- NBS here means National Barge Supervisor, a U.S. Coast Guard endorsement tied to mobile offshore drilling units (MODUs).
- The National Maritime Center administers it under examination code MODU02.
- It consists of three modules: Q100, Q437 and Q438, at 50 questions each (150 total).
- Pass marks are 90% on Q100 and 70% on both Q437 and Q438.
What NBS Means Here
Search for "NBS" and you will find a pile of unrelated credentials and organizations sharing the same three letters. This article is about exactly one of them: National Barge Supervisor. It is a maritime credential connected to the operation of mobile offshore drilling units, the floating and self-elevating rigs used in offshore energy work.
If you came looking for a different NBS, nothing here will apply to it. Everything below concerns the barge supervisor examination set administered by the U.S. Coast Guard. For the shorter definitional pages on this site, see What Does NBS Stand For? and NBS Meaning.
Who Issues the Credential
The governing body is the United States Coast Guard National Maritime Center (NMC), the office responsible for evaluating mariner credentials and administering the associated examinations. The NMC publishes an official listing for this credential under the code MODU02, which groups the Q100 and Q438 modules with Q437 as the barge supervisor examination set.
The relevant regulatory reference is the NMC Deck and Engineering Guide, which is based on regulations effective March 24, 2014. The barge supervisor material appears in the section on Mobile Offshore Drilling Unit endorsements (section 2.1.6, printed page 35). That guide is where the module structure and question counts are laid out, and it is the document to treat as the authority when a third-party summary seems to disagree with it.
For a plain-language walkthrough of what the certification represents, you can also read What Is NBS Certification? and the overview at NBS Certification.
The Three Examination Modules
The official index describes three examination modules. These are modules, not percentage-weighted content domains, and that distinction shapes how you should prepare. Nobody publishes a statement like "Module X is 30% of your score." Each module is its own test with its own pass mark.
Module 1: Q100 - Rules of the Road: International and Inland
The navigation rules module. It tests the collision-avoidance and navigation rules that govern vessel conduct, covering both international and inland waters.
- Steering and sailing rules, and how vessels must behave when meeting, crossing or overtaking
- Lights, shapes and sound signals, including how they differ between rule sets
- Responsibilities between vessels in restricted visibility and in congested waters
- The boundary between international and inland rules and where each applies
Module 2: Q437 - Barge Supervisor Deck General Safety
The deck safety module. It focuses on the practical safety knowledge needed to supervise work on deck.
- Safe deck operations and hazard recognition
- Personnel safety, protective practices and emergency awareness
- Handling of equipment and materials on a working deck
- The supervisor's role in preventing incidents, not just responding to them
Module 3: Q438 - Barge Supervisor MODU Operations
The operations module, and the one most specific to this endorsement. It addresses how mobile offshore drilling units function and how a barge supervisor fits into their operation.
- MODU types and the operational context they create
- Stability, ballast and the supervisor's responsibilities around them
- Mooring, positioning and unit movement
- Coordination with the rest of the unit's crew and command structure
A deeper treatment of each module's content is available in NBS Exam Domains 2026: Complete Guide to All 3 Content Areas.
Question Format and Passing Marks
According to the NMC Deck and Engineering Guide, each module contains 50 questions. Across the three modules, that adds up to 150 questions for the original endorsement module set. That total is a simple arithmetic sum of the module counts, not a description of one continuous test.
| Module | Subject | Questions | Passing Threshold |
|---|---|---|---|
| Q100 | Rules of the Road: International and Inland | 50 | 90% |
| Q437 | Barge Supervisor Deck General Safety | 50 | 70% |
| Q438 | Barge Supervisor MODU Operations | 50 | 70% |
Two points deserve emphasis. First, the thresholds are module pass marks, meaning you must clear each one individually. They are not content weights and they do not average together. Second, the module set is not a single timed sitting. The official sources do not assert one whole-set duration, so be skeptical of any site claiming a precise total time for "the NBS exam."
What a Barge Supervisor Actually Does
The credential only makes sense in light of the job. A barge supervisor holds responsibility for a MODU's stability and ballast-related operations, along with deck safety and the safe handling of the unit while it is moored, moving or being positioned. The position sits within the unit's command structure and requires both seamanship knowledge and an understanding of drilling-unit operations.
That combination explains the exam's design. Rules of the Road establishes that you can operate safely among other vessels. Deck General Safety establishes that you can protect people and equipment on a working deck. MODU Operations establishes that you understand the unusual vessel you are actually responsible for. Together they describe a supervisor who is a navigator, a safety lead and a rig-operations specialist at once.
Topics worth mastering early
- Right-of-way logic: know the rules cold, not roughly
- Signal recognition: lights, shapes and sound signals appear constantly on navigation-rules tests
- Stability fundamentals: how weight distribution and ballast changes affect a floating unit
- Deck hazard identification: recognizing danger before an incident, not after
- MODU vocabulary: unit types, components and operating modes
Who Hires Barge Supervisors
Demand for this endorsement comes from the offshore drilling and energy services sector. The employers are generally offshore drilling contractors and operators that run mobile offshore drilling units, along with marine service companies supporting that work. Job titles and responsibilities vary by employer and unit type, so read postings carefully rather than assuming one title always means the same duties.
For a closer look at the employment side, including how the endorsement fits into offshore career paths, read NBS Jobs. If your question is financial rather than operational, the NBS Salary Guide 2026 and Is the NBS Certification Worth It? address earnings and return on investment, and the NBS Certification Cost article covers the cost side. Note that no current fee or earnings figure is asserted here, because this article sticks to what the official sources support.
Sequencing Your Preparation
Because the three modules have different thresholds and different content, the order in which you study them matters more than any generic technique. Here is a sequence built around the actual module structure rather than a one-size-fits-all schedule.
Q100: Rules of the Road
- Start here because the 90% threshold gives you the least margin
- Drill signals, lights and shapes until recognition is instant
- Separate international and inland rules deliberately so they do not blur together
Q437: Deck General Safety
- Work through hazard scenarios and the supervisor's responsibilities in each
- Focus on understanding why procedures exist so you can reason through unfamiliar questions
Q438: MODU Operations
- Build MODU-specific knowledge last, once the navigation and safety foundations are solid
- Spend extra time on stability and ballast concepts
Mixed review
- Return to Q100 for a final pass, since it is the least forgiving module
- Take timed practice questions across all three modules
For a fuller study plan, see the NBS Study Guide 2026, and keep the NBS Cheat Sheet handy for quick review. You can also test yourself with the practice questions on the main NBS practice test site, and the NBS Training page explains how classroom and self-study routes compare.
Key Takeaway
Treat the three modules as three separate hurdles, not one blended test. Clear Q100's 90% bar first, then build outward into deck safety and MODU operations. Practice at the NBS practice test to find your weak module early.
What the Official Sources Do Not Say
Good preparation includes knowing the limits of what is publicly established. The official sources for this credential do not provide:
- Percentage weights for topics within each module
- A single, whole-set examination duration
- A current published pass rate
- A verified current fee schedule within the material this article relies on
Be cautious with any third-party claim that fills these gaps with precise figures. For topics where specifics may change, such as eligibility and scheduling, check the current official NMC pages directly. The pages on NBS Requirements, NBS Exam Dates and NBS Pass Rate explain what is and is not known, and the clarifying articles What Is A NBS? and What Does NBS Mean? cover the terminology.
The module structure described here comes from the NMC Deck and Engineering Guide (based on regulations effective March 24, 2014) and the NMC's MODU02 examination listing. This article was reviewed on October 10, 2026; that date reflects when it was checked, not a claim that the guide was revised in 2026.
Frequently Asked Questions
It stands for National Barge Supervisor, a U.S. Coast Guard maritime endorsement related to mobile offshore drilling units. It is unrelated to other credentials that share the same initials.
The United States Coast Guard National Maritime Center administers it. The official examination code is MODU02, covering modules Q100, Q437 and Q438.
Each of the three modules has 50 questions, totaling 150 across the original endorsement module set. The modules are not described as a single timed sitting.
Q100 (Rules of the Road) requires 90%, while Q437 (Deck General Safety) and Q438 (MODU Operations) each require 70%. These are per-module pass marks, not content weights.
Start with Q100, Rules of the Road. Its 90% threshold leaves the smallest margin for error, so it benefits most from early and repeated practice.