- What the National Master 100 NC Credential Actually Is
- Who Governs It and How Testing Works
- The Five-Module Structure
- Q100: Rules of the Road
- Q160: Deck General
- Q161: Deck Safety and Stability
- Q162: Navigation General, Near Coastal
- Q163: Chart Plot Problems
- Alternate Pathways You Should Not Confuse
- Sequencing Your Preparation
- Where the Credential Gets Used
- Frequently Asked Questions
- National Master 100 NC is a U.S. Coast Guard credential administered through the National Maritime Center (NMC).
- The original full exam uses five modules: Q100, Q160, Q161, Q162 and Q163.
- Q165 is a separate raise-of-grade module for OUPV holders, not part of the original five.
- Official percentage weights are not published, so treat each module as a full study block.
What the National Master 100 NC Credential Actually Is
National Master 100 NC is a U.S. Coast Guard mariner credential. In the Coast Guard's own exam catalog it appears as ONC06, Master Near Coastal, less than 100 GRT. It qualifies a licensed mariner to serve as master of vessels under 100 gross register tons operating in near coastal waters. The "100" is the tonnage ceiling, and "NC" is the near coastal route.
If you are new to the terminology, our explainers on what NM1N is and what NM1N stands for cover the naming in more depth. This article focuses on the certification itself: how the examination is built, what each module demands, and how to avoid the most common planning mistakes.
Who Governs It and How Testing Works
The governing body is the United States Coast Guard National Maritime Center. The NMC publishes module pages for each credential, plus an Examination Guide that lists the topics each module can draw from. Candidates do not simply choose an exam and sit it. You apply, the NMC evaluates your sea service and eligibility, and you receive an individual approval to test that specifies the modules you must pass.
That detail matters for planning. Two candidates holding the same target credential can be assigned different module sets depending on their existing licenses and the route they are on. Before you buy materials or book time off, read your approval carefully. For eligibility mechanics, see our guide to NM1N requirements and prerequisites.
On fees and timing: no single universal fee or exam timer applies across all routes, so be wary of any source that quotes one flat number. Our certification cost breakdown explains which cost categories exist without inventing totals, and the exam dates and scheduling guide covers how testing availability works in practice.
The Five-Module Structure
The original ONC06 full exam uses five modules. This is the structure the Coast Guard publishes for the less-than-100-GRT master near coastal credential:
| Module | Name | Core Character |
|---|---|---|
| Q100 | Rules of the Road: International and Inland | Watchkeeping, COLREGS, Inland Navigational Rules |
| Q160 | Deck General | Seamanship, maneuvering, firefighting, lifesaving, communications |
| Q161 | Deck Safety | Stability, construction, damage control, emergencies |
| Q162 | Navigation General: Near Coastal | Piloting, compass, aids to navigation, weather, tides |
| Q163 | Navigation Problems: Chart Plot | Worked chart problems and position determination |
The Coast Guard does not publish official percentage weights for these modules, so any pie chart claiming "Q162 is 30% of your score" is invented. Treat the groups as unweighted preparation blocks. Our complete domains guide walks through the same five areas from a different angle.
Q100: Rules of the Road
Rules of the Road: International and Inland (Q100)
The published topic list for this module is short but unforgiving: watchkeeping, COLREGS, and the Inland Navigational Rules.
- Know both rule sets, because a near coastal master crosses the demarcation line and must apply the correct regime on each side of it.
- Light and shape recognition, sound signals, and right-of-way relationships are tested as recall and application.
- Watchkeeping questions test judgment about lookout, speed, and risk of collision, not just memorized text.
Candidates often underestimate this module because the topic list is brief. The difficulty is that the International and Inland rules differ in specific, testable ways, such as signals used in meeting and crossing situations and certain whistle and light details. Study them side by side and note every divergence.
Q100 also has a role beyond the original five. For an increase in scope from Great Lakes or Inland to Near Coastal, the published guide uses Q160 plus Q162, and adds Q100 where a COLREGS limitation applies.
Q160: Deck General
This is the broadest module by sheer topic count. The published catalog spans seamanship, collision, marlinspike seamanship, temporary repairs, purchases, blocks and tackle, communications, ship's business, vessel maneuvering, and a long run of emergency and lifesaving subjects.
Deck General (Q160)
Think of Q160 as the practical seamanship and vessel-operations module.
- Maneuvering and handling: turn circle, pivot point, advance and transfer, and wake reduction.
- Emergency response: collision, fire or explosion, abandon ship procedures, rescuing survivors, and passenger and crew safety in emergencies.
- Fire knowledge: classes and chemistry of fire, basic firefighting and prevention, and firefighting appliances.
- Lifesaving and survival: lifesaving appliance operation, survival at sea, and storm, wreck, distress and special signals.
- Vessel business: certificates and documents required, communications, and radiotelephone procedure.
- Machinery basics: vessel power plants and small engine operations and maintenance.
Because the module is so wide, the study risk is depth versus breadth. You cannot memorize your way through marlinspike work and mechanical advantage; you need to understand how purchases, blocks and tackle trade force for distance. Likewise, maneuvering topics such as pivot point and transfer are conceptual, and rote answers fall apart when a question is framed from a new angle.
Q161: Deck Safety and Stability
Q161 is where the credential's stability content lives. The module's published topics include stability, construction and damage control, trim and stability, principles of vessel construction, emergency towing, man overboard procedures, and a repeat of several emergency subjects that also appear in Q160.
Deck Safety (Q161)
This module blends vessel-integrity knowledge with emergency procedure.
- Trim and stability: how loading, free surface and weight shifts affect a vessel, and how to recognize deteriorating stability.
- Construction and damage control: hull and structural principles, and how a crew contains flooding and damage.
- Man overboard and towing: recovery maneuvers and the mechanics of emergency towing.
- Abandon ship and rescue: procedures for leaving a vessel and for rescuing survivors from a ship or aircraft in distress.
- Machinery in emergencies: vessel power plants and small engine operation and maintenance.
Key Takeaway
Several subjects appear in both Q160 and Q161, including fire, abandon ship, rescue and power plants. Study those once, deeply, and then review them in each module's framing rather than treating them as four separate topics.
Q162: Navigation General, Near Coastal
Q162 is the theory half of the navigation block. Its published topics cover navigation and position determination, piloting, distance off, bearing problems, fix or running fix, chart navigation, dead reckoning, instruments and accessories, aids to navigation, and charts, publications and Notices to Mariners.
It also carries the compass and environmental material that Q163 does not:
- Compass: principles of the magnetic compass, magnetic compass error and correction, determination of compass error, and magnetic and gyro compasses.
- Terrestrial observation: using bearings and objects ashore to establish position.
- Meteorology and oceanography: characteristics of weather systems, ocean current systems, weather charts and reports.
- Tides and tidal currents: the data and reasoning needed to predict set, drift and water level.
Q162 is the module that most rewards fluency with actual publications and chart symbols. Reading a Notice to Mariners or interpreting an aid to navigation is a skill, not a fact, and it improves only through repetition against real references.
Q163: Chart Plot Problems
Q163 shares much of Q162's vocabulary, with piloting, distance off, bearing problems, fix or running fix, dead reckoning and aids to navigation, but it tests them as worked chart problems. It also includes electronic navigation, which is listed in Q163's published topics rather than Q162's.
Navigation Problems: Chart Plot (Q163)
This is the module where small errors compound.
- Plot courses and positions accurately, with correct use of instruments and accessories.
- Solve running fixes and bearing problems, including advance and distance-off calculations.
- Apply dead reckoning methodically, labeling every plotted line the way chart practice requires.
- Combine chart information, publications and Notices to Mariners into a defensible answer.
Many candidates who feel comfortable with the theory still stumble on Q163 because the work is procedural and unforgiving. The remedy is volume: plot problems repeatedly until your technique is automatic, then time yourself. For a view on relative difficulty across modules, read how hard the NM1N exam is, and for scoring thresholds see the passing score guide.
Alternate Pathways You Should Not Confuse
A frequent source of wasted effort is mixing up module sets from different routes. The Coast Guard publishes more than one path, and they must not be added together.
| Pathway | Modules | Notes |
|---|---|---|
| Original full exam, Master Near Coastal <100 GRT | Q100, Q160, Q161, Q162, Q163 | The five-module structure this article centers on |
| OUPV to Master Near Coastal <100 raise of grade | Q162 and Q165 per the published module page | Q165 Navigation and Deck General/Safety is separate and not part of the original five |
| Increase in scope, Great Lakes or Inland to Near Coastal | Q160 + Q162, plus Q100 where a COLREGS limitation applies | Per the published guide |
Sequencing Your Preparation
The five modules reward a specific order, because later material leans on earlier material. A sensible arrangement for the full ONC06 route:
Rules of the Road (Q100)
- Learn the International and Inland rules side by side and list every difference.
- Do this first because collision-avoidance reasoning appears again in Q160 and Q161 scenarios.
Deck General and Deck Safety (Q160, Q161)
- Study overlapping emergency topics once, then split into each module's framing.
- Give stability and trim extra time, since it is conceptual and easy to get wrong.
Navigation theory (Q162)
- Cover compass error, aids to navigation, weather and tides before plotting.
- Get comfortable with the publications you will use.
Chart plot (Q163)
- Practice timed plotting daily, finishing with full mixed problem sets.
- Review any weak theory from Q162 that surfaces during plotting.
For a fuller approach, our NM1N study guide expands on pacing, and the cheat sheet is useful for a final-days review once you have built the underlying understanding. You can also run timed drills on the NM1N practice test platform to see which modules need more attention.
Where the Credential Gets Used
A master near coastal credential for vessels under 100 GRT fits operators of smaller commercial and passenger vessels working along the coast: charter and excursion boats, fishing-related and workboat operations, towing and support vessels, and similar small-vessel work. Employers in these sectors typically care about the endorsement tonnage, the route, and your documented sea service rather than the acronym.
Pay and demand vary widely by region, vessel type and employer, and no single figure applies, so we avoid quoting numbers here. If you are weighing the investment, our salary analysis, the ROI discussion, and the jobs overview frame the decision qualitatively. For a look at outcomes, the pass rate article explains what is and is not known.
Key Takeaway
Treat your approval to test as the single source of truth. Confirm your module list with the NMC, build your plan around those exact modules, and use official NMC module pages and the Examination Guide as your reference for topic scope.
When you are ready to test your recall, the practice questions at the main NM1N Exam Prep site let you drill by module so you can see where your knowledge is thin before exam day.
Frequently Asked Questions
The original ONC06 Master Near Coastal less-than-100-GRT full exam uses Q100, Q160, Q161, Q162 and Q163. Q165 is a separate raise-of-grade module and is not part of that original five.
No. Official percentage weights are not published for these modules. Treat them as unweighted preparation groups and study each one thoroughly rather than relying on invented weighting figures.
Stability content sits within Q161, Deck Safety, alongside trim, construction, damage control and emergency topics. Older materials that describe a separate stability problems module belong to a different larger-vessel pattern.
Not necessarily. Raise-of-grade and increase-in-scope routes use different module combinations. Your individual approval to test from the National Maritime Center lists the modules you are required to pass.
No universal fee or timer applies across all routes, so rely on current NMC guidance for your specific application. For the cost categories involved, see our certification cost breakdown.