- What You're Actually Studying For
- How the Exam Is Built: Modules, Not a Single Test
- Rules of the Road: The Module You Cannot Fake
- Deck General and Deck Safety: The Working Mariner's Knowledge
- Navigation General and Navigation Problems
- Towing Vessel Operations: Where Your Endorsement Lives
- Sequencing Your Prep Around the Six Domains
- Paperwork, Sea Service, and Scheduling Mechanics
- Where First-Attempt Candidates Come Unglued
- Who Hires Apprentice Mates (Steersmen)
- Frequently Asked Questions
- This credential is the National Apprentice Mate (Steersman) of towing vessels, governed by the Coast Guard's National Maritime Center.
- Testing is organized by official NMC modules: Rules of the Road, Deck General, Deck Safety, Navigation General, and navigation problems.
- Rules of the Road is the module to master first, since it underpins both navigation and towing operations.
- Navigation problems reward worked practice with plotting and calculations, not memorized facts.
What You're Actually Studying For
The credential covered here is the National Apprentice Mate (Steersman) OC, NC, GL-IN, WR, a Coast Guard endorsement for people who want to stand watch and steer on towing vessels while working toward a mate's role. The endorsement scopes in the title (oceans, near-coastal, Great Lakes and inland, western rivers) describe where the holder may operate. Note that "USCG-AMS" on this site refers only to this mariner credential. Other certifications share the acronym, and none of their rules or requirements apply here.
The issuing authority is the United States Coast Guard National Maritime Center (NMC). That matters for your preparation, because the NMC publishes examination modules and topic outlines, and your study plan should follow those source documents rather than a generic "maritime exam" outline. If you are brand new to the credential, start with What Is USCG-AMS? and then return here for the preparation plan.
This guide assumes you already know why you want the endorsement and focuses on how to prepare. For a candid read on difficulty before you commit months of effort, see How Hard Is the USCG-AMS Exam?.
How the Exam Is Built: Modules, Not a Single Test
Coast Guard deck licensing exams are organized into discrete modules, each covering a body of knowledge. The NMC examination module sources identify modules including Rules of the Road, Deck General, Deck Safety, Navigation General, and navigation problem modules. For this article we group your preparation into six domains:
| Domain | What It Tests | Type of Skill |
|---|---|---|
| Navigation Rules | Collision-avoidance rules, lights, shapes, sound signals, right-of-way | Recall plus scenario application |
| Deck General | Seamanship, vessel handling, equipment and general deck knowledge | Applied knowledge |
| Deck Safety | Safety practices, emergency procedures, lifesaving and firefighting basics | Procedural recall |
| Navigation General | Charts, aids to navigation, compasses, publications, tides and currents | Interpretation |
| Navigation Problems | Plotting and calculation exercises | Worked computation |
| Towing Vessel Operations | Operations specific to towing vessels and the work of an apprentice mate | Applied, role-specific |
Rules of the Road: The Module You Cannot Fake
If one subject deserves your earliest and most sustained attention, it is the Navigation Rules domain. It is the foundation for everything a steersman does on the bridge, and the vocabulary and logic show up again in navigation problems and in towing operations.
Domain 1: Navigation Rules
Candidates must apply the rules to situations, not just recite them. The questions are built around what a vessel should do, what a light or shape display indicates, and which vessel holds the privilege.
- Know the steering and sailing rules cold: give-way versus stand-on roles, and the conduct required in each situation (overtaking, crossing, head-on).
- Learn lights and shapes by vessel type, including the displays specific to vessels engaged in towing, which carry extra masthead lights and a distinctive towing light arrangement.
- Memorize sound and light signals, including maneuvering and warning signals and signals used in restricted visibility.
- Understand how rules differ by waters. Inland rules and international rules are not identical, and your endorsement scope determines how much of each you should expect to be tested on.
Practical advice: do not learn light displays as a flat list. Build the habit of describing what an approaching vessel is doing from the lights alone (underway or at anchor, towing or not, length of tow, constrained or not). That scenario-based reading is exactly how exam questions are framed.
Deck General and Deck Safety: The Working Mariner's Knowledge
These two domains test whether you understand the vessel and the deck environment well enough to work safely. They are less glamorous than navigation but they are where experienced deckhands often outperform classroom-only candidates, and where classroom-only candidates often lose points.
Domain 2: Deck General
Expect questions rooted in seamanship and the practical operation of a deck department.
- Vessel terminology, construction and stability fundamentals as they apply to towing vessels.
- Mooring, anchoring and line handling, including the safe working practices around wire and synthetic line.
- Deck equipment knowledge such as winches, rigging and the gear used in towing and barge work.
- Weather awareness and its effect on vessel handling.
Domain 3: Deck Safety
Safety questions typically ask for the correct response, the correct procedure, or the correct equipment for a described situation.
- Emergency response fundamentals: fire, flooding, collision, grounding and person overboard.
- Lifesaving appliances and firefighting equipment, including what each is for and when it is used.
- Pollution prevention and required responses to spills.
- Safe work practices on deck, including personal protective equipment and hazard awareness around tows.
Navigation General and Navigation Problems
These two domains are related but demand different study methods. Navigation General is a knowledge domain. Navigation Problems is a skills domain. Treating them the same is a common mistake.
Navigation General
Domain 4: Navigation General
This domain covers the tools and information a mariner uses to know where the vessel is and where it can safely go.
- Chart reading: symbols, abbreviations, soundings, datums and chart notes.
- Aids to navigation: buoyage systems, lights, daybeacons and the logic of lateral marking.
- Compass use, including variation and deviation concepts.
- Government publications a mariner is expected to know, such as light lists and coast pilots, and what each contains.
- Tides and currents and their practical effect on a vessel's track.
Navigation Problems
Domain 5: Navigation Problems
Navigation problems are worked exercises. You are given a set of conditions and must plot or calculate a result accurately.
- Plotting position, courses and bearings on a chart or plotting sheet.
- Applying compass corrections to convert between true, magnetic and compass courses.
- Time, speed and distance calculations.
- Current and set-and-drift problems affecting the course to steer.
You cannot cram your way through plotting. The only reliable approach is to work a large number of problems by hand, check them against answers, and diagnose every error. Make a short log of the mistakes you repeat, whether that is a sign error on a compass correction or a misread scale. Most of your remaining errors will cluster into two or three habits.
Key Takeaway
Treat Navigation General as a reading-and-recall domain and Navigation Problems as a repetition-and-accuracy domain. Practice test questions help the first; physical plotting practice is the only real preparation for the second.
Towing Vessel Operations: Where Your Endorsement Lives
What distinguishes this credential from a generic deck licensing path is the towing context. An apprentice mate (steersman) of towing vessels is being prepared to stand watch on a vessel pushing or pulling barges, and the knowledge base reflects that.
Domain 6: Towing Vessel Operations
Expect your study here to tie together rules, deck practice and navigation as they apply to a tow.
- Towing arrangements and terminology: pushing, towing alongside, towing astern, and the gear and rigging associated with each.
- Handling a vessel with a tow, including the effect of the tow on maneuverability and stopping distance.
- Lights and signals specific to towing operations, tying back to the Navigation Rules domain.
- Lock, bridge and restricted-waterway considerations relevant to your route and endorsement scope.
- The responsibilities and limits of an apprentice mate working under a licensed master or mate.
Because the endorsement title lists several operating areas (oceans, near-coastal, Great Lakes and inland, western rivers), the emphasis you place within this domain should reflect your intended route. A river towboat deckhand and a coastal tug deckhand will have different day-to-day familiarity, and you should deliberately shore up whichever areas your background has not covered. See USCG-AMS requirements for how route and sea service interact.
Sequencing Your Prep Around the Six Domains
Generic study techniques only help once they are pinned to this credential's content. Here is a domain-driven sequence that front-loads the foundational material and leaves the skill-heavy material for sustained repetition.
Navigation Rules First
- Learn steering and sailing rules and the lights, shapes and signals for each vessel type.
- Do daily scenario drills describing what an approaching vessel is doing from its lights.
- Reason: nearly every later domain assumes you can read the rules fluently.
Deck General and Deck Safety
- Link each topic to a real task or a conversation with a working deckhand or mate.
- Review emergency procedures and equipment until you can state them without prompting.
Navigation General, Then Problems
- Spend the first week on chart symbols, aids to navigation, publications, tides and currents.
- Spend the remaining weeks working navigation problems by hand every study session, logging repeat errors.
Towing Operations and Full Review
- Integrate towing-specific lights, arrangements and handling with the rules and navigation work.
- Take timed practice sets across all six domains and revisit the weakest one.
If you have significant deck experience you can compress the middle weeks, and if you are new to the water you should stretch them. The point is the order: rules, then deck knowledge, then navigation skills, then integration. For a compact reference to keep beside your notes, the USCG-AMS cheat sheet distills the must-know facts.
Paperwork, Sea Service, and Scheduling Mechanics
Mariner credentials differ from many certifications because the exam is only one piece of an application. The Coast Guard evaluates your eligibility through the National Maritime Center, and examination is tied to that evaluation.
- Sea-service prerequisites depend on your route and endorsement path. Confirm the documented time and type of service you need for your intended scope before investing in preparation.
- The NMC is the governing body. Use its published guidance and module information as your source of truth rather than third-party summaries.
- Fees and scheduling are handled through the Coast Guard evaluation and examination process. Exact current fees and dates should be verified directly with the NMC, since they can change. For planning context, see our breakdowns of certification cost and exam dates and scheduling.
Questions about what counts as a passing performance are covered in USCG-AMS passing score, and the data discussion lives in USCG-AMS pass rate. We do not quote numbers there that cannot be verified, and you should be skeptical of any source that does.
Where First-Attempt Candidates Come Unglued
Because this is a module-based credential, failure usually looks like one weak domain dragging down an otherwise strong candidate. The patterns below are the ones worth guarding against.
- Underestimating Navigation Rules. Candidates who have worked on deck for years sometimes assume the rules are common sense. The exam asks about specific lights, shapes and signals, and gut instinct does not substitute for the exact answer.
- Skipping hands-on plotting practice. Reading about navigation problems is not the same as working them. Candidates who only review solutions tend to stumble when they have to produce one.
- Neglecting the domain outside your daily work. A deckhand strong on Deck General may be weak on chart work, and a classroom student may be the reverse. Study your gaps, not your strengths.
- Ignoring route scope. If your endorsement covers inland or western rivers, make sure you know how those waters' rules and operating conditions differ from coastal ones.
- Waiting too long to take timed practice. Working problems untimed in week two is fine; arriving at test day never having worked under time pressure is not.
Key Takeaway
Diagnose by domain, not by overall confidence. After every practice session, record which of the six domains produced your misses, and let that record, not your mood, decide what you study next. You can find domain-organized questions in our practice tests.
Who Hires Apprentice Mates (Steersmen)
The employers for this endorsement are the operators of towing vessels. That includes inland towboat companies moving barges on rivers and waterways, coastal and harbor tug and barge operators, and companies working on the Great Lakes. Many of these employers use the apprentice mate path to develop deckhands into licensed officers, which is part of why experienced deck crew often target this credential.
For a closer look at the employment landscape, read USCG-AMS jobs. If you are weighing the investment of time and money, Is the USCG-AMS certification worth it? and the salary guide cover the return question without relying on invented figures.
Frequently Asked Questions
It is the National Apprentice Mate (Steersman) endorsement for towing vessels, issued by the Coast Guard's National Maritime Center. The OC, NC, GL-IN, and WR designations describe the operating areas covered: oceans, near-coastal, Great Lakes and inland, and western rivers. Your specific scope depends on the route and endorsement path you qualify for.
Start with Navigation Rules. It underpins the rest of the material, including towing-specific lights and signals, and its scenario-based questions reward early, repeated practice. Navigation Problems should get steady hands-on repetition throughout rather than a last-minute push.
Official percentage weights for these topic headings were not verified, so we do not publish them. Prepare for every module as though it must be passed on its own, and use the NMC's published module information for the authoritative breakdown.
Sea-service prerequisites depend on your route and endorsement path, and your application is evaluated through the National Maritime Center. Confirm your eligibility with the NMC before building your study timeline. Our requirements guide explains the general framework.
Look for consistent performance across all six domains rather than a high average that hides a weak spot. Work timed practice sets, log your errors by domain, and make sure your plotting is accurate without relying on answer keys. The USCG-AMS study guide and the practice test site give you material for that self-check.