Rule 16 specifies what the give-way vessel must do. Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.
The action must be:
- Early — not last-minute
- Substantial — clearly visible to the other vessel
- Effective — resulting in a safe passing distance
IMO COLREG 1972Official text
Full wording of the rule, reproduced from the official source below.
Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.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.
Build the traffic picture with sight, hearing, radar/ARPA and chart context.
Do not let AIS or one isolated bearing replace systematic observation.
After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.
Exam Focus
Identify the vessel types first, then the relative bearing, then whether one vessel is overtaking.
Misclassifying the encounter is the usual exam failure.
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.
Key Takeaways
Give-way vessel must act early, not wait until the last moment
Action must be substantial and readily apparent
The goal is to keep well clear, not just barely avoid collision
Common Mistakes
Taking action too late when the vessels are already close
Making small course changes that are not apparent to the other vessel
Test Your Knowledge
Practise this topic and review the explanation for each answer.
More rules in this Part
- Sailing VesselsWhen two sailing vessels approach, the one with wind on port side keeps clear. When both have wind on same side, the windward vessel keeps clear.
- OvertakingAny vessel overtaking another shall keep out of the way of the vessel being overtaken.
- Head-on SituationWhen two power-driven vessels in sight meet on reciprocal or nearly reciprocal courses with risk of collision, each shall alter to starboard to pass port to port.
- Responsibilities Between VesselsRule 18 sets the basic responsibilities between vessel types. Constrained-by-draught vessels receive special consideration but are not simply another rung in a fixed hierarchy.
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