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Inland Navigation Rules

The US Inland Navigation Rules — 33 CFR Part 83, 37 rules across five parts. They mirror the international COLREGs almost verbatim with a handful of structural deviations: Inland Rule 10 covers Vessel Traffic Services rather than Traffic Separation Schemes, there is no Inland Rule 28 (constrained-by-draft is COLREGs-only), and Western-Rivers and Great-Lakes traffic gets descending-current right of way under several rules.

Studying for the Near-Coastal endorsement? See the international COLREGs directory →

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Where Inland diverges from COLREGs

Five rules carry exam-relevant differences. Read each pair together — see the full side-by-side comparison for the rest.

Start with the collision-avoidance sequence

Read these five rules as a set before working through the full directory.

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Part A — General

Rules 1-3: application (and the 33 CFR Part 80 demarcation lines that fix where Inland applies), responsibility, definitions.

Part B-I — Conduct in Any Visibility

Rules 4-10: lookout, safe speed, risk of collision, action to avoid, narrow channels, and Vessel Traffic Services — Inland Rule 10 is VTS, not Traffic Separation Schemes.

Part B-II — In Sight of One Another

Rules 11-18: sailing vessels, overtaking, head-on, crossing, give-way / stand-on action, responsibilities between vessels.

Part B-III — Restricted Visibility

Rule 19: conduct in fog, snow, heavy rain.

Part C — Lights and Shapes

Rules 20-31, skipping Rule 28 (constrained-by-draft is COLREGs-only): visibility, definitions, and per-vessel-type light and shape displays.

Part D — Sound and Light Signals

Rules 32-37: equipment, maneuvering signals of intent, restricted-visibility fog signals, distress signals.

Part E — Exemptions

Rule 38: phase-in exemptions for rule changes.

Frequently asked

How many Inland Navigation Rules are there?

37 numbered rules in 33 CFR Part 83, grouped into five parts (A through E). Inland carries one fewer than the 38 international COLREGs rules because there is no Inland Rule 28 — 'constrained by draft' is COLREGs-only, so the Inland numbering jumps straight from Rule 27 to Rule 29.

What CFR are the Inland Navigation Rules in?

33 CFR Part 83. The technical annexes — light positioning, sound-signal appliances, distress signals, and pilot rules — are in 33 CFR Parts 84-88, and the COLREGS demarcation lines that fix where the Inland Rules take over from the international rules are in 33 CFR Part 80.

Where do the Inland Navigation Rules apply?

Shoreward of the COLREGS demarcation lines fixed by 33 CFR Part 80 — most US harbors, bays, rivers, the Great Lakes, and Western Rivers. Outside those lines, on the high seas and connected coastal waters, the international COLREGs control. A single coastal transit can cross between the two rule sets.

How is Inland Rule 34 different from COLREGs Rule 34?

Under the Inland Rules, maneuvering whistle signals are signals of intent that must be answered and agreed before either vessel acts: one short blast means 'I intend to leave you on my port side', two short blasts means 'on my starboard side'. Under COLREGs the identical signals describe action already being taken ('I am altering my course to starboard'). This intent-versus-action distinction is one of the most-tested Rules of the Road exam points.

Are the Inland Rules and COLREGs the same?

They mirror each other almost word-for-word, with five exam-relevant divergences — Rules 9, 10, 24, 28, and 34 — plus Western-Rivers and Great-Lakes provisions. The /vs/inland-vs-international-rules page lists each line-by-line difference.

Inland Navigation Rules — All 37 US Rules (33 CFR Part 83) · CaptainsGround