Sailing vessels
In plain language
When two sailing vessels approach so as to involve risk of collision: with wind on different sides, the one with wind on the port side keeps out of the way; with wind on the same side, the windward vessel keeps clear; if a vessel with wind to port sees a vessel to windward and cannot tell which side her wind is on, she keeps out of the way.
Full text of Rule 12
When two sailing vessels are approaching one another, so as to involve risk of collision, one of them shall keep out of the way of the other as follows: (i) when 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; (ii) when both have the wind on the same side, the vessel which is to windward shall keep out of the way of the vessel which is to leeward; (iii) if 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.
For the purposes of this Rule the windward side shall be deemed to be the side opposite to that on which the mainsail is carried or, in the case of a square-rigged vessel, the side opposite to that on which the largest fore-and-aft sail is carried.
Reproduced from the COLREGs 1972 (as amended) for study. Always verify against the official IMO publication.
Key points
- 1
Different tacks — port tack gives way.
- 2
Same tack — windward vessel gives way.
- 3
In doubt about the other's tack, the port-tack vessel keeps clear.
- 4
Windward side is the side opposite that on which the mainsail is carried.