This memory aid is not a substitute for the full rule. The relative positions, vessel types, restricted channels and other circumstances can change which rules apply.

Overtaking: Rule 13

A vessel overtaking another must keep out of the way of the vessel being overtaken.

An overtaking vessel is generally one approaching from a direction more than 22.5 degrees abaft the other vessel’s beam. At night, this corresponds to a position where the overtaking vessel would see the sternlight but neither sidelight of the vessel ahead.

If you are uncertain whether you are overtaking, you must assume that you are and act accordingly.

The obligation to keep clear continues until the overtaking vessel is finally past and clear. Do not assume the other vessel will change course to accommodate you.

Sailing vessels: Rule 12

When two sailing vessels are approaching one another with a risk of collision, Rule 12 establishes responsibilities based on their wind positions and tack.

• When the vessels have the wind on different sides, the vessel with the wind on her port side must keep out of the way of the other.
• When both vessels have the wind on the same side, the windward vessel must keep out of the way of the leeward vessel.
• If a vessel with the wind on her port side sees another sailing vessel to windward and cannot determine whether that vessel has the wind on her port or starboard side, she must keep out of the way.

These rules apply to sailing vessels under sail in the circumstances covered by the regulation. If a sailing vessel is using its engine, it may be treated as a power-driven vessel under the COLREGs, depending on its status and the applicable definitions.

Responsibilities between different vessel types: Rule 18

Rule 18 sets out responsibilities between vessels, subject to exceptions elsewhere in the rules.

In broad terms, a power-driven vessel underway must keep out of the way of certain vessels, including:

• A vessel not under command.
• A vessel restricted in her ability to manoeuvre.
• A vessel engaged in fishing.
• A sailing vessel.

The precise obligations depend on the vessel’s status and the circumstances. Vessels constrained by their draft also have a specific status under the international rules, and other provisions may affect the encounter.

Do not reduce Rule 18 to a simple hierarchy. The definitions, exceptions and other applicable rules must be considered before deciding which vessel must manoeuvre.

5. Narrow channels and traffic separation schemes

Some waters require additional navigation discipline because vessels have limited room to manoeuvre or follow organised traffic routes.

Rule 9: Narrow channels

Vessels navigating along a narrow channel or fairway must comply with the specific requirements of Rule 9.

Among other provisions, a vessel proceeding along the course of a narrow channel or fairway should keep as near to the outer limit of the channel or fairway on her starboard side as is safe and practicable.

Small vessels and sailing vessels must not impede the passage of vessels that can safely navigate only within the channel or fairway, subject to the wording and conditions of the rule.

A skipper should plan ahead, monitor traffic and avoid manoeuvres that could leave insufficient room for another vessel to pass safely.

Rule 10: Traffic separation schemes

Traffic separation schemes organise vessel movements into designated traffic lanes and separation zones.

When using a scheme, vessels must follow the relevant rules for entering, leaving, crossing and navigating within it. A vessel crossing a traffic lane should do so as nearly as practicable at right angles to the general direction of traffic flow, as required by Rule 10.

A recreational boat should not assume that a traffic separation scheme is simply a marked route to follow at any angle. Check the chart, understand the scheme and minimise interference with vessels using the lanes.

6. Navigation lights and shapes: Rules 20–31

The COLREGs specify the lights and shapes vessels must display to communicate their status and activity.

These signals help other vessels understand whether a boat is power-driven, sailing, fishing, towing, anchored or experiencing restricted manoeuvrability.

Examples include:

• Power-driven vessels underway: prescribed masthead light or lights, sidelights and sternlight, depending on vessel length and configuration.
• Sailing vessels underway: sidelights and a sternlight, with specific permitted arrangements and additional lights in certain circumstances.
• Vessels at anchor: prescribed anchor light or lights and, where required, shapes.
• Vessels not under command: prescribed red lights and shapes.
• Vessels restricted in their ability to manoeuvre: prescribed red-white-red lights and corresponding shapes, subject to the rules.
• Vessels engaged in fishing: specific lights and shapes according to the activity and conditions.

The exact requirements depend on vessel type, length, activity and circumstances.

For a practical explanation of the lights you may see at sea, read Boat Navigation Lights Explained.

Lights are not only for night navigation. The COLREGs contain requirements for lights and shapes in different conditions, and local regulations or the specific circumstances may impose additional obligations.

7. Sound signals and restricted visibility

The COLREGs also prescribe sound signals, including signals for manoeuvring, warning and restricted visibility.

Sound signals are especially important when vessels cannot see one another clearly. Their meaning depends on the signal, the vessel’s status and the circumstances.

In restricted visibility, Rule 19 applies to vessels that are not in sight of one another when navigating in or near an area of restricted visibility.

Key principles include:

• Proceed at a safe speed adapted to the conditions.
• Keep engines ready for immediate manoeuvre when required for a power-driven vessel.
• Use radar appropriately and assess whether a risk of collision exists.
• Take avoiding action when required, while accounting for the limitations of radar information.
• If a fog signal is heard apparently forward of the beam, or a close-quarters situation with a vessel forward of the beam cannot be avoided, reduce speed to the minimum at which the vessel can be kept on course, take all way off if necessary and navigate with extreme caution.

Do not treat fog signals as a replacement for lookout, radar assessment or other precautions.

For a more detailed explanation, read Rule 19: Collision Avoidance in Restricted Visibility.

8. A practical COLREGs checklist

Use this checklist when approaching other vessels or entering busy waters.

• Maintain a proper lookout by sight, hearing and all appropriate available means.
• Choose a safe speed for visibility, traffic, manoeuvrability and conditions.
• Assess collision risk early and continue monitoring the situation.
• Identify which rules apply: crossing, head-on, overtaking, sailing-vessel encounter or another situation.
• Determine whether your vessel must give way or stand on.
• If required, take early, substantial and readily apparent action.
• Confirm that the manoeuvre has created a safe passing distance.
• Display the correct navigation lights and shapes.
• Use the prescribed sound signals when applicable.
• In restricted visibility, apply Rule 19 and take additional precautions.
• Follow local regulations, traffic separation schemes and instructions from the relevant authorities.

9. Record your navigation and incidents in a boat logbook

Understanding the COLREGs is part of safe navigation, but reviewing what happened during a trip can also help you improve your decision-making.

A boat logbook can record useful context such as:

• Date, time and position.
• Weather, wind and visibility.
• Route and GPS track.
• Encounters with other vessels that were relevant to the trip.
• Safety warnings or instructions received.
• Any incident, manoeuvre or lesson worth reviewing.

If an incident occurs, record facts as accurately as possible, including the sequence of events, the vessels involved, relevant conditions and actions taken. Distinguish observations from assumptions, and preserve any other records that may be relevant.

With Skipper, you can document boating trips with GPS tracks, locations, notes and photos, then review your trip history later.

Conclusion

The COLREGs provide the shared framework that allows vessels to navigate safely around one another. The most important starting points are to maintain a proper lookout, proceed at a safe speed, assess collision risk early and take effective action when necessary.

Learn the rules that apply to your vessel and navigation area, and do not rely on simplified rules of thumb when the situation is complex. The stand-on vessel is not guaranteed an unconditional right of way, and every skipper must continue to act responsibly to avoid collision.

Safe navigation depends on understanding the rules, applying them in context and staying alert to what other vessels are doing.

Frequently asked questions

What does COLREG stand for?

COLREG stands for the International Regulations for Preventing Collisions at Sea. These rules establish internationally agreed requirements for vessel conduct, collision avoidance, lights, shapes and sound signals.

Which vessel has right of way at sea?

The COLREGs do not provide an unconditional right of way. They define which vessel must keep out of the way and which should normally maintain course and speed. Both vessels must still take appropriate action to avoid collision when the circumstances require it.

What is the difference between a give-way vessel and a stand-on vessel?

The give-way vessel must take early and substantial action to keep clear. The stand-on vessel should normally maintain course and speed, but must act when it becomes apparent that the give-way vessel is not taking appropriate action.

What should I do in a head-on situation?

When two power-driven vessels meet on reciprocal or nearly reciprocal courses with a risk of collision, each should alter course to starboard so they pass port-to-port, unless the circumstances or applicable rules require otherwise.

Do the COLREGs apply to recreational boats?

Yes. The international rules generally apply to vessels on the high seas and connected navigable waters. Local and inland rules may also apply, so boaters must know the regulations relevant to their location.