# ColRegs — Rules of the Road

International Regulations for Preventing Collisions at Sea (COLREGS), 1972 with amendments. This is a summary reference; consult the official text for legal purposes.

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## Part A — General (Rules 1–3)

**Rule 1 — Application**
Applies to all vessels on the high seas and connected navigable waters.

**Rule 2 — Responsibility**
Nothing in these rules exonerates a vessel, owner, master, or crew from the consequences of neglect. Good seamanship always applies.

**Rule 3 — Definitions**
- *Vessel* — any watercraft, including seaplanes and WIG craft
- *Power-driven vessel* — any vessel propelled by machinery
- *Sailing vessel* — under sail only; if engine is running, she is power-driven
- *Vessel engaged in fishing* — using nets, lines, trawls that restrict maneuverability
- *Underway* — not at anchor, aground, or made fast to shore
- *Restricted visibility* — fog, mist, falling snow, heavy rain, sandstorm, or similar conditions

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## Part B — Steering and Sailing Rules

### Section I — Conduct in Any Visibility (Rules 4–10)

**Rule 4** — Applies in any condition of visibility.

**Rule 5 — Look-out**
Every vessel shall maintain a proper look-out at all times by sight, hearing, and all available means.

**Rule 6 — Safe Speed**
Every vessel shall proceed at a safe speed. Factors: visibility, traffic density, vessel maneuverability, background lights at night, radar state, sea state.

**Rule 7 — Risk of Collision**
Risk exists if the compass bearing of an approaching vessel does not appreciably change. When in doubt, assume risk exists.

**Rule 8 — Action to Avoid Collision**
- Action must be positive, made in ample time, and large enough to be readily apparent
- Course or speed changes should be large enough to be noticed
- If necessary, stop or reverse

**Rule 9 — Narrow Channels**
- Keep to the starboard side of a narrow channel
- Vessels under 20 m or sailing vessels shall not impede vessels that can safely navigate only in the channel
- Overtaking only when safe and the overtaken vessel signals agreement
- Do not cross a narrow channel if it impedes a through-traffic vessel

**Rule 10 — Traffic Separation Schemes**
- Join/leave at end; if joining from side, at acute angle
- Keep out of separation zones
- Crossing traffic does so at right angles where practicable
- Inshore traffic zones: use only if < 20 m, or sailing, or fishing

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### Section II — Conduct in Sight of One Another (Rules 11–18)

**Rule 11** — Applies to vessels in sight of one another.

**Rule 12 — Sailing Vessels**
- Vessel on port tack gives way to vessel on starboard tack
- Both on same tack: windward vessel gives way to leeward vessel
- Port tack vessel cannot determine which tack the other is on: gives way

**Rule 13 — Overtaking**
Any vessel overtaking gives way. Overtaking means coming up from more than 22.5° abaft the other's beam. Overtaking status persists until clear and past.

**Rule 14 — Head-on Situation**
Both vessels altering course to starboard so each passes on the port side of the other. Applies when risk of collision exists and vessels are nearly end-on.

**Rule 15 — Crossing Situation**
The vessel that has the other on its own starboard side gives way (the "burdened" or give-way vessel). The stand-on vessel is on the right.

**Rule 16 — Action by Give-way Vessel**
Take early and substantial action to keep well clear.

**Rule 17 — Action by Stand-on Vessel**
- May take action to avoid collision by own maneuver alone when it becomes apparent the give-way vessel is not taking sufficient action
- Must take action when collision cannot be avoided by give-way vessel alone
- Course change to port for a vessel on your port side is avoided if possible

**Rule 18 — Responsibilities Between Vessels**

Hierarchy (higher number gives way to all above):
1. Vessel not under command (NUC)
2. Vessel restricted in ability to maneuver (RAM)
3. Vessel constrained by draft
4. Vessel engaged in fishing
5. Sailing vessel
6. Power-driven vessel underway

*Note:* Sailing and power vessels give way to NUC, RAM, constrained, and fishing vessels. A power vessel gives way to a sailing vessel.

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### Section III — Conduct in Restricted Visibility (Rule 19)

**Rule 19 — Restricted Visibility**
- Proceed at safe speed adapted to conditions
- Have engines ready for immediate maneuver
- On hearing fog signal apparently forward of beam: reduce to bare steerage or stop
- Avoid alteration of course to port for a vessel forward of beam (except overtaking)
- Avoid alteration toward a vessel abeam or abaft beam

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## Part C — Lights and Shapes (Rules 20–31)

### Lights (Rules 20–22)

**Rule 20 — Application**
Lights required from sunset to sunrise and in restricted visibility.

**Rule 21 — Definitions**
- *Masthead light* — white forward light, 225° arc
- *Side lights* — red (port) and green (starboard), 112.5° each
- *Stern light* — white aft, 135° arc
- *Towing light* — yellow, same arc as stern light
- *All-round light* — 360° arc
- *Flashing light* — 120+ flashes/minute

**Rule 22 — Visibility of Lights**

| Vessel size | Masthead | Side | Stern | All-round |
|---|---|---|---|---|
| ≥ 50 m | 6 nm | 3 nm | 3 nm | 3 nm |
| 12–50 m | 5 nm | 2 nm | 2 nm | 2 nm |
| 7–12 m | 3 nm | 1 nm | 2 nm | 2 nm |
| < 7 m | — | — | — | 2 nm |

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### Light Combinations to Know

**Under power (≥ 50 m):** Two masthead lights (forward lower, aft higher) + sidelights + stern light

**Under power (< 50 m):** One masthead light + sidelights + stern light

**Under sail (underway):** Sidelights + stern light only. *No masthead light when under sail.*

**Sail + engine:** Power-driven vessel rules apply — show cone (point down) by day.

**At anchor (< 50 m):** One white all-round light forward.
**At anchor (≥ 50 m):** White all-round forward + aft.

**Not under command:** Two red all-round lights (vertical). If making way: add sidelights + stern light.

**Restricted in ability to maneuver:** Red-white-red all-round lights (vertical). If making way: add masthead + sidelights + stern.

**Vessel aground:** Anchor lights + two red all-round lights (vertical).

**Towing vessel:** Extra masthead light(s) + yellow towing light instead of (or in addition to) stern light.

**Fishing (trawling):** Green over white all-round (vertical) + sidelights + stern if making way.
**Fishing (other):** Red over white all-round (vertical) + sidelights + stern if making way + white toward gear if gear > 150 m.

**Pilot vessel on duty:** White over red all-round lights.

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### Day Shapes (Rule 28)

| Shape | Vessel Type |
|---|---|
| Black ball | At anchor |
| Black cone (apex down) | Sailing vessel with engine |
| Two black balls (vertical) | Not under command |
| Ball-diamond-ball (vertical) | Restricted in ability to maneuver |
| Black cylinder | Constrained by draft |
| Basket | Engaged in fishing |
| Cone (apex up) | Vessel being towed (if requested) |

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## Part D — Sound and Light Signals (Rules 32–37)

**Rule 32 — Definitions**
- *Short blast* — about 1 second
- *Prolonged blast* — 4–6 seconds

**Rule 33 — Equipment**
- ≥ 12 m: whistle + bell
- ≥ 100 m: also gong

**Rule 34 — Maneuvering and Warning Signals**

| Signal | Meaning |
|---|---|
| 1 short | I am altering course to starboard |
| 2 shorts | I am altering course to port |
| 3 shorts | I am operating astern propulsion |
| 5+ shorts (rapid) | Danger / doubt signal |
| 1 prolonged | Vessel leaving berth |

**Rule 35 — Sound Signals in Restricted Visibility**

| Signal | Vessel |
|---|---|
| 1 prolonged (≤ 2 min) | Power-driven vessel making way |
| 2 prolonged (≤ 2 min) | Power-driven vessel underway but stopped |
| 1 long + 2 short (≤ 2 min) | NUC, RAM, sailing, fishing, towing |
| 1 long + 3 short | Vessel being towed (last vessel) |
| Rapid bell (5 sec, ≤ 1 min) | At anchor (< 100 m) |
| Bell + gong (≤ 1 min) | At anchor (≥ 100 m) |
| 3 strokes + rapid bell + 3 strokes | Vessel aground |

**Rule 36 — Attention Signal**
Five or more short and rapid blasts. Also a light signal of the same pattern.

**Rule 37 — Distress Signals**
Gun fired at ~1 min intervals; continuous foghorn; SOS (···−−−···); MAYDAY by voice; orange smoke; flames; parachute flare; dye; square flag + ball; high-intensity white light flashing; radio alarm signal.

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## Part E — Exemptions (Rule 38)

Older vessels may be exempt from some lighting requirements for a period of years after the rules came into force.

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## Quick Memory Aids

**Starboard right-of-way:** When another vessel is on your starboard side in a crossing situation, YOU give way.

**Lights mnemonic — red over green, sailing machine:** A sailing vessel shows red (port side) and green (starboard) sidelights plus a white stern light. No masthead light while under sail alone.

**The hierarchy:** NUC → RAM → Constrained → Fishing → Sail → Power