- USCG-CM-UNL here means National Chief Mate Unlimited, Oceans or Near Coastal, examined through the USCG National Maritime Center.
- The ONC01 exam draws on modules Q100 through Q109, but not every candidate sits all ten.
- Q105 and Q106 are route alternatives: Near Coastal navigation versus Oceans navigation.
- Your USCG approval-to-test, not a study guide, determines which modules you are assigned.
What the Credential Actually Is
USCG-CM-UNL, as used on this site, stands for the National Chief Mate Unlimited, Oceans or Near Coastal endorsement. It is a United States Coast Guard credential for officers who will serve as chief mate on merchant vessels of unlimited tonnage. Chief mate is the second-in-command of the deck department, so the examination reflects that role: it tests command-level knowledge of navigation, cargo, stability, safety, and the legal framework for operating a large vessel.
Unlike many industry certifications, this is not a vendor exam with a single fixed outline sold off a shelf. It is a regulatory examination tied to a mariner credential. The content is defined by the Coast Guard, the modules you sit depend on the route of your endorsement, and the outcome feeds directly into whether you can hold the rating at all. If you want the broader framing of terms before going further, the explainers on what USCG-CM-UNL stands for and the meaning of the designation cover the vocabulary.
Who Governs It and How Testing Works
The governing body is the United States Coast Guard National Maritime Center (NMC). The NMC publishes the official exam topic lists for the oceans and near coastal endorsements, including the ONC01 chief mate module outlines. Those lists are the authoritative source for what can appear on your exam. The topics are published as unweighted lists, meaning the Coast Guard does not publish percentage weights per module the way some commercial certifications do. Treat any site that claims precise domain percentages for this exam with skepticism.
The practical mechanics center on approval to test. After your application and sea service are evaluated, the Coast Guard authorizes you to examine and assigns the modules you must pass. That assignment, not a generic checklist, defines your actual exam. For eligibility and sea-service questions, see our guide to USCG-CM-UNL requirements, and for the money side, the certification cost breakdown explains what to budget for. Confirm all fees and scheduling directly with the NMC and your regional exam center, since those details are administrative and can change.
The ONC01 Module Map: Q100 Through Q109
The Coast Guard organizes chief mate examination content into ten modules. This site presents them as ten content domains, and the full walkthrough lives in our complete guide to all 10 content areas. Here is the substance of each, drawn from the official module topics.
Domain 1: Q100 Rules of the Road - International and Inland
The COLREGS and the Inland Rules, applied to safe watchkeeping.
- Steering and sailing rules, lights, shapes, and sound signals
- Knowing which rule set governs where you are operating
- Applying the rules to collision-avoidance scenarios on watch
Domain 2: Q101 Deck General Part I
The seamanship and management side of the job.
- Maneuvering and handling, including pilot stations
- Rivers, estuaries, and shallow-water effects
- Maritime law and credentialing
- Shipboard management and personnel training
Domain 3: Q102 Deck General Part II
Watchkeeping principles, regulation, and cargo.
- Basic principles and watchkeeping
- Navigation safety requirements under 33 CFR 164
- Cargo handling and stowage
Domain 4: Q103 Deck Safety
Vessel integrity, emergencies, and lifesaving.
- Construction, stability, trim, and damage
- Grounding, refloating, collision, and temporary repairs
- Passenger safety, fire, and abandoning ship
- Emergency steering and lifesaving rules and operation
- Search and rescue, including AMVER and IAMSAR
Domain 5: Q104 Deck Safety/Stability Problems
The quantitative companion to Q103.
- Trim and stability calculations
- Damage stability
- Stress calculations
Domain 6: Q105 Navigation General - Near Coastal
Coastal and piloting-oriented navigation knowledge.
- Piloting, distances, bearings, fixes, charts, and dead reckoning
- Instruments, aids, publications, and notices
- Magnetic and gyro compass error correction
- Azimuth, amplitude, and terrestrial fixes
- Meteorology, weather, ocean currents, reports, and tides
Domain 7: Q106 Navigation General - Oceans
The same navigation foundation, extended into celestial work.
- Relevant piloting, charts, instruments, compass, weather, and tides
- Nautical astronomy and celestial navigation
- Polaris, fixes, star identification and selection, and meridian transit
Domain 8: Q107 Chart Plot
Hands-on chartwork under exam conditions.
- Piloting, chart fixes, and dead reckoning
- Electronic navigation
- Instruments, aids, and publications
Domain 9: Q108 Navigation Problems - Near Coastal
Calculated solutions for coastal passages.
- Ocean track and Mercator sailing
- ETA, speed, RPM, and fuel calculations
- Electronic navigation, piloting, chart, and compass work
- Tide calculations
Domain 10: Q109 Navigation Problems - Oceans
The full ocean-passage problem set.
- Middle-latitude, Mercator, great-circle, and parallel sailing
- ETA, piloting, chart, and dead reckoning problems
- Celestial, Polaris, meridian, fixes, and star selection
- Times of celestial phenomena, zone time, sunrise, sunset, and twilight
- Compass azimuth and amplitude, plus tide calculations
Route Logic: Near Coastal vs. Oceans
The single most misunderstood feature of this credential is that it is not ten mandatory modules for every candidate. The two navigation general modules are alternatives. A Near Coastal route uses Q105. An Oceans route uses Q106, which adds the celestial and astronomy content. The same split applies to the problems modules: Q108 serves the Near Coastal route, while Q109 serves the Oceans route.
| Element | Near Coastal Route | Oceans Route |
|---|---|---|
| Navigation general | Q105, piloting and coastal focus | Q106, adds nautical astronomy and celestial navigation |
| Navigation problems | Q108, Mercator sailing, tides, piloting and compass calculations | Q109, adds great-circle, celestial, Polaris and twilight problems |
| Celestial work | Not required through Oceans-only content | Central to both Q106 and Q109 |
| Shared modules | Q100 through Q104 and Q107 | Q100 through Q104 and Q107 |
Key Takeaway
Do not spend weeks on celestial navigation if your approval-to-test assigns the Near Coastal route. The Near Coastal path does not require Oceans-only Q109. Read your approval-to-test first, then build your plan around the modules actually assigned to you.
What the Questions Look Like
The module titles tell you the question style. The "General" modules, Q100 through Q103 plus Q105 and Q106, lean on knowledge and judgment: rules interpretation, regulatory citations such as 33 CFR 164, seamanship decisions, and emergency procedures. The "Problems" modules, Q104, Q108, and Q109, require you to actually compute answers: a trim and stability result, a great-circle track, an ETA with fuel consumption, a celestial fix. Q107 sits in between, testing your ability to plot and solve on a chart.
This split matters for how you prepare. Knowledge modules reward careful reading and recall of rules; problem modules reward procedural fluency and accuracy under time pressure. For a candid look at where candidates struggle, see how hard the exam really is, and check what the Coast Guard considers a pass in the passing score guide. For published outcome data, the article on pass rate information explains what is and is not publicly known, so you are not misled by invented figures.
Who Hires Holders of This Endorsement
An unlimited chief mate endorsement is a working credential, not a résumé decoration. The employers that rely on it are the operators of large oceangoing and coastal tonnage:
- Deep-sea cargo and tanker operators who need qualified chief mates for unlimited-tonnage vessels
- Offshore and energy-support fleets crewing larger vessels under officer endorsements
- Government-chartered and sealift operators staffing commercial tonnage
- Cruise and passenger lines that need deck officers with passenger-safety competence, which Q103 directly addresses
- Towing and barge operators on Near Coastal routes, where the coastal navigation modules are most relevant
Pay and advancement vary widely by sector, vessel type, rotation, and union or company agreements. Rather than quoting a number that would not hold across those variables, read the salary guide for the qualitative drivers, the overview of USCG-CM-UNL jobs for role types, and the ROI analysis for how to weigh cost against career upside.
Sequencing Your Preparation by Module
This is the one place where scheduling matters, and it should follow the content, not a generic template. The logic is simple: front-load the modules that demand repeated calculation practice, and slot the memorization-heavy modules around them. A sample arrangement for a Near Coastal candidate:
Q104 and Q103 together
- Stability, trim, and damage calculations take the longest to become automatic
- Pair them with the Q103 theory so the numbers have meaning
Q105, Q107, Q108
- Chartwork, piloting, compass error, tides, and coastal problems reinforce each other
- Practice plotting daily; speed matters on Q107
Q100, Q101, Q102
- Rules of the Road, maneuvering, law, and 33 CFR 164 are recall-driven
- Review them closer to exam day so they stay fresh
An Oceans candidate would swap in Q106 and Q109 and add dedicated time for celestial work and sailings, which usually need more repetition than any other content. For a fuller plan, use the first-attempt study guide, keep the one-page review sheet nearby for final revision, and test yourself on the practice test site so weak modules surface early.
Common Misreadings to Avoid
"The exam is ten modules for everyone"
It is not. The Oceans-only content is not a universal requirement. Your approval-to-test controls what you are assigned.
"The modules have published percentage weights"
The official topic lists are unweighted. Plan by coverage and difficulty, not by invented weightings.
"Master preparation and Chief Mate preparation are the same"
The module family overlaps in places, but Master-only eligibility should not be imported into your chief mate plan. Use the chief mate topic lists.
"It is the same as another USCG-CM-UNL credential"
Several unrelated credentials share this acronym. This site covers the National Chief Mate Unlimited endorsement only. If you are researching a different credential with the same letters, its fees, dates, and domains will not match what is described here.
Frequently Asked Questions
It refers to the National Chief Mate Unlimited, Oceans or Near Coastal endorsement, examined under the United States Coast Guard National Maritime Center. For related definitions, see the pages on what the certification is and the certification overview.
No. Q105 and Q106 are route alternatives, and Q108 and Q109 follow the same split. Your USCG approval-to-test determines which modules you are assigned, so confirm that before you plan.
The official ONC01 module topics published by the NMC are unweighted. There are no official domain percentages to memorize, so prepare for full coverage of each module you are assigned.
Q104 for stability and stress, Q108 for near coastal navigation problems, and Q109 for ocean sailings and celestial solutions. Q107 also requires accurate, timed chartwork.
Scheduling is handled through the Coast Guard and its regional exam centers after approval to test. See the guide to testing windows and scheduling for how to approach planning, and verify specifics with the NMC.