Module 5 - COLREGs
Stand-On and Give-Way Obligations
What you will learn
Manage the Rule 16 and Rule 17 timeline with clear evidence for the initial duty, the stand-on may-act stage and the later must-act stage.
Stand-on and give-way roles create a predictable first plan. They do not freeze either vessel while collision risk develops.
Rule 16 requires every give-way vessel, so far as possible, to take early and substantial action to keep well clear. The action must also meet Rule 8: clear, timely, lawful, safe around other traffic and monitored to safe passing distance.
Rule 17(a)(i) initially requires the stand-on vessel to keep course and speed. Rule 17(a)(ii) allows her to take action by her manoeuvre alone as soon as it becomes apparent that the give-way vessel is not taking appropriate action. This may-act stage should not be delayed until only emergency choices remain.
Rule 17(b) creates the must-act stage: when collision cannot be avoided by the give-way vessel's action alone, the stand-on vessel must take the action that will best aid avoidance. In a two-power crossing, a stand-on vessel acting under Rule 17(a)(ii) should, if circumstances admit, avoid altering to port for a vessel on her own port side. No universal range or TCPA divides the stages, and VHF does not suspend the Rules.
Worked example
Your power-driven yacht is stand-on in a crossing. The give-way vessel remains steady through successive observations and available sea room is reducing.
- 1Continue course and speed initially while plotting the contact and checking secondary hazards.
- 2When failure to act becomes apparent, consider an early Rule 17(a)(ii) manoeuvre and avoid port for the vessel on your port side if circumstances admit.
- 3If the give-way vessel alone can no longer avoid collision, take the action that will best aid avoidance.
Sense check: Waiting for a fixed one-mile threshold can miss both the geometry and the yacht's manoeuvring limits.
Brief escalation before the encounter tightens
A watchkeeper calls the yacht stand-on but has not agreed when to call the skipper or what shows the give-way vessel is failing.
1. Name expected action
State what early and substantial change should become apparent.
2. Set evidence-based triggers
Use bearing, range, TCPA trend, sea room and uncertainty rather than one distance.
3. Keep an escape plan
Identify safe manoeuvre space and secondary contacts before the may-act stage.
Sense check: 'We are stand-on' is incomplete unless the team knows escalation evidence and available action.
Common mistake or limitation
- Stand-on does not mean hold course and speed until collision is inevitable; Rule 17 has may-act and must-act stages.
- A private VHF agreement cannot replace the Rules or make a late manoeuvre predictable.
Recap
- The give-way vessel acts early and substantially to keep well clear.
- The stand-on vessel may act when failure becomes apparent and must act when the give-way vessel alone cannot avoid collision.
- Use evidence-based triggers and preserve manoeuvring options rather than relying on universal distance.
Optional quick check
Section 8 of 14
What distinguishes Rule 17(b) from the earlier Rule 17(a)(ii) stage?
Sources and factual review
Reviewed 2 September 2026 - Compass Revision editorial review.
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