Rule 12 — Sailing Vessels: Right-of-Way Between Sail

TL;DR — When two sailing vessels meet with risk of collision, the vessel on the port tack gives way; if both are on the same tack, the windward vessel gives way. A vessel under sail that is also using its engine is treated as a power-driven vessel and must display a cone, apex down. 33 CFR §83.12 33 CFR §83.25

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What the Rule Says

Applicability: "Sailing Vessel" Defined

Before Rule 12 can apply, both vessels must qualify as sailing vessels. Under the Inland Rules, a "sailing vessel" means any vessel under sail provided that propelling machinery, if fitted, is not being used. 33 CFR §83.03 The moment the engine is engaged, the vessel loses sailing-vessel status and becomes a power-driven vessel for purposes of the Rules — with all the give-way obligations that entails. 33 CFR §83.03

The Three Scenarios of Rule 12

Rule 12 addresses only the situation of two sailing vessels approaching one another so as to involve risk of collision. It establishes a clear priority order through three distinct scenarios. 33 CFR §83.12

Scenario 1 — Different tacks (wind on opposite sides). When each vessel 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. 33 CFR §83.12 In plain terms: port tack gives way to starboard tack. This is the most frequently tested scenario on the OUPV and Master 100 GT written exams.

Scenario 2 — Same tack (wind on the same side). When both vessels 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. 33 CFR §83.12 The leeward vessel is the stand-on vessel. This scenario is tested less often than Scenario 1 but appears regularly in multi-step situational questions.

Scenario 3 — Uncertainty about the other vessel's tack. 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. 33 CFR §83.12 This is a precautionary rule: when in doubt, the port-tack vessel yields. The rule does not require the uncertainty to be reasonable or prolonged — any genuine inability to determine the other vessel's tack triggers the obligation.

Defining "Windward Side"

The Rule provides its own working definition of windward side to eliminate ambiguity in practice. For the purpose of Rule 12, the windward side is 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. 33 CFR §83.12

This definition is operationally important: it ties the determination of windward side to observable sail trim rather than to the direction of the apparent or true wind. On a vessel sailing downwind with the boom well out to one side, the windward side is the side opposite the boom — regardless of where the wind appears to be coming from at any given moment.

Sailing Vessel Lights and the "Motorsailer" Shape

Rule 25 governs the lights and shapes a sailing vessel must exhibit, and it contains a critical provision that connects directly to Rule 12 status. 33 CFR §83.25

A sailing vessel underway shall exhibit sidelights and a sternlight. 33 CFR §83.25 A sailing vessel of less than 20 meters may combine those lights into a single tricolor lantern at or near the top of the mast. 33 CFR §83.25 A sailing vessel may additionally exhibit two all-round lights in a vertical line at or near the masthead — red over green — but those optional lights shall not be exhibited in conjunction with the combined tricolor lantern. 33 CFR §83.25

For vessels under 7 meters, the Rule requires the prescribed lights if practicable; if not practicable, an all-round white light or a torch ready at hand, exhibited in sufficient time to prevent collision. 33 CFR §83.25 A vessel under oars has the same option. 33 CFR §83.25

The provision most directly tied to Rule 12 status: a vessel proceeding under sail when also being propelled by machinery shall exhibit forward, where it can best be seen, a conical shape, apex downward. 33 CFR §83.25 A vessel of less than 12 meters is not required to exhibit this shape but may do so. 33 CFR §83.25 The cone is the daytime signal that tells every other vessel: this vessel is a power-driven vessel for purposes of the Rules, not a sailing vessel.

Where Sailing Vessels Fit in the Overall Hierarchy

Rule 12 governs only the relationship between two sailing vessels. The broader hierarchy of vessel types is established by Rule 18. Under Rule 18, a sailing vessel underway shall keep out of the way of a vessel not under command, a vessel restricted in her ability to maneuver, and a vessel engaged in fishing. 33 CFR §83.18 A power-driven vessel underway shall keep out of the way of a sailing vessel (among others). 33 CFR §83.18 Rule 12 only comes into play once it is established that both vessels are, in fact, sailing vessels — and that Rules 9, 10, and 13 do not otherwise govern the situation. 33 CFR §83.18

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Why It Matters on the Exam

The OUPV and Master 100 GT written exams test Rule 12 in several recurring formats:

Direct rule-recall questions ask which vessel gives way in a described scenario. The answer almost always hinges on identifying which vessel is on port tack or which is to windward. Memorize the three scenarios in order: different tacks → port gives way; same tack → windward gives way; uncertainty → port gives way. 33 CFR §83.12

Vessel-status questions test whether a candidate recognizes that a vessel motoring with sails up is a power-driven vessel, not a sailing vessel. The definition at Rule 3 is unambiguous: propelling machinery must not be in use. 33 CFR §83.03 The daytime signal confirming that status is the inverted cone. 33 CFR §83.25

Lights questions frequently ask about the optional red-over-green masthead lights, the tricolor lantern, and the prohibition on using both simultaneously. 33 CFR §83.25 Know the size thresholds: 20 meters (tricolor option), 12 meters (cone not required), 7 meters (lights if practicable). 33 CFR §83.25

Hierarchy questions may present a sailing vessel meeting a vessel engaged in fishing and ask who gives way. Rule 18 controls: the sailing vessel gives way to the fishing vessel. 33 CFR §83.18 Rule 12 does not apply because both vessels are not sailing vessels.

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Common Pitfalls

Pitfall 1 — Confusing windward and leeward in Scenario 2. Candidates sometimes invert the rule and believe the leeward vessel must give way. The opposite is true: the windward vessel gives way to the leeward vessel when both are on the same tack. 33 CFR §83.12 Think of it this way: the windward vessel has more sea room to maneuver away; the leeward vessel is constrained by the wind shadow and the proximity of the other vessel.

Pitfall 2 — Applying Rule 12 when one vessel is motoring. If one vessel has its engine running, it is a power-driven vessel by definition, and Rule 18 — not Rule 12 — governs. 33 CFR §83.03 33 CFR §83.18 Rule 12 applies only when both vessels qualify as sailing vessels.

Pitfall 3 — Forgetting the cone for motorsailers. A vessel sailing under both sail and engine must display the inverted cone by day. 33 CFR §83.25 Exam questions sometimes describe a vessel with sails set and engine running and ask what shape is required. The answer is a cone, apex downward, exhibited forward where it can best be seen. Vessels under 12 meters are exempt from the requirement but may still display it. 33 CFR §83.25

Pitfall 4 — Combining the tricolor lantern with red-over-green masthead lights. The optional red-over-green all-round lights and the optional combined tricolor lantern serve similar purposes but are mutually exclusive. The Rule explicitly prohibits exhibiting them together. 33 CFR §83.25

Pitfall 5 — Misapplying Scenario 3. Scenario 3 applies only to a vessel that has the wind on the port side and sees a vessel to windward whose tack is uncertain. It does not apply to a starboard-tack vessel in the same situation. The starboard-tack vessel is already the stand-on vessel under Scenario 1 if the other is on port tack, and under Scenario 2 if both are on the same tack. 33 CFR §83.12

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Quick Check

Q1 — Vessel A has the wind on her port side. Vessel B has the wind on her starboard side. They are approaching with risk of collision. Which vessel keeps out of the way?

Vessel A keeps out of the way. Each vessel has the wind on a different side; the vessel with the wind on the port side gives way. 33 CFR §83.12

Q2 — Two sailing vessels are on starboard tack. Vessel A is to windward of Vessel B. Which vessel is the give-way vessel?

Vessel A (the windward vessel) keeps out of the way of Vessel B (the leeward vessel). When both vessels have the wind on the same side, the windward vessel gives way. 33 CFR §83.12

Q3 — A 15-meter vessel is proceeding under sail with her engine also running. What daytime shape is required, and where must it be displayed?

A conical shape, apex downward, exhibited forward where it can best be seen. Because the vessel is 15 meters — over 12 meters — the shape is required, not optional. 33 CFR §83.25

Q4 — A sailing vessel of 18 meters wishes to display the optional red-over-green all-round masthead lights. May she also use a combined tricolor lantern at the masthead?

No. The Rules explicitly prohibit exhibiting the red-over-green all-round lights in conjunction with the combined tricolor lantern. 33 CFR §83.25

Q5 — A sailing vessel underway meets a vessel engaged in fishing. Which vessel is the give-way vessel, and which Rule governs?

The sailing vessel is the give-way vessel. Rule 18 governs the responsibilities between different classes of vessels. A sailing vessel underway shall keep out of the way of a vessel engaged in fishing. Rule 12 does not apply because both vessels are not sailing vessels. 33 CFR §83.18

Q6 — A vessel on port tack sees a vessel to windward but cannot determine whether that vessel is on port or starboard tack. What action is required?

The port-tack vessel shall keep out of the way of the other vessel. When a vessel with the wind on the port side cannot determine with certainty the other vessel's tack, she gives way. 33 CFR §83.12

Q7 — How is "windward side" defined for purposes of Rule 12?

The windward side is the side opposite to that on which the mainsail is carried. For a square-rigged vessel, it is the side opposite to that on which the largest fore-and-aft sail is carried. 33 CFR §83.12