Rule 5 is one of the most important rules in the Convention. 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.
A proper look-out is not just "someone on the bridge". It means a continuous, attentive watch using sight, hearing and all appropriate aids such as radar, ARPA and AIS if fitted, while remembering that electronic aids support rather than replace human appraisal.
The purpose of the look-out is twofold: to detect hazards early and to build an accurate understanding of what those hazards mean for the ship's safety and for collision risk.
IMO COLREG 1972Official text
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.STCW Bridge Watch Lens
Rules 4–10 apply in any visibility.
Rules 11–18 apply to vessels in sight of one another; Rule 19 applies to vessels not in sight when navigating in or near an area of restricted visibility.
A proper look-out means a person who can give full attention to the task and a bridge team using all appropriate means without over-reliance on one sensor.
After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.
Exam Focus
Start every scenario by classifying the encounter: overtaking, head-on, crossing, narrow channel, traffic separation, or restricted visibility.
For vessels in sight, every overtaking vessel keeps clear until finally past and clear.
Rule 13 takes precedence over Part B Sections I and II; it does not override the other Parts of COLREG.
Watch for trick answers that replace look-out with AIS, VHF or one quick radar glance.
The rule demands a full appraisal of the situation.
Apply Rule 5: two lookout decisions
COLREG · USCG NAVCEN · 2026-09-10Near a harbour at night, a small boat's light is visible against bright shore lights, but the radar shows no clear echo. The watchkeeper has been looking only at the display.
Can the radar picture justify dismissing the boat?
No. Restore an attentive visual and hearing watch, report the observed light, and use the available radar appropriately alongside those observations. Keep observing the boat systematically to assess its movement and collision risk.
Rule 5 combines sight, hearing and appropriate available means. Small targets may escape radar detection, and shore lights can mask navigation lights. A missing echo is not evidence that a visible boat or collision risk has disappeared.
Your vessel is anchored in clear daylight near passing traffic. The crew proposes leaving the lookout unattended because the engine is stopped and visibility is good.
Does being at anchor remove the lookout duty?
No. Maintain an effective lookout by sight and hearing, using other appropriate available means. Arrange relief before other duties interrupt that watch, and continue assessing approaching traffic and changes around the vessel.
Rule 5 applies to every vessel at all times. Anchoring and good weather do not remove the need to detect and appraise hazards; the means used must suit the actual conditions.
Key Takeaways
A proper look-out is required at all times, in all visibility conditions
Electronic aids support the look-out but do not replace sight and hearing
The watch must make a full appraisal of the situation, not just detect targets
A distracted or overloaded watchkeeper is not maintaining a proper look-out
Common Mistakes
Relying on radar or AIS instead of maintaining a visual and aural watch
Giving the look-out other duties that break concentration
Relaxing the look-out because the weather appears clear or traffic seems light
Test Your Knowledge
Practise this topic and review the explanation for each answer.
More rules in this Part
- Risk of CollisionEvery vessel shall use all available means to determine if risk of collision exists. If in doubt, such risk shall be deemed to exist.
- Action to Avoid CollisionAny action to avoid collision shall be positive, made in ample time, and with due regard to good seamanship.
- Narrow ChannelsA vessel proceeding along the course of a narrow channel shall keep as near to the outer limit of the channel which lies on her starboard side.
- Traffic Separation SchemesVessels using traffic separation schemes shall proceed in the appropriate traffic lane in the general direction of traffic flow.
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