Rule 12 — Which Sailing Vessel Keeps Clear

What the rule requires

Rule 12 switches on when two sailing vessels are approaching one another so as to involve risk of collision 33 CFR §83.12. Both conditions matter. Two sailing vessels in company on parallel courses with no risk of collision are not in a Rule 12 situation, and one sailing vessel meeting a power-driven vessel is never in one.

A sailing vessel is any vessel under sail provided that propelling machinery, if fitted, is not being used 33 CFR §83.03. The definition is the same word for word under International COLREGs Rule 3. The moment the engine is put in gear she is a power-driven vessel and Rule 12 no longer reaches her, sails set or not.

The rule then gives three cases, and the whole of the tested content is in them.

• Wind on different sides. The vessel which has the wind on the port side shall keep out of the way of the other.
• Wind on the same side. The vessel which is to windward shall keep out of the way of the vessel which is to leeward.
• Doubt. If a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether that vessel has the wind on the port or on the starboard side, she shall keep out of the way of the other.

Read the doubt case exactly as written. It instructs one vessel only: the vessel with the wind on her port side, looking at a vessel to windward. A starboard-tack vessel unsure of the other's tack is given no corresponding instruction by Rule 12 COLREGs Rule 12. Examiners write distractors that invert this.

Fixing which side the wind is on

Rule 12 does not leave "windward" to judgement. The windward side is the side opposite to that on which the mainsail is carried. In a square-rigged vessel it is the side opposite to that on which the largest fore-and-aft sail is carried .

That gives you a mechanical test rather than a feel for the breeze. Main carried out to starboard, wind is on the port side, port tack, you are the give-way vessel against anyone on starboard tack. Main carried to port, wind on the starboard side, starboard tack.

The common motto in circulation is "port tack gives way", and it is sound as far as it goes. It covers only the different-tacks case. It says nothing at all about two vessels on the same tack, which is where most of the wrong answers get picked, so carry the second half with it: same tack, windward gives way.

Two sailing vessels are converging, both with the wind on the starboard side. You are the vessel to windward. Who keeps clear?

You do. With the wind on the same side, the windward vessel keeps out of the way of the leeward vessel . "Starboard tack" decides nothing here — both vessels are on starboard tack, so the different-tacks case never engages.

Where Rule 12 sits among the other rules

Rule 12 belongs to the section that applies to vessels in sight of one another COLREGs Rule 11. Vessels are deemed in sight of one another only when one can be observed visually from the other . A fog signal heard from a sailing vessel you cannot see does not put you into Rule 12 at all.

Between different classes of vessel, the ranking is in Rule 18. A power-driven vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel engaged in fishing, and a sailing vessel. A sailing vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to manoeuvre, and a vessel engaged in fishing COLREGs Rule 18.

Taught as a ladder, sail sits one rung below fishing and above power. Two cautions on the ladder. It is expressly subject to Rules 9, 10 and 13, and the duty owed to a vessel constrained by her draft is weaker than the others — the obligation there is to avoid impeding her safe passage if the circumstances of the case admit, not to keep out of the way. Rule 18 is also one of the rules where the Inland text is not identical to the International, so treat an "(Inland Only)" question on responsibilities between vessels as its own problem.

Rule 12 itself carries no such caveat. Inland Rule 12 is word-for-word identical to COLREGs Rule 12.

Telling it apart

One criterion sorts every Rule 12 question: which side each vessel has the wind on, established from where she carries her mainsail. Everything else in the scenario is dressing.

• Different sides. Port-tack vessel gives way, starboard-tack vessel is the other vessel. Most often misfiled when the candidate identifies tack from the drawn heading relative to the wind arrow instead of from the sail carriage, and gets the tack backwards.
• Same side, you to windward. You give way. Misfiled by candidates who see "starboard tack" in the stem and stop reading.
• Same side, you to leeward. The other vessel gives way. Misfiled when a candidate assumes the vessel to leeward, being downwind and slower to manoeuvre, must therefore be the burdened one.
• Port tack, other vessel to windward, her tack uncertain. You keep out of the way. The uncertainty resolves against you, not in your favour.
• Machinery engaged. She is not a sailing vessel and no part of Rule 12 applies. This is the one that changes the answer completely rather than by one step.

Working a question

You are on watch on a 38-foot auxiliary sloop, engine secured, making 6 knots on a course of 070°T. You sight a second sailing vessel fine on the starboard bow at about a mile, her bearing steady, her mainsail clearly carried out over her port side. Your own main is out over your starboard side.

1. Confirm both are sailing vessels. Your engine is secured and sails are drawing, so you meet the definition. Nothing in the scenario says the other vessel is under power COLREGs Rule 3.
2. Confirm the rule is in force. She is visually observed from your vessel, so you are in sight of one another, and the steady bearing at closing range means risk of collision exists. Both triggers are satisfied.
3. Fix your own wind side. Your main is carried to starboard. The windward side is the side opposite the mainsail, so your wind is on the port side. You are on port tack.
4. Fix hers. Her main is carried to port, so her wind is on the starboard side. Starboard tack.
5. Select the case. Each has the wind on a different side, so the first case governs — not the windward-leeward case, which never enters a different-tacks problem.
6. Name the duty. The vessel with the wind on the port side keeps out of the way. That is you 33 CFR §83.12.
7. Test the alternative reading. Had her main also been carried to starboard, both would have the wind on the port side, the case would shift to same-side, and the duty would fall on whichever of you lay to windward.

Now change one fact. You start the engine and put it in gear to work clear, leaving the sails set. You are now a power-driven vessel, and a power-driven vessel underway keeps out of the way of a sailing vessel COLREGs Rule 18 — the duty still runs to you, but from a different rule, and your required lights change with it.

Where candidates lose the point

Picking "starboard tack stands on" for a same-tack question. The motto is drilled hard enough that candidates apply it to a stem where both vessels have the wind on the same side. When the wind is on the same side, tack is irrelevant and windward gives way to leeward.

Reading the doubt case as symmetric. A stem placing you on starboard tack, unsure of the other vessel's tack, does not attract the doubt provision — that provision addresses the vessel with the wind on her port side seeing a vessel to windward COLREGs Rule 12.

Determining windward from the boom, the burgee or apparent wind on the face. The rule fixes it by the side on which the mainsail is carried, and for a square-rigger by the side on which the largest fore-and-aft sail is carried. A square-rig stem is a deliberate trap: the candidate looks for a mainsail and answers from the yards.

Treating a motorsailing vessel as a sailing vessel. With machinery being used she is power-driven 33 CFR §83.03, which also decides the lights question. A sailing vessel underway exhibits sidelights and a sternlight, and if less than 20 metres in length these may be combined in one lantern carried at or near the top of the mast — the same under Inland COLREGs Rule 25. Under power she exhibits a masthead light forward, sidelights and a sternlight, with the second masthead light not obligatory below 50 metres in length COLREGs Rule 23.

Applying Rule 12 to a vessel heard but not seen. Section II reaches vessels in sight of one another only, and in sight means one can be observed visually from the other.

Assuming the rule protects you once you have identified yourself as the other vessel. Nothing in the Rules exonerates a vessel, her owner, master or crew from the consequences of neglecting any precaution required by the ordinary practice of seamen or by the special circumstances of the case, and a departure from the Rules may be necessary to avoid immediate danger COLREGs Rule 2. Inland Rule 2 is identical.

Check yourself

You are under sail with the wind on your port side. You sight a sailing vessel to windward and cannot determine with certainty which tack she is on. What are you required to do?

Keep out of the way of the other vessel. The doubt provision resolves against the vessel with the wind on the port side 33 CFR §83.12.

Your mainsail is carried out over the port side. Which is your windward side, and which tack are you on?

Windward is starboard, the side opposite the mainsail, so you are on starboard tack COLREGs Rule 12.

Both vessels have the wind on the port side. You are to leeward. Who is the give-way vessel?

The other vessel. With the wind on the same side, windward keeps out of the way of leeward. Being on port tack does not burden you here, because both vessels are.

You are under sail, engine running and engaged, sails still set and drawing. Another sailing vessel is crossing with risk of collision. What are you?

A power-driven vessel — propelling machinery is being used, so the sailing vessel definition does not apply COLREGs Rule 3. Under Rule 18 a power-driven vessel underway keeps out of the way of a sailing vessel.

(Inland Only) Two sailing vessels are approaching with the wind on different sides. Does the Inland rule change the answer?

No. Inland Rule 12 at 33 CFR §83.12 is word for word the International rule, so the port-tack vessel keeps out of the way on both.

You are under sail and a vessel engaged in fishing is fine on your bow with risk of collision. Which of you keeps clear?

You do. A sailing vessel underway keeps out of the way of a vessel not under command, a vessel restricted in her ability to manoeuvre, and a vessel engaged in fishing COLREGs Rule 18. A vessel fishing with trolling lines that do not restrict manoeuvrability is not a vessel engaged in fishing 33 CFR §83.03, and the answer reverses.

You are under sail in dense fog and hear the fog signal of another sailing vessel ahead. Does Rule 12 tell you who gives way?

No. Rule 12 applies to vessels in sight of one another COLREGs Rule 11, and vessels are in sight only when one can be observed visually from the other. A signal heard through fog does not establish that.