Rule 12 governs the interaction between two sailing vessels.
- 1When each has the wind on a different side, the vessel which has the wind on the port side shall keep out of the way of the other
- 2When both have the wind on the same side, the vessel which is windward shall keep out of the way of the vessel which is leeward
- 3If a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether the other vessel has the wind on the port or on the starboard side, she shall keep out of the way of the other.
STCW Bridge Watch Lens
Decide applicability before manoeuvring: Rules 4-10 apply in any visibility, Rules 11-18 only when vessels are in sight, and Rule 19 governs radar-only encounters in 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.
If two rules seem to conflict, check the order carefully: overtaking duties still apply, and Rule 2 still requires ordinary seamanship.
Key Takeaways
Port tack gives way to starboard tack
Windward vessel gives way to leeward when on same tack
If in doubt about other vessel's tack, keep clear
Only applies between two sailing vessels
Common Mistakes
Applying these rules when one vessel is motor-sailing (engine on)
Confusing windward/leeward with port/starboard
Test Your Knowledge
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More rules in this Part
- Head-on SituationWhen two power-driven vessels are meeting head-on, each shall alter course to starboard to pass port to port.
- Crossing SituationWhen two power-driven vessels are crossing, the vessel which has the other on her starboard side shall keep out of the way.
- Action by Give-way VesselEvery vessel directed to keep out of the way shall take early and substantial action to keep well clear.
- Action by Stand-on VesselThe stand-on vessel shall keep her course and speed, but may take action when it becomes apparent the give-way vessel is not acting.
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