COLREGs & law

Responsibilities between vessels (Rule 18)

Who keeps out of the way of whom — the hierarchy of vessels.

As a rule the more manoeuvrable vessel keeps out of the way. The order (each one keeps clear of those below):

power-driven vessel
sailing vessel (under sail)
vessel engaged in fishing
vessel restricted in her ability to manoeuvre
vessel not under command.

Note: a sailing vessel does NOT always have right of way — she must keep clear of vessels fishing, restricted in their ability to manoeuvre, or not under command.

Sailing vessels among themselves (Rule 12)

Port tack gives way; on the same tack the windward vessel gives way.

When two sailing vessels meet:

Different tacks — the vessel with the wind on her port side keeps clear of the one with the wind on her starboard side.
Same tack — the windward vessel keeps clear of the leeward vessel.
In doubt — if a vessel on port tack cannot tell with certainty whether the other is on port or starboard tack, she keeps clear.

The “tack” is the side the wind comes in on (the opposite side to the main boom).

Overtaking (Rule 13)

The overtaking vessel keeps clear — always.

A vessel overtaking another (approaching from a sector more than 22.5° abaft the beam, i.e. from astern) must keep out of the way — whatever her means of propulsion. A sailing vessel overtaking a power-driven vessel must keep clear too. The obligation ends only when she is finally past and clear.

Head-on situation (Rule 14)

Two power-driven vessels meeting head-on: both alter to starboard.

When two power-driven vessels meet on reciprocal or nearly reciprocal courses so as to involve risk of collision, each alters course to starboard so that they pass port to port. If in doubt, assume this situation exists.

Crossing situation (Rule 15)

The vessel with the other on her starboard side keeps clear.

When the courses of two power-driven vessels cross so as to involve risk of collision, the vessel that has the other on her own starboard side keeps out of the way. She shall, if the circumstances admit, avoid crossing ahead of the other vessel. The other vessel keeps her course and speed.

In the appThis term comes with a drawing in the Keelwake app.

Lights: power-driven vessel

Masthead light, sidelights, sternlight.

A power-driven vessel under way shows:

a white masthead light forward, shining ahead;
sidelights — green to starboard, red to port;
a white sternlight.

Vessels of 50 m and over carry a second, higher masthead light abaft the first. The colours you can see tell you the other vessel's aspect (e.g. red only = you are looking at her port side).

In the appThis term comes with a drawing in the Keelwake app.

Lights: sailing vessel

Sidelights and sternlight — but no masthead light.

A vessel under sail shows sidelights (green/red) and a white sternlight, but NO masthead light. That is how you recognise a sailing vessel at night. Smaller sailing yachts (under 20 m) may carry a tricolour lantern at the masthead instead of the three separate lights. As soon as the engine is running, the boat counts as a power-driven vessel and must also show the masthead light.

Vessels at anchor & shapes

All-round white light by night, black ball by day.

A vessel at anchor shows an all-round white light forward at night; vessels of 50 m and over a second one aft and lower. By day a black ball is carried in the fore part. Vessels not under command show two red all-round lights, or two black balls in a vertical line.

Sound signals

Manoeuvring and warning signals on the ship's whistle.

Manoeuvring and warning signals (when in sight of one another):

1 short blast — “I am altering my course to starboard.”
2 short blasts — “… to port.”
3 short blasts — “I am operating astern propulsion.”
5 or more short blasts — doubt or warning.

In restricted visibility separate fog signals apply (e.g. one prolonged blast every 2 min for a power-driven vessel making way).

Traffic separation schemes (Rule 10)

Follow the traffic flow, keep clear of the separation zone, cross at right angles.

In a traffic separation scheme (TSS) you proceed in the established direction of traffic flow for that lane and keep clear of the separation zone. If you have to cross, do so on a heading as nearly as practicable at right angles to the direction of traffic flow, so as to leave the lane quickly. Small vessels and sailing vessels must not impede the safe passage of power-driven vessels.

Look-out (Rule 5)

The basic duty that stands above all the steering rules.

Rule 5 requires a proper look-out at all times by sight and hearing and by all available means — eyes, ears, and where appropriate radar and AIS. The aim is to make a full appraisal of the situation and of the risk of collision. Only the look-out makes timely avoiding action possible at all.

Safe speed (Rule 6)

Fast enough only that timely action and stopping remain possible.

Rule 6 requires a safe speed at all times, allowing proper and effective action to be taken and the vessel to be stopped within a distance appropriate to the circumstances. Factors include visibility, traffic density, manoeuvrability, wind and sea state, proximity of shoals and — where radar is used — its characteristics and limitations.

Restricted visibility (Rule 19)

In fog different rules apply — there is no stand-on privilege.

In or near an area of restricted visibility (fog, rain, darkness), Rule 19 applies: safe speed, engines ready for immediate manoeuvre, fog signals sounded. There is no stand-on privilege here as there is when vessels are in sight of one another.

If you have a contact on radar alone, take avoiding action early and generously. So far as possible avoid: an alteration to port for a vessel forward of the beam, and any alteration towards a vessel abeam or abaft the beam.

See alsoSound signals · Safe speed (Rule 6) · fog

Narrow channels (Rule 9)

In channels, keep as near to the starboard side as is safe.

In narrow channels and fairways you keep as near to the starboard side as is safe and practicable. Vessels under 20 m, sailing vessels and vessels engaged in fishing must not impede a vessel that can safely navigate only within the channel. Do not cross the channel unnecessarily, and do not force an overtaking at a narrow point.