The 10 Most Commonly Missed USCG Rules of the Road Questions

Most USCG Rules of the Road exam failures come from the same patterns. Candidates know the common material — give-way, stand-on, Rule 15 crossing — but these ten topics have specific traps built into the question format that produce wrong answers at a high rate. Reading them once is not enough. Drilling them until the trap no longer fires is the goal.

1. The Overtaking-at-Night Trap

The scenario: You are approaching a vessel from astern in darkness. You can see her sternlight only — no sidelights visible. Is this an overtaking situation?

Why candidates miss it: Candidates read "I can't see the sidelights" and think the overtaking classification requires visual confirmation of the 22.5-degree geometry. It does not.

The correct answer: Yes, this is an overtaking situation. Rule 13(b) defines the overtaking zone as "more than 22.5 degrees abaft the beam." Rule 13(b) then confirms: "If at night she could see only the sternlight and neither of the sidelights of such vessel, she shall be deemed to be overtaking vessel." The ability to see only the sternlight is itself the confirmation. Rule 13(d) adds that when in any doubt, the vessel must assume she is overtaking and act accordingly. Overtaking vessel keeps clear under Rule 13(a).

2. Three Blasts Does Not Mean "Going Astern"

The scenario: You hear three short blasts from a vessel in your vicinity. What does this signal mean?

Why candidates miss it: The exam question and the intuitive answer both point toward "the vessel is moving astern." Three blasts is commonly described shorthand as "going astern" in study materials, and candidates stop there.

The correct answer: Rule 34(a) states that three short blasts means "I am operating astern propulsion." This means the engines are going astern — it says nothing about the direction the vessel is moving. A vessel that has been proceeding ahead and rings up full astern on the engine order telegraph gives three short blasts. She is still moving forward through the water on momentum while her engines work astern. The signal describes propulsion direction, not vessel movement. The exam exploits this distinction with questions that require you to say whether the vessel is moving astern — and the correct answer is that you cannot determine that from three blasts alone.

3. The Fishing Vessel vs. Trawler Lights Swap

The scenario: You see a green all-round light over a white all-round light. What type of vessel is this?

Why candidates miss it: Fishing vessel lights are one of the most tested topics, and "red over white" is so well-drilled that candidates sometimes invert the colors when a different color appears.

The correct answer: Green over white all-round lights identify a vessel engaged in trawling under Rule 26(b). A vessel engaged in fishing other than trawling shows red over white all-round lights under Rule 26(b) as well. The distinction is the gear type: trawling means actively dragging fishing gear through the water (trawl, purse seine). If you see green over white, you are looking at a trawler. Red over white is a vessel fishing but not trawling. Both also show sidelights and sternlights when making way. Green = trawler. Red = fishing (non-trawling). These are among the most frequently swapped lights on the written exam.

4. NUC Vessels Do Not Show Masthead Lights

The scenario: A vessel not under command is making way. What lights does she show?

Why candidates miss it: Candidates learn the general principle that power-driven vessels making way show two masthead lights, sidelights, and a sternlight — and apply that framework to every vessel making way, including NUC vessels.

The correct answer: Rule 27(a) specifies that a vessel not under command shall exhibit two all-round red lights in a vertical line. Rule 27(a)(ii) adds sidelights and a sternlight when making way. Masthead lights are never shown. The masthead light is a characteristic of a power-driven vessel under command and proceeding normally. NUC status explicitly means the vessel cannot maneuver as required by the rules — showing masthead lights would make her look like a normal underway vessel. Two all-round reds is the distinguishing signal. On the exam, any answer choice that adds a masthead light to a NUC vessel is wrong.

5. Rule 19 Governs Restricted Visibility — Not Rule 16 or Rule 17

The scenario: You are in restricted visibility and hear a prolonged blast repeated approximately every two minutes forward of your beam. You cannot determine that risk of collision does not exist. What do you do?

Why candidates miss it: Rules 16 and 17 are the core of most exam prep — give-way vessel keeps clear, stand-on vessel maintains. Candidates reflexively apply this framework to any collision-avoidance question, including fog.

The correct answer: Rule 19 applies when vessels are not in sight of each other — which is always the case in restricted visibility by definition. Rules 16 and 17 (give-way and stand-on obligations) apply only between vessels that are in sight. In restricted visibility, there is no give-way vessel and no stand-on vessel. Instead, Rule 19(d) requires: if a vessel hears a fog signal forward of her beam and cannot determine that risk of collision does not exist, she shall reduce speed to the minimum at which she can be kept on course. Rule 19(d)(ii) requires that if a vessel detects by radar a vessel forward of her beam, she shall take avoiding action in ample time. Rule 19(e) prohibits altering course to port for a vessel forward of the beam unless overtaking. The action is reduction to minimum steerage speed — not give-way logic.

6. Constrained by Draft Signals Exist in COLREGS Only, Not Inland

The scenario: A deep-draft vessel is navigating in a channel in inland waters. What special lights or shapes does she display?

Why candidates miss it: Rule 28 (Constrained by Draft) defines a specific signal: three all-round red lights in a vertical line, or a cylinder dayshape. Candidates study this rule and apply it to any deep-draft vessel question.

The correct answer: Rule 28 exists in the International Regulations for Preventing Collisions at Sea (72 COLREGS) — it has no equivalent in the U.S. Inland Navigation Rules. A vessel constrained by her draft on the high seas may exhibit the three red lights and cylinder. A vessel in the same condition in inland waters has no special signals to display. She must navigate with care and sound seamanship, but she shows no distinguishing signal. The exam tests this as a direct comparison: Inland vs. International. The answer to "what signals does a CBD vessel display in inland waters" is: none that are specific to her draft situation.

7. Inland Rule 34 Signals Indicate Intent, Not Action

The scenario: Under Inland Rules, you sound one short blast and the other vessel answers with one short blast. What has been agreed?

Why candidates miss it: Under International COLREGS, Rule 34 signals are action signals. One short blast means "I am altering my course to starboard" — describing what the vessel is doing. Candidates who study both rulesets sometimes apply the COLREGS interpretation to an Inland question.

The correct answer: Under the Inland Navigation Rules, Rule 34 signals are intent signals and they require agreement. One short blast from the initiating vessel means "I intend to leave you on my port side" (pass port-to-port). The receiving vessel answers one short blast to indicate agreement. If the receiving vessel disagrees or is in doubt, she sounds the danger signal (five or more short blasts). No one alters course until agreement is established. The exam tests this with questions that ask what the signal "means" in inland waters versus international waters, or questions about what a vessel must do after sounding one blast. In COLREGS, she acts. In Inland, she waits for the response.

8. A Motor-Sailing Vessel Is a Power-Driven Vessel

The scenario: A sailing vessel is under sail and engine simultaneously. What lights must she display?

Why candidates miss it: Candidates know that sailing vessels show sidelights and a sternlight, plus optionally a red-over-green all-round light combination at the masthead for sailing vessels under 20 meters. They apply the sailing vessel rules.

The correct answer: Rule 25(e) states that a vessel proceeding under sail when also being propelled by machinery shall exhibit forward, where it can best be seen, a conical shape apex downwards. She is treated as a power-driven vessel for rules purposes. She displays masthead lights, sidelights, and a sternlight — the power-driven vessel light configuration — plus the black cone as a dayshape during daylight hours. The optional all-round red-over-green sailing vessel light is not displayed while motoring. The cone is required, not optional. Missing the cone is the most common single-vessel lights error on the exam for this vessel type.

9. A Channel-Crossing Vessel Faces Rule 9, Not Rule 15

The scenario: You are crossing a narrow channel. A power-driven vessel is proceeding along the channel and cannot navigate safely outside it. The channel vessel is to your starboard. Are you the give-way vessel under Rule 15?

Why candidates miss it: When two power-driven vessels are involved and one is to starboard, candidates apply Rule 15. It feels like a crossing situation.

The correct answer: Rule 9(d) applies. A vessel shall not cross a narrow channel or fairway if such crossing impedes the passage of a vessel that can only safely navigate within the channel. The obligation is not "give-way" under Rule 15 — it is "shall not impede." The distinction matters because "shall not impede" means the crossing vessel must not create a situation where the channel vessel is forced to alter course or slow. The crossing vessel must wait, slow, or abort the crossing entirely rather than simply passing behind the channel vessel. Rule 15 still exists on the other side of the channel once you are in open water — but in the channel, Rule 9 controls. The vessel's position relative to your starboard or port is irrelevant under Rule 9. The obligation falls on the crossing vessel categorically.

10. Rule 2 — The Rules End Where Seamanship Begins

The scenario: Following the applicable rule would place your vessel in immediate danger of collision. What governs?

Why candidates miss it: This question is philosophical in a way that exam prep rarely addresses. Candidates who have drilled rule application stop at the specific rule without knowing about Rule 2's override authority.

The correct answer: Rule 2(b) states: "In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may render a departure from these Rules necessary to avoid immediate danger." Rule 2 is the escape valve. No rule requires a mariner to follow the rules into a wreck. If compliance with a specific rule would produce an immediate collision that a departure from the rules could avoid, the departure is required. The rules exist to prevent collisions. A rule that would cause a collision in a specific circumstance cannot be what the rule intends. Rule 2 appears on exams as a conceptual question about the nature of the rules — the answer is that they have limits, and seamanship judgment is always the overriding obligation.

Drilling these ten patterns until the trap does not fire is more effective than one reading pass. The failure mode in each case is a confident wrong answer — the candidate knows something, applies it, and gets the question wrong because they applied the slightly wrong version. Free practice at Binnacle School runs questions in these categories so you can confirm the correct logic under exam conditions before your appointment.