The rules of the road for sailboats.

This page paraphrases the navigation rules as published by the US Coast Guard in its amalgamated text of the International and Inland Rules. It is a summary, not the rules themselves. Read the official text, and check which rules apply where you sail with your national or local authority. Information here is current as of October 2026.

Which rules apply

International (COLREGs)

The Convention on the International Regulations for Preventing Collisions at Sea, 1972, was adopted on 20 October 1972 and came into force on 15 July 1977. The UK Maritime and Coastguard Agency states that it applies to all vessels regardless of size.

United States

The US adopted the 1972 rules through the International Navigation Rules Act of 1977. The Coast Guard says they have been amended 86 times, most recently in 2014. Separate Inland Navigation Rules (from the Inland Navigation Rules Act of 1980) apply inside the COLREGS Demarcation Lines set out in 33 CFR 80, and the International Rules apply outside them. The Coast Guard says the two sets are very similar apart from Annex V.

The rules are organized in five parts: Part A General (Rules 1 to 3), Part B Steering and Sailing (4 to 19), Part C Lights and Shapes (20 to 31), Part D Sound and Light Signals (32 to 37) and Part E Exemptions (38), plus Annexes I to IV covering technical details of lights, shapes, sound appliances and distress signals.

US Sailing's Basic Keelboat course and ASA 101 both include the navigation rules, and ASA 101 works from the USCG Navigation Rules handbook.

When a sailboat is a sailboat

Rule 3 defines a sailing vessel as one under sail with any engine not in use. A sailboat with its engine running counts as a power-driven vessel, even with its sails up, and follows the rules for power-driven vessels.

Duties that apply to every vessel

• Lookout (Rule 5). Keep a proper lookout at all times, by sight, by hearing and by every other available means.
• Safe speed (Rule 6). Go at a safe speed, taking account of visibility, traffic, how well the boat maneuvers, wind, sea, current and nearby hazards.
• Risk of collision (Rule 7). If in any doubt, assume a risk of collision exists. An approaching vessel whose bearing does not change much is a warning sign.
• Action to avoid collision (Rule 8). Any action should be positive, made in good time, and large enough for the other vessel to notice. A string of small changes is to be avoided.
• Narrow channels (Rule 9). A sailing vessel, or any vessel under 20 m, must not impede a vessel that can navigate safely only within the channel.

Two sailing vessels meeting (Rule 12)

When two sailing vessels are approaching with risk of collision:

• If they have the wind on different sides, the vessel with the wind on its port side keeps clear of the other.
• If they have the wind on the same side, the vessel to windward keeps clear of the vessel to leeward.
• If a vessel with the wind on its port side cannot tell which side the other vessel has the wind on, it must keep clear.

For this rule, the windward side is defined as the side opposite to the one where the mainsail is carried. Port and starboard tack are explained on points of sail.

Overtaking (Rule 13)

A vessel overtaking another keeps clear of the one being overtaken. Overtaking means coming up from more than 22.5 degrees abaft (behind) the other vessel's beam, which at night means you would see only its sternlight. The rule applies to every vessel, so a sailboat overtaking a powerboat must keep clear. A later change in bearing does not turn an overtaking situation into a crossing one.

Give-way and stand-on

Rules 16 and 17 set out what each vessel does once it is clear which one must keep out of the way. Under Rule 16 the give-way vessel must act early and substantially to keep well clear. Under Rule 17 the stand-on vessel keeps its course and speed. It may take action itself once it becomes clear the give-way vessel is not doing what the rules require, and it must act when collision can no longer be avoided by the give-way vessel alone.

Who keeps clear of whom (Rule 18)

Sail does not always have priority. Rule 18 sets out a hierarchy:

The hierarchy sits alongside the overtaking and narrow channel rules above; as Rule 13 makes clear, a sailboat overtaking a powerboat still keeps clear. Rule 18(d), on vessels constrained by their draft, exists in the International Rules only.

Lights

The federal requirements guide says navigation lights must be shown from sunset to sunrise and in restricted visibility.

• Sailing vessel under way (Rule 25). Sidelights and a sternlight. A sailing vessel under 20 m may combine them in one lantern at or near the top of the mast. It may also show all-round red-over-green lights at the masthead, but not together with that combined lantern.
• Under 7 m. A sailing vessel this small should show sailing lights if practicable. If not, it must have a white torch or lantern ready to show in time to prevent a collision.
• Motorsailing by day. A vessel under sail with its engine running shows a cone, point down, forward. Under the Inland Rules, vessels under 12 m are exempt.
• At anchor (Rule 30). An all-round white light. Vessels under 7 m anchored away from channels and normal anchorages are exempt, and under the Inland Rules so are vessels under 20 m in a designated special anchorage.

Sound signals

• Blasts (Rule 32). A short blast lasts about 1 second; a prolonged blast lasts 4 to 6 seconds.
• Equipment (Rule 33). Vessels of 12 m or more carry a whistle, 20 m or more add a bell, and 100 m or more add a gong. Vessels under 12 m need some other means of making an efficient sound signal.
• Maneuvering signals (Rule 34). One short blast means altering course to starboard, two short blasts altering to port, and three short blasts operating astern propulsion. Five or more short, rapid blasts signal doubt about the other vessel's intentions. Under the International Rules these signals are for power-driven vessels in sight of one another, and the Inland version differs.
• Restricted visibility (Rule 35). A sailing vessel under way sounds one prolonged blast followed by two short blasts, at intervals of no more than 2 minutes.

Distress signals

Rule 37 and Annex IV list the recognized signals of distress. They include continuous sounding of a fog signal, red rockets or flares, SOS, the spoken word "Mayday" by radio, orange smoke, slowly raising and lowering outstretched arms, DSC alerts and EPIRB signals. The Inland Rules add a high-intensity white light flashing 50 to 70 times a minute. US Sailing's Basic Keelboat course teaches distress signaling, and the carriage rules for signals are on safety requirements.

Racing is different

Boats racing each other also follow the Racing Rules of Sailing, a separate rulebook. Some rules look alike: under racing rule 10, a port-tack boat keeps clear of a starboard-tack boat. The racing rulebook is a separate document from the navigation rules. See racing rules.