Q323
Domain 5: Navigation Problems: Chart Plot (Q323)
A problem-solving module. Expect to work navigation problems on a chart rather than recall definitions, which makes it the most skill-dependent group.
- Practice plotting under time pressure; accuracy and speed both matter.
- Work problems end to end: set up, plot, solve, then verify your answer for reasonableness.
- Keep your plotting tools and technique consistent so you are not improvising on test day.
Great Lakes Topics: Q324
Domain 6: Great Lakes Topics (Q324), Great Lakes-and-Inland route only
This is the module that distinguishes the Great Lakes and Inland credential from Inland-only. The published topic list covers material specific to Great Lakes operations.
- Piloting and compass error.
- Meteorology and oceanography as they apply to the Lakes.
- Maneuvering and handling, including ice.
- Stability, construction and damage control.
- Cargo handling.
If you are on the Inland-only route, you do not sit Q324 and can skip this entire section of your preparation. If you are on the full Great Lakes and Inland route, do not shortchange it because it appears last in the list. Its topics are broad and distinct from the other modules, and a candidate who treats it as an afterthought often discovers the gap too late. If you are weighing whether the broader credential is worth the added module, read Is the NM51GI Certification Worth It? Complete ROI Analysis 2026.
Sequencing Your Preparation by Module
Because the modules are unweighted, allocate effort by your own weaknesses and by the skill type of each module, not by guessed percentages. The timeline below assumes the full six-module Great Lakes and Inland route; Inland-only candidates simply drop the Q324 block and lengthen the others.
Rules of the Road (Q100 or Q300) and Chart Plot (Q323) start
- Begin Rules early because precise recall needs repeated exposure.
- Start plotting practice immediately, since speed is a skill built slowly.
Deck General (Q320) and Deck Safety (Q321)
- Work through the published topic matrix heading by heading.
- Keep plotting practice running a few sessions per week.
Navigation General (Q322) and Great Lakes Topics (Q324)
- Study Q322 as theory distinct from your Q323 plotting work.
- Give Q324 its own dedicated block covering each published topic area.
Integration and weak-point review
- Run timed practice across all assigned modules.
- Return to the module where your accuracy is lowest.
Use the practice platform at our main practice test site to check retention after each block, and keep a one-page summary handy with the NM51GI Cheat Sheet 2026: One-Page Review of Must-Know Facts. Practice questions are for building recall and test-taking rhythm; they are not a substitute for the issuer's published topic lists, and no study material here is endorsed by the Coast Guard or NMC.
Module-Counting Mistakes That Derail Candidates
Most first-attempt problems on this credential are planning errors, not knowledge errors. Watch for these:
- Counting Q100 and Q300 together. They are alternatives. Preparing for both wastes time and misrepresents your requirement.
- Dropping Q324 from a Great Lakes and Inland plan. The full route has six modules. Skipping Great Lakes Topics is not an option on that route.
- Inflating an Inland route to six. The Inland route is five modules. Do not add phantom requirements.
- Treating Q326 as part of the full original exam. It is a separate raise-of-grade module for a different applicant category.
- Assuming a single question count or time limit. The published material does not establish one overall figure, so rely on what the NMC tells you for your assigned modules.
- Quoting fees or pass rates from memory. Current fees and population pass rates are not established in the published module material. Check the NMC for fees, and read NM51GI Pass Rate 2026: What the Data Shows and NM51GI Certification Cost 2026: Complete Pricing Breakdown with that caution in mind.
Key Takeaway
Preparation for this credential is route-aware. Write down your exact assigned module list first, then build your study blocks around it. Scoring and scheduling details are covered in NM51GI Passing Score 2026: Exactly What You Need to Pass and NM51GI Exam Dates 2026: Testing Windows, Deadlines & Scheduling, but always confirm the current specifics with the NMC.
Frequently Asked Questions
On the full Great Lakes and Inland route, six: Q100, Q320, Q321, Q322, Q323 and Q324. On the Inland route, five, since Q324 is omitted and Q100 or Q300 serves as the Rules module. Your NMC approval to test confirms your actual assignment.
No. They are alternatives for the Rules of the Road requirement. Q100 covers Inland and International rules, while Q300 is the Inland-only alternative for the restricted route. Never count them as simultaneous requirements.
No. Q326 (Navigation and Deck General/Safety) is a separate raise-of-grade module for towing-to-Master-under-500 applicants. It is not an additional domain of the full original exam.
The packet behind this guide does not establish domain percentages, so this guide treats the groups as unweighted. The NMC does publicly post module headings and topic matrices, which are the right place to confirm scope.
Start by confirming your route and assigned modules, then read the credential overview in What Does NM51GI Stand For? and review training options in NM51GI Training. From there, build a module-by-module plan and use the practice tests to track progress.
A Master credential at this tier relates to command of vessels on Great Lakes and Inland waters. For a look at the employment side, see NM51GI Jobs and the earnings discussion in NM51GI Salary Guide 2026: Complete Earnings Analysis.