Rule 5: keep a proper look-out. Always.

What does COLREGs Rule 5 say?

Every vessel must keep a proper look-out at all times — 'by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions' — so that it can make a full appraisal of the situation and of the risk of collision.

It sits in Part B, Section I, so by Rule 4 it applies in any condition of visibility: clear, at night or in fog.

Who does Rule 5 apply to?

Every vessel. The rule makes no exception for size, type or what the vessel is doing, and it says 'at all times'. What changes with the circumstances is how much look-out is proper — not whether one is kept.

What counts as 'all available means'?

Anything on board that helps you see the situation, used as the circumstances require: radar, AIS, ECDIS, VHF, binoculars, and simply opening a bridge-wing door to listen. Rule 7(b) adds that radar, if fitted and operational, must be used properly — including long-range scanning for early warning and plotting, or equivalent systematic observation, of what it detects.

Can radar or AIS be the look-out?

No. They are means of keeping one, and the rule names sight and hearing first. Small craft, sailing vessels and some hazards may not show on radar or carry AIS, and AIS shows only what another vessel transmits. A look-out that relies on a screen alone is not a full appraisal.

Why does the rule say 'hearing'?

Because some warnings only arrive as sound: fog signals, manoeuvring signals, a call for help. On an enclosed bridge in restricted visibility, that can mean opening a door to listen. Rule 19(e) turns on hearing a fog signal forward of the beam — you cannot comply with it if you cannot hear one.

Can the officer of the watch be the sole look-out?

Only in daylight, and only on conditions set by the STCW Code (Section A-VIII/2): the situation has been carefully assessed and it is established without doubt that it is safe; full account is taken of weather, visibility, traffic, dangers to navigation and any traffic separation scheme; and help can be summoned to the bridge at once if the situation changes. At night, the OOW is not the sole look-out.

How might Rule 5 come up in an MCA oral?

It may come up inside a scenario rather than as 'recite Rule 5'. Examples of the kind of question to be ready for:

“You're alone on the bridge at night in good visibility. Is that a proper look-out?”

“What changes about your look-out when the visibility closes in?”

“What are the limitations of AIS as part of your look-out?”

“What does the look-out do while you're at anchor?”

Where do candidates go wrong on Rule 5?

The common slips: treating the radar or AIS as the look-out, forgetting that the rule says hearing, and not being able to give the conditions for the OOW acting as sole look-out. Saying the rule word for word matters less than showing you apply it on watch.