Rule 5: every vessel keeps a proper look-out at all times, by sight and hearing and by all available means such as radar and AIS, all round the horizon, not just ahead.
Look-out, safe speed, risk of collision and action to avoid it
5Look-out
1The rule in plain words
Every vessel keeps a proper look-out at all times, by sight, hearing and appropriate available means, to fully appraise the situation and risk of collision.
Who and when?
Your vessel shall maintain a proper look-out at all times. The duty applies to every vessel.
How?
Look and listen: the look-out must be by sight and hearing. Both are part of a proper look-out.
What else do you use?
Also use all available means appropriate in the prevailing circumstances and conditions, such as radar or AIS.
What is it for?
With this look-out, you make a full appraisal of the situation and of the risk of collision.
2Key points
- 1
Universal duty · continuous look-out.
- 2
Sight + hearing → proper look-out.
- 3
Available means = appropriate to the moment.
- 4
Purpose → full situation appraisal + collision risk.
3Frequent mistakes
Wrong: "A look-out matters only when traffic is busy."
Right: Rule 5 requires you to maintain it at all times.
Wrong: "A small leisure craft is outside Rule 5."
Right: The rule says every vessel; it creates no such exemption.
Wrong: "Radar or AIS replace looking and listening."
Right: Radar and AIS add means; they do not replace look-out by sight and hearing.
4Exam keys & interpretation
Exam keys
- If an option exempts an anchored vessel or small leisure craft, reject it: the rule says "every vessel".
- "Radar/AIS" does not replace "sight and hearing": check whether the option adds means or removes the look-out.
- If asked for the purpose, look for a full appraisal of situation and collision risk, not merely detecting another vessel.
How to read it
- "Appropriate" depends on the prevailing circumstances and conditions: use available means that help you make a full appraisal of the situation.
- "As well as" adds means to sight and hearing; it does not turn equipment into a substitute for the look-out.
5Official text
IMO COLREG 1972U.S. Coast Guard — International Navigation Rules (2024)
Full wording of the rule, reproduced from the official source below.
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.Source: U.S. Coast Guard — International Navigation Rules (2024)
Finish this unit
When you've read it, match the terms, then answer three questions. Get them all right to finish the unit; opening the page alone doesn't count.
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