Rules of the Road
COLREGs — International Rules of the Road
The 1972 Convention on the International Regulations for Preventing Collisions at Sea. Parts A–E (Rules 1–38) are the navigation Rules tested on the USCG exam; Part F (Rules 39–41) covers verification of compliance. The Inland Navigation Rules (33 CFR Part 83) parallel them almost word-for-word, with a handful of US-specific deviations on Western Rivers and the Great Lakes.
38 navigation Rules · Parts A–EInland parallel: 33 CFR Part 83Last verified
Looking for the Inland version? See the Inland Rules directory.
Primary sources#
Checked against the current public rule corpus on .
- 33 CFR Part 83 — Inland Navigation Rules (eCFR current issue) (retrieved 4 Aug 2026 — 59 sections; last amended 6 Sept 2022)
- 33 CFR Part 80 — COLREGS Demarcation Lines (eCFR current issue) (retrieved 4 Aug 2026 — 115 sections; last amended 17 Mar 2025)
- USCG Navigation Center — International and Inland Navigation Rules (Amalgamated) (retrieved 23 May 2026)
- IMO — Convention on the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs) (retrieved 4 Aug 2026)
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. Sound-signal questions are the common trap: study COLREGs Rule 34 maneuvering and warning signals before comparing the Inland intent-signal version.
- Rule 9Inland adds descending-current right of way on Great Lakes / Western Rivers
- Rule 10Inland covers Vessel Traffic Services (VTS) instead of Traffic Separation Schemes
- Rule 24Inland adds composite-unit and Western Rivers towing-astern provisions
- Rule 34Inland signals are intent (must agree); COLREGs signals are action
- Rule 28No Inland counterpart — constrained-by-draft is COLREGs-only (Inland skips 27 → 29). See COLREGs Rule 28.
Start with the collision-avoidance sequence#
Read these five rules as a set before working through the full directory.
- Rule 5Look-out
- Rule 6Safe Speed
- Rule 7Risk of Collision
- Rule 8Action to Avoid Collision
- Rule 9Narrow Channels
Ready to test yourself? Work the free Rules of the Road practice questions — no sign-in, citation-backed against 33 CFR Part 83 and the COLREGs — or browse practice questions for every exam module.
Keep the rulebook vocabulary close as you study: review COLREGs, demarcation lines, the duties of a give-way vessel and a stand-on vessel, and the Rule 13 definition of overtaking.
All 38 COLREGs Rules by Part#
The COLREGs contain 38 navigation Rules in five Parts, A through E (Part B is subdivided into Sections I, II and III). All 38 are listed below with what each Rule covers and its Inland counterpart in 33 CFR Part 83 — 37 of the 38 have one, and only Rule 28 (vessels constrained by draft) does not. Checked against the eCFR current issue on ; Part 83 was last amended .
Part A — General
Rules 1-3: application, responsibility, definitions.
- 1ApplicationDefines the geographic scope of the rules: COLREGs applies on the high seas and connected waters; the Inland Rules apply inside the demarcation lines on US inland waters.Inland: 33 CFR §83.01
- 2ResponsibilityThe 'general prudential rule.' Nothing in the rules excuses a vessel, owner, or master from the consequences of neglect, and any rule may be departed from if necessary to avoid immediate danger.Inland: 33 CFR §83.02
- 3General DefinitionsDefines the key vocabulary used throughout the rules: 'vessel', 'power-driven vessel', 'sailing vessel', 'restricted in ability to maneuver', 'not under command', 'underway', 'restricted visibility', etc.Inland: 33 CFR §83.03
Part B-I — Conduct in Any Visibility
Rules 4-10: lookout, safe speed, risk of collision, action, narrow channels, separation schemes.
- 4ApplicationRules in Section I apply in any condition of visibility. This includes Rules 5–10 (look-out, safe speed, collision risk, avoidance action, narrow channels, traffic schemes).Inland: 33 CFR §83.04
- 5Look-outEvery vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions, so as to make a full appraisal of the situation and risk of collision.Inland: 33 CFR §83.05
- 6Safe SpeedEvery vessel shall at all times proceed at a safe speed so that proper and effective action can be taken to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.Inland: 33 CFR §83.06
- 7Risk of CollisionEvery vessel shall use all available means to determine if risk of collision exists. If there is any doubt, such risk shall be deemed to exist. Compass bearings of an approaching vessel are the canonical method.Inland: 33 CFR §83.07
- 8Action to Avoid CollisionAction to avoid collision shall be positive, made in ample time, and large enough to be readily apparent to another vessel observing visually or by radar. A succession of small alterations should be avoided.Inland: 33 CFR §83.08
- 9Narrow ChannelsA vessel proceeding along a narrow channel or fairway shall keep as near to the outer limit of the channel which lies on her starboard side as is safe and practicable.Inland: 33 CFR §83.09
- 10Traffic Separation SchemesConduct in IMO-adopted traffic separation schemes: proceed in the established direction of flow, keep clear of the separation zone or line, join or leave a lane at as small an angle as practicable.Inland: 33 CFR §83.10
Part B-II — In Sight of One Another
Rules 11-18: sailing vessels, overtaking, head-on, crossing, action by give-way / stand-on, responsibilities between vessels.
- 11ApplicationAs of 2026-07-26: the whole rule is one sentence — Rules 11 through 18 apply to vessels in sight of one another — and it is the switch that turns the give-way / stand-on system on. Everything in Section II (sailing encounters, overtaking, head-on, crossing, give-way and stand-on duties, responsibilities between vessels) exists only between vessels that can visually observe each other. Lose sight of the other vessel and you are no longer in Rule 15 or 17; you are in Rule 19, where neither vessel stands on.Inland: 33 CFR §83.11
- 12Sailing VesselsWhen two sailing vessels are approaching, the vessel with wind on her port side keeps out of the way; if both have wind on the same side, the windward vessel keeps out of the way of the leeward vessel.Inland: 33 CFR §83.12
- 13OvertakingAny vessel overtaking another shall keep out of the way of the vessel being overtaken. A vessel is overtaking when coming up from a direction more than 22.5° abaft the other's beam — i.e., she would see only the stern light at night.Inland: 33 CFR §83.13
- 14Head-on SituationWhen two power-driven vessels meet on reciprocal or nearly reciprocal courses so as to involve risk of collision, each shall alter course to starboard so that they pass on the port side of each other.Inland: 33 CFR §83.14
- 15Crossing SituationWhen two power-driven vessels are crossing so as to involve risk of collision, the vessel which has the other on her own starboard side shall keep out of the way and shall, if circumstances admit, avoid crossing ahead of the other.Inland: 33 CFR §83.15
- 16Action by Give-way VesselRule 16 is the give-way vessel rule: once another rule directs a vessel to keep out of the way, that vessel must take early and substantial action to keep well clear.Inland: 33 CFR §83.16
- 17Action by Stand-on VesselThe stand-on vessel keeps her course and speed. If it becomes apparent the give-way vessel is not taking appropriate action, the stand-on may take action; when collision cannot be avoided by the give-way alone, she shall take such action as will best aid to avoid collision.Inland: 33 CFR §83.17
- 18Responsibilities Between VesselsThe pecking order: NUC > RAM > CBD (international only) > fishing > sailing > power-driven. Each must keep out of the way of the categories above. Seaplanes and WIG craft are special cases.Inland: 33 CFR §83.18
Part B-III — Restricted Visibility
Rule 19: conduct in fog, snow, heavy rain.
Part C — Lights and Shapes
Rules 20-31: visibility, definitions, and per-vessel-type light displays.
- 20Application (Lights and Shapes)Lights are exhibited from sunset to sunrise and in restricted visibility. Shapes are exhibited by day. Annex I governs the technical particulars.Inland: 33 CFR §83.20
- 21Definitions (Lights)Rule 21 defines each navigation light by color and arc: masthead light (white, 225° forward arc), sidelights (green 112.5° starboard, red 112.5° port), sternlight (white, 135° aft), towing light (yellow, 135° aft), all-round light (360°), and flashing light (≥120 flashes per minute).Inland: 33 CFR §83.21
- 22Visibility of LightsAs of 2026-07-26: Rule 22 sets the minimum range at which each light must be visible, and the ranges depend only on the vessel's length. A vessel of 50 metres or more must show her masthead light 6 miles and her sidelights, sternlight, towing light and any all-round light 3 miles. From 12 up to 50 metres the masthead drops to 5 miles — but only 3 miles if the vessel is under 20 metres — and everything else to 2 miles. Under 12 metres the masthead is 2 miles, the sidelights just 1 mile, and the sternlight, towing light and all-round lights 2 miles. An inconspicuous, partly submerged vessel or object shows a white all-round light visible 3 miles.Inland: 33 CFR §83.22
- 23Power-driven Vessel UnderwayAs of 2026-08-10: a power-driven vessel underway shows a masthead light forward, a second masthead light abaft of and higher than the forward one, sidelights and a sternlight. The second masthead light is optional below 50 metres, which is why most vessels a six-pack operator meets carry one masthead light, not two. Below 12 metres she may instead show an all-round white light and sidelights, and under the International Rules only, a vessel under 7 metres that cannot exceed 7 knots may show the all-round white light alone. An air-cushion vessel operating in non-displacement mode adds an all-round flashing yellow light, and a WIG craft taking off, landing or flying near the surface adds a high-intensity all-round flashing red.Inland: 33 CFR §83.23
- 24Towing and PushingAs of 2026-06-25, Rule 24 is the towing-lights rule: towing astern uses two masthead lights, but a tow over 200 m requires three masthead lights and a diamond; pushing ahead or towing alongside uses a different two-towing-light pattern, with a special Inland Western Rivers exception.Inland: 33 CFR §83.24
- 25Sailing Vessels Underway and Vessels Under OarsAs of 2026-07-26: a sailing vessel underway shows sidelights and a sternlight — and nothing else that is mandatory. Under 20 metres those may be combined in one lantern at or near the top of the mast. She may optionally add two all-round lights in a vertical line at the masthead, red over green. Under 7 metres, if the prescribed lights are impracticable, it is enough to have an electric torch or lighted lantern showing a white light ready at hand, exhibited in time to prevent collision. A vessel under oars may use the sailing-vessel lights or fall back on the same white light.Inland: 33 CFR §83.25
- 26Fishing VesselsAs of 2026-07-26: the rule splits fishing into two light pictures. A vessel TRAWLING — dragging a dredge or other apparatus through the water — shows two all-round lights in a vertical line, green over white, plus sidelights and a sternlight when making way. Any OTHER vessel engaged in fishing shows two all-round lights in a vertical line, red over white, and when her outlying gear extends more than 150 metres horizontally, an additional all-round white light (or a cone apex upwards by day) in the direction of the gear. A vessel not engaged in fishing shows only the lights for a vessel of her length.Inland: 33 CFR §83.26
- 27Vessels Not Under Command or Restricted in Their Ability to ManeuverAs of 2026-08-09: two different conditions with two different light signatures. A vessel NOT UNDER COMMAND — unable to manoeuvre through some exceptional circumstance — shows two all-round red lights in a vertical line, and two balls by day. A vessel RESTRICTED IN HER ABILITY TO MANOEUVRE — able to steer but constrained by the work she is doing — shows red-white-red in a vertical line, and ball-diamond-ball by day, with one exception: a vessel engaged in mine clearance is expressly carved out of that signal and shows three all-round green lights or three balls instead. Either adds sidelights and a sternlight when making way, and the restricted vessel adds masthead lights when underway. Dredging and underwater operations extend the restricted signal with two red lights or balls on the obstructed side and two green lights or diamonds on the side a vessel may pass.Inland: 33 CFR §83.27
- 28Vessels Constrained by Their DraftA power-driven vessel constrained by her draft may exhibit three all-round red lights in a vertical line, or by day a cylinder.Inland: no counterpart
- 29Pilot VesselsOn pilotage duty: white-over-red all-round at masthead + sidelights and sternlight when underway, or anchor light(s) when at anchor. When not on pilotage duty, exhibits the lights of a similar-length ordinary vessel.Inland: 33 CFR §83.29
- 30Anchored Vessels and Vessels AgroundAt anchor: forward all-round white (and a second all-round aft if 50 m+), or one ball by day. Aground: same as anchored plus two all-round red, or three balls by day.Inland: 33 CFR §83.30
- 31SeaplanesSeaplanes (and WIG craft) exhibit lights and shapes characteristic of vessels of their category as far as practicable.Inland: 33 CFR §83.31
Part D — Sound and Light Signals
Rules 32-37: equipment, maneuvering, restricted-visibility, distress signals.
- 32Sound Signal DefinitionsDefines whistle, short blast (≈1 sec), and prolonged blast (4–6 sec). 'Whistle' includes any sound-signalling appliance capable of producing the prescribed blasts.Inland: 33 CFR §83.32
- 33Equipment for Sound Signals12 m+: whistle. 20 m+: whistle + bell. 100 m+: whistle + bell + gong (gong of different tone from bell). Smaller vessels are not obliged to carry these but must have some efficient sound signal.Inland: 33 CFR §83.33
- 34Maneuvering and Warning SignalsThe sound signals for manoeuvring, overtaking, blind bends, and doubt — and the one rule where International and Inland disagree on what a blast means: an action already taken, or an intention the other vessel must answer.Inland: 33 CFR §83.34
- 35Sound Signals in Restricted VisibilityPower-driven making way: 1 prolonged every ≤2 min. Power-driven underway but stopped: 2 prolonged every ≤2 min. NUC, RAM, CBD, sailing, fishing, towing: 1 prolonged + 2 short every ≤2 min. At anchor: bell rung rapidly for 5 sec every ≤1 min (50 m+ adds gong aft).Inland: 33 CFR §83.35
- 36Signals to Attract AttentionAny vessel may, if necessary to attract another's attention, make light or sound signals that cannot be mistaken for a signal authorized elsewhere in the rules, or direct the beam of her searchlight in danger's direction (without embarrassing other vessels).Inland: 33 CFR §83.36
- 37Distress SignalsAnnex IV lists the distress signals: SOS, MAYDAY voice, NC flag hoist, square-flag-and-ball, continuous fog horn, gun fired at one-minute intervals, red star rockets, parachute red flare, hand red flare, orange smoke, slow-and-repeated arm raise/lower, EPIRB, DSC alert.Inland: 33 CFR §83.37
Part E — Exemptions
Rule 38: phase-in exemptions for rule changes.
Frequently asked#
How many COLREGs rules are there?
38 navigation Rules (Parts A–E) grouped into five parts (A through E), plus four annexes covering technical light, shape, and equipment specs. (The full convention has 41 Rules in six Parts; Part F, Rules 39–41, added in 2016, covers verification of compliance and is not a navigation rule or tested.) The US Inland Navigation Rules in 33 CFR Part 83 carry 37 rules — Inland skips Rule 28 (constrained by draft).
What are the Parts of the COLREGs, and which Rules are in each?
Five Parts, A through E. Part A — General is Rules 1-3 (application, responsibility, definitions). Part B — Steering and Sailing is Rules 4-19 and is the only Part divided into Sections: Section I, conduct in any visibility (Rules 4-10); Section II, conduct in sight of one another (Rules 11-18); Section III, conduct in restricted visibility (Rule 19). Part C — Lights and Shapes is Rules 20-31. Part D — Sound and Light Signals is Rules 32-37. Part E — Exemptions is Rule 38. Four annexes follow the Rules and carry the technical specifications for lights, shapes, sound signals, and distress signals.
Where can I read the full text of every COLREGs rule?
The rule text is public domain. The US Inland text sits in 33 CFR Part 83 on eCFR — 59 sections, last amended 6 Sept 2022 and still the current issue as of 4 Aug 2026. The USCG Navigation Center publishes the Amalgamated International & Inland Navigation Rules, which prints the COLREGs and Inland text side by side, and the IMO holds the convention itself. The directory on this page lists all 38 Rules with what each one covers and its Inland section number, and each links through to a summary with exam-frequency notes.
What does COLREGs stand for?
The 1972 Convention on the International Regulations for Preventing Collisions at Sea. The acronym is sometimes written COLREGS or COLREG; all refer to the same IMO treaty.
Where do COLREGs apply versus the Inland Rules?
COLREGs apply on the high seas and all connected navigable waters outside the COLREGS demarcation lines fixed by 33 CFR Part 80. Inside those lines — most US harbors, bays, and Western Rivers — 33 CFR Part 83 (the Inland Navigation Rules) controls. The same vessel can be subject to both rule sets on a single transit.
Which COLREGs rules show up most on the USCG license exam?
Rules 5-9 (lookout, safe speed, risk of collision, action to avoid, narrow channels) anchor the collision-avoidance sequence. Rules 13-15 (overtaking, head-on, crossing) and Rule 18 (responsibilities between vessels) drive most situation questions. Rules 23-30 (lights and shapes) and Rule 34 (maneuvering and warning sound signals) carry the highest single-rule question density on the Rules of the Road module.
Are COLREGs and the Inland Rules really the same?
Mostly. The Inland Rules mirror COLREGs almost verbatim with five exam-relevant divergences (Rules 9, 10, 24, 28, and 34) plus Western-Rivers and Great-Lakes-specific provisions. The /vs/inland-vs-international-rules page lists each line-by-line difference.
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